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2022 Vol. 21 No. 3 Previous Issue    Next Issue

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Review
Crop Science
Horticulture
Plant Protection
Animal Science · Veterinary Medicine
Agro-ecosystem & Environment
Food Science
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Ponkan (Citrus reticulata Blanco) is one of the most widely grown citrus species in China due to its elite palatability, strong flavor and good storability. The size and quality of Ponkan fresh fruit are two crucial factors determining its marketing and consumer preference. Various approaches have been employed to improve the fruit size and quality, including manual fruit thinning. Manual fruit thinning was found to increase the proportion of fruit with larger size and elevate the total soluble solids, leading to substantially improved fruit quality. Meanwhile, the fruits from the thinned trees exhibited higher mRNA abundance of sugar transporters, auxin and gibberellin biosynthesis or signaling genes. Therefore, manual fruit thinning could greatly improve fruit quality by promoting fruit expansion due to the increased auxin levels and expediting sugar accumulation through the up-regulation of sugar transporter genes. The cover photo shows the Ponkan fruits with favorable external appearance and internal fruit quality, which was provided by Prof. Liu Jihong from Huazhong Agricultural University, China. See pages 725–735 for more details.


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Review

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Cotton cultivation technology with Chinese characteristics has driven the 70-year development of cotton production in China FENG Lu, CHI Bao-jie, DONG He-zhong 2022, 21(3): 597-609.  DOI: 10.1016/S2095-3119(20)63457-8 Abstract ( )   PDF in ScienceDirect   Since the founding of the People’s Republic of China in 1949, significant achievements have been made in cotton production in China.  China has maintained its position as the world’s largest cotton producer for 33 years (1983–2015), with average annual increases of 3.5 and 3.9% in the unit yield and total output of cotton, respectively.  Cotton production has played an extremely important role in the development of the national economy and the improvement of living standards.  Although the cotton planting area has been reduced in recent years, the total output has remained relatively unchanged due to the continuous increase in the unit yield.  China’s dominant position in global cotton production is undoubtedly attributed to the progress and development of cotton cultivation technology.  Over the past 70 years, China has established a high-yielding and high-efficiency cotton cultivation mode that corresponds to its national conditions, including a large population and a limited land area.  Furthermore, cotton cultivation technology is constantly being innovated and developed to keep pace with the times.  In this paper, we review the development of cotton production and cultivation in China over the past 70 years, with a particular focus on the innovation and development of cotton cultivation technology with Chinese characteristics.  This review is intended to provide guidance for the sustainable development of China’s cotton production in the future and to provide a reference for global cotton production.

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Recent advances in plant immunity with cell death: A review YIN Jun-jie, XIONG Jun, XU Li-ting, CHEN Xue-wei, LI Wei-tao 2022, 21(3): 610-620.  DOI: 10.1016/S2095-3119(21)63728-0 Abstract ( )   PDF in ScienceDirect   Cell death is an important physiological phenomenon in life.  It can be programmed or unprogrammed.  Unprogrammed cell death is usually induced by abiotic or biotic stress.  Recent studies have shown that many proteins regulate both cell death and immunity in plants.  Here, we provide a review on the advances in plant immunity with cell death, especially the molecular regulation and underlying mechanisms of those proteins involved in both cell death and plant immunity.  In addition, we discuss potential approaches toward improving plant immunity without compromising plant growth.

Crop Science

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A locus TUTOU2, determines the panicle apical abortion phenotype of rice (Oryza sativa L.) in tutou2 mutant ZHU Zi-chao, LUO Sheng, LEI Bin, LI Xian-yong, CHENG Zhi-jun 2022, 21(3): 621-630.  DOI: 10.1016/S2095-3119(20)63447-5 Abstract ( )   PDF in ScienceDirect   Rice panicle apical abortion (PAA) is a detrimental agronomic trait resulting in spikelet number reduction and yield loss.  To understand its underlying molecular mechanism, we identified one recessive PAA mutant tutou2 from the offspring of tissue cultures.  The mutation locus was finely mapped to a 75-kb interval on the long arm of chromosome 10.  Sequence analysis revealed a single nucleotide substitution of A to T at the 941 position of LOC_Os10g31910 in tutou2, resulting in an amino acid change from isoleucine to phenylalanine.  Complementation analysis showed that the degenerated panicle phenotype in tutou2 was rescued in the transgenic lines.  A phenotype similar to tutou2 can also be obtained by LOC_Os10g31910 knockout in wild-type rice.  These results suggested that LOC_Os10g31910 is the causative locus TUTOU2 responsible for the tutou2 PAA phenotype and probably also the locus of DEL1, previously documented as a leaf senescence gene.  The significant phenotypic differences between del1 and tutou2 suggest that the locus DEL1/TUTOU2 plays roles in both leaf and panicle development which were not considered fully in previous studies.

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The removal of nitrate reductase phosphorylation enhances tolerance to ammonium nitrogen deficiency in rice HAN Rui-cai, XU Zhi-rong, LI Chen-yan, Adnan Rasheed, PAN Xiao-hua, SHI Qing-hua, WU Zi-ming 2022, 21(3): 631-643.  DOI: 10.1016/S2095-3119(20)63473-6 Abstract ( )   PDF in ScienceDirect   Nitrate reductase (NR) is a key enzyme for nitrogen assimilation in plants, and its activity is regulated by posttranslational phosphorylation.  To investigate the effects of dephosphorylation of the NIA1 protein on the growth and the physiological and biochemical characteristics of rice under different forms of nitrogen supplies, the phenotypes, nitrogen metabolism and reactive oxygen metabolism were measured in NIA1 phosphorylation site-directed mutant lines (S532D and S532A), an OsNia1 over-expression line (OE) and Kitaake (wild type, WT).  Compared with WT and OE, S532D and S532A have stronger nitrogen assimilation capacities.  When ammonium nitrate served as the nitrogen source, the plant heights, dry weights of shoots and chlorophyll (Chl) contents of S532D and S532A were lower than those of the WT and OE, whereas hydrogen peroxide (H2O2), malondialdehyde (MDA) and nitrite contents were higher.  When potassium nitrate served as the nitrogen source, the plant heights, dry weights of shoots and Chl contents of S532D and S532A were higher than those of the WT and OE, there were no significant differences in the contents of H2O2 and MDA in the leaves of the test materials, and the difference in nitrite contents among different lines decreased.  When ammonium sulfate served as the nitrogen source, there were no significant differences in the physiological indexes of the test materials, except NR activity.  Compared with ammonium nitrate and ammonium sulfate, the content of NH4+-N in the leaves of each plant was lower when potassium nitrate was used as the nitrogen source.  The qPCR results showed that OsGS and OsNGS1 were negatively regulated by downstream metabolites, and OsNrt2.2 was induced by nitrate.  In summary, when ammonium nitrate served as the nitrogen source, the weak growth of NIA1 phosphorylation site-directed mutant lines was due to the toxicity caused by the excessive accumulation of nitrite.  When potassium nitrate served as the nitrogen source, the assimilation rates of nitrate, nitrite and ammonium salt were accelerated in NIA1 phosphorylation site-directed mutant lines, which could provide more nitrogen nutrition and improve the tolerance of rice to ammonium nitrogen deficiency.  These results could provide a possible method to improve the efficiency of nitrogen utilization in rice under low-nitrogen conditions.

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Fine mapping and genetic analysis of resistance genes, Rsc18, against soybean mosaic virus LIU Sang-lin, CHENG Yan-bo, MA Qi-bin, LI Mu JIANG Ze, XIA Qiu-ju, NIAN Hai 2022, 21(3): 644-653.  DOI: 10.1016/S2095-3119(20)63569-9 Abstract ( )   PDF in ScienceDirect   Soybean mosaic virus (SMV) affects seed quality and production of soybean (Glycine max (L.) Merr.) worldwide.  SC18 is one of the dominant SMV strains in South China, and accession Zhonghuang 24 displayed resistance to SC18.  The F1, F2 and 168 F11 recombinant inbred lines (RILs) population derived from a hybridization between Zhonghuang 24 (resistant, R) and Huaxia 3 (susceptible, S) were used in this study.  According to the segregation ratios of the F2 generation (3R:1S) and the recombinant inbred lines (RILs) population (1R:1S), one dominant locus may regulate the resistance to SC18 in Zhonghuang 24.  By using composite interval mapping (CIM), Rsc18 was mapped to a 415.357-kb region on chromosome 13.  Three candidate genes, including one NBS-LRR type gene and two serine/threonine protein type genes, were identified according to the genetic annotations, which may be related to the resistance to SC18.  The qRT-PCR demonstrated that these genes were up-regulated in the R genotype compared to the control.  In conclusion, the findings of this research enhanced the understanding about the R genes at the Rsc18 locus.  Moreover, our results will provide insights for designing molecular markers to improve marker-assisted selection and developing new varieties with resistance to SC18.

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Improvement in winter wheat productivity through regulating PSII photochemistry, photosynthesis and chlorophyll fluorescence under deficit irrigation conditions Shahzad AlI, XU Yue-yue, MA Xiang-cheng, JIA Qian-min, JIA Zhi-kuan 2022, 21(3): 654-665.  DOI: 10.1016/S2095-3119(20)63409-8 Abstract ( )   PDF in ScienceDirect   This article has been retracted: please see Elsevier Policy on Article Withdrawal (http://www.elsevier.com/locate/withdrawalpolicy). This article has been retracted at the request of the Editor and Authors. The article was submitted by the first author Shahzad ALI without permission from corresponding author, Dr. JIA Zhi-kuan. The editor and corresponding author requested to retract the article. Apologies are offered to the readers of the journal.

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Systemic regulation of photosynthetic function in maize plants at graining stage under vertically heterogeneous light environment WU Han-yu, QIAO Mei-yu, ZHANG Wang-feng, WANG Ke-ru, LI Shao-kun, JIANG Chuang-dao 2022, 21(3): 666-676.  DOI: 10.1016/S2095-3119(20)63440-2 Abstract ( )   PDF in ScienceDirect   To cope with a highly heterogeneous light environment, photosynthesis in plants can be regulated systemically.  Currently, the majority of studies are carried out with various plants during the vegetative growth period.  As the reproductive sink improves photosynthesis, we wondered how photosynthesis is systemically regulated at the reproductive stage under a vertically heterogeneous light environment in the field.  Therefore, changes of light intensity within canopy, chlorophyll content, gas exchange, and chlorophyll a fluorescence transient were carefully investigated at the graining stage of maize under various planting densities.  In this study, a high planting density of maize drastically reduced the light intensities in the lower canopy, and increased the difference in vertical light distribution within the canopy.  With the increase of vertical heterogeneity, chlorophyll content, light-saturated photosynthetic rate and the quantum yield of electron transport in the ear leaf (EL) and the fourth leaf below the ear (FLBE) were decreased gradually, and the ranges of declines in these parameters were larger at FLBE than those at EL.  Leaves in the lower canopy were shaded artificially to further test these results.  Partial shading (PS) resulted in a vertically heterogeneous light environment and enhanced the differences in photosynthetic characteristics between EL and FLBE.  Removing the tassel and top leaves (RTL) not only improved the vertical light distribution within the canopy, but also reduced the differences in photosynthetic characteristics between the two leaves.  Taken together, these results demonstrated that maize plants could enhance the vertical heterogeneity of their photosynthetic function to adapt to their light environment; slight changes of the photosynthetic function in EL at the graining stage under a vertically heterogeneous light environment indicated that the systemic regulation of photosynthesis is weak at the graining stage.

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Factors influencing seed reserve utilization during seedling establishment in maize inbred lines LI Min, WEN Da-xing, SUN Qing-qing, WU Cheng-lai, LI Yan, ZHANG Chun-qing 2022, 21(3): 677-684.  DOI: 10.1016/S2095-3119(21)63608-0 Abstract ( )   PDF in ScienceDirect   Strong seedlings are essential for high yield.  To explore the foundation of strong seedlings, we investigated various factors influencing the conversion and distribution of seed storage reserves during seedling establishment in maize inbred lines.  Three maize inbred lines were used to explore the effects of seed size, seed vigor, illumination duration, temperature, water content, and salt concentration of the seedling medium on the utilization of seed storage reserves during seedling establishment.  The results showed that the conversion rate of small seeds was 3.69 to 17.71% higher than that of large seeds.  Moreover, prolonged illumination time was conducive to the formation of strong seedlings.  However, low temperature, drought stress and salt stress reduced the conversion rate of seed storage reserves and increased the root/shoot ratio.  These results could be used to guide field management during seedling emergence and develop improved germplasm with a high conversion rate of seed storage reserves.

Horticulture

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Nodulin 26-like intrinsic protein CsNIP2;2 is a silicon influx transporter in Cucumis sativus L. DUAN Yao-ke, SU Yan HAN Rong, SUN Hao, GONG Hai-jun 2022, 21(3): 685-696.  DOI: 10.1016/S2095-3119(21)63748-6 Abstract ( )   PDF in ScienceDirect   Nodulin 26-like intrinsic proteins (NIPs) are a family of channel-forming transmembrane proteins that function in the transport of water and other small molecules.  Some NIPs can mediate silicon transport across plasma membranes and lead to silicon accumulation in plants, which is beneficial for the growth and development of plants.  Cucumber is one of the most widely consumed vegetables; however, the functions of NIPs in this crop are still largely unknown.  Here, we report the functional characteristics of CsNIP2;2.  It was found that CsNIP2;2 is a tandem repeat of CsNIP2;1, which had been demonstrated to be a silicon influx transporter gene.  CsNIP2;2 has a selectivity filter composed of cysteine, serine, glycine and arginine (CSGR), which is different from all previously characterized silicon influx transporters in higher plants at the second helix position.  Xenopus laevis oocytes injected with CsNIP2;2 cRNA demonstrated a higher uptake of silicon than the control, and the uptake remained unchanged under low temperature.  CsNIP2;2 was found to be expressed in the root, stem, lamina and petiole, and exogenous silicon treatment decreased its expression in the stem but not in other tissues.  Transient expression of CsNIP2;2-eGFP fusion sequence in onion epidermal cells showed that CsNIP2;2 was localized to the cell nucleus, plasma membrane and an unknown structure inside the cell.  The results suggest that CsNIP2;2 is a silicon influx transporter in cucumber, and its subcellular localization and the selectivity filter are different from those of the previously characterized silicon influx transporters in other plants.  These findings may be helpful for understanding the functions of NIPs in cucumber plants.

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Tomato SlPti5 plays a regulative role in the plant immune response against Botrytis cinerea through modulation of ROS system and hormone pathways TANG Qiong, ZHENG Xiao-dong, GUO Jun, YU Ting 2022, 21(3): 697-709.  DOI: 10.1016/S2095-3119(21)63630-4 Abstract ( )   PDF in ScienceDirect   While SlPti5 has been shown to play a crucial role in the regulation of antagonistic genes in Solanum lycopersicum and Arabidopsis against pathogen infection, there have been no comprehensive studies on the effects of SlPti5 on the regulatory response mechanism of reactive oxygen species (ROS) system and hormone pathways during growth and disease resistance of tomato plants.  Here, we investigated the function of SlPti5 in the defense response of tomato against Botrytis cinerea utilizing a virus-induced gene silencing (VIGS)-based system.  Expression profile analysis showed that SlPti5 was significantly induced upon B. cinerea infection, with high expression levels in the leaves and fruit of tomato.  VIGS-based silencing of SlPti5 inhibited early vegetative growth, increased the plant’s susceptibility to infection, promoted the development of ROS, affected the expression of genes involved in the ROS scavenging system, and attenuated the expression of genes associated with pathogenesis and the ethylene/jasmonic acid signaling pathways.  In sum, our data demonstrated that SlPti5 stimulates the immune response of tomato plant to Botrytis cinerea infection by involving the ethylene (ET)- and jasmonic acid (JA)-mediated pathways and modulating the expression of some key pathogenesis-related (PR) genes.

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Tissue distribution and changes in dopamine during development and stress responses in Malus germplasm ZHANG Zhi-jun, ZHANG Jing, TANG Zhong-wen, WANG Yan-peng, GAO Teng-teng, LIU Xiao-min, MA Feng-wang, LI Chao 2022, 21(3): 710-724.  DOI: 10.1016/S2095-3119(20)63590-0 Abstract ( )   PDF in ScienceDirect   Dopamine is a catecholamine and an anti-oxidant which functions in responses to stress and it interacts with plant hormones to mediate plant development.  At present, there are few studies on the functions of dopamine in apple.  This study developed a method for dopamine determination which was used to analyze dopamine in Malus germplasm, in order to clarify the tissue distribution, developmental changes, diurnal variations, and stress responses in apple trees.  First, the proposed method was verified.  The linear range of quantification was robust from 0.1 to 20 ng mL–1.  The instrumental, inter-day precision, and sample repeatability relative standard deviations were 1.024, 5.607, and 7.237%, respectively.  The spiked recovery was greater than 100%, indicating the feasibility of the method and its suitability for the rapid analysis of dopamine in Malus.  Next, the dopamine content was measured in 322 Malus tissues.  The results showed that the dopamine level in Malus was low and the average dopamine content in leaf was higher than in peel and flesh.  The dopamine had a skewed distribution that deviated to the right in cultivars and wild accessions.  Finally, the tissue specificity, developmental changes, diurnal changes, and responses to stress were analyzed.  In cultivar ‘Pinova’ (Malus domestica), the dopamine concentration was the highest in leaf buds and lowest in flesh.  The dopamine contents in leaf and flesh decreased with the growth and development of cultivar ‘Liangxiang’ (Malus domestica).  The dopamine content of apple leaves was higher after either drought or salinity stress as compared to the control.  In this study, a dopamine detection method for apple was established based on HPLC-MS and shown to be a robust approach.  This study provides a framework for future research on elucidating the tissue distribution, developmental changes, diurnal variation, and stress responses of dopamine in apple trees.

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Manual thinning increases fruit size and sugar content of Citrus reticulata Blanco and affects hormone synthesis and sugar transporter activity LIU Cong, LI De-xiong, HUANG Xian-biao, Zhang Fu-qiong, Xie Zong-zhou, Zhang Hong-yan, Liu Ji-hong 2022, 21(3): 725-735.  DOI: 10.1016/S2095-3119(20)63502-X Abstract ( )   PDF in ScienceDirect   Manual fruit thinning (MFT) in fruit trees has been previously shown to increase fruit size and enhance fruit quality, but the effect of MFT on Ponkan (Citrus reticulata Blanco) and the underlying mechanisms remain poorly understood.  In this study, efforts were made to elucidate how MFT influences the fruit quality of Ponkan.  The results showed that MFT substantially increased fruit size and elevated fruit total soluble solids in comparison with the fruit from the unthinned trees (used as control).  Expression analyses demonstrated that mRNA abundance of three important sugar transporter genes, including CrSUT1, CrSTP1 and CrTMT1, was evidently elevated in the flesh of thinned fruit when compared with those of the control.  In addition, MFT prominently up-regulated the transcript levels of various auxin and gibberellin (GA) biosynthesis and signaling genes, including CrYUC6, CrAUX/IAA, CrGA20ox1 and CrGA3ox1.  Concurrently, the contents of endogenous IAA and GA3, measured at 90 d after fruit thinning, were notably elevated in the fruit from trees with the thinning treatment relative to the control, although no difference was detected in the two groups before the thinning manipulation.  Taken together, these results indicate that manual fruit thinning could greatly improve fruit quality, which may be attributed to promoting fruit expansion due to the increased auxin levels and expediting sugar accumulation through the up-regulation of sugar transporter genes.

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The comparative analysis and identification of secondary metabolites between Tibet wild and cultivated pomegranates (Punica granatum L.) in China GUO Lin-hui, GE Da-peng, REN Yuan, DONG Jian-mei, ZHAO Xue-qing, LIU Xue-qing, YUAN Zhao-he 2022, 21(3): 736-750.  DOI: 10.1016/S2095-3119(21)63642-0 Abstract ( )   PDF in ScienceDirect   Secondary metabolites are closely related to the nutritional quality and health functions of plants.  We investigated the secondary metabolites of both wild (n=23) and cultivated (n=27) pomegranate plants (Punica granatum L.) growing in China.  The total flavonoid (TF) and tannin (TT) contents from the peel and juice were determined and the secondary metabolites in the peel (ZLP) and juice (ZLZ) of ‘Zela 4’ were identified using liquid chromatography–electrospray ionization tandem mass spectrometry (LC–ESI-MS/MS).  Analysis of variance (P<0.05) showed that there were significant differences in the TF content of peel (TF (P)) and juice (TF (J)), and the TT content of peel (TT (P)) and juice (TT (J)) among different pomegranate accessions.  Pearson correlation analysis showed that latitude and altitude might be the main environmental factors affecting TF and TT contents in pomegranates.  In this study, 279 secondary metabolites were identified in the ZLP and ZLZ.  In addition, we report for the first time 227 secondary metabolites in pomegranates.  Using orthogonal partial least squares discriminant analysis, 90 differential metabolites were identified in ZLP and ZLZ.  In addition, we screened eight specific germplasms (high-TF (P), ‘Junyong 3’; low-TF (P), ‘Yanzhihong’; high-TF(J), ‘Zela 4’; low-TF (J), ‘Yudazi’, high-TT (P), ‘Junyong 4’; low-TT (P), ‘Anba 1’; high-TT(J), ‘Yeba 1’; and low-TT (J), ‘Baihuayushizi’).  The results of our study provide a reference for the development and utilization of wild pomegranate resources and pomegranate breeding in China.

Plant Protection

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PnSCR82, a small cysteine-rich secretory protein of Phytophthora nicotianae, can enhance defense responses in plants WANG Ya-di, LI Fei, ZHANG Xin, LIU Ting-li, LIANG Wen-xing, LI De-long 2022, 21(3): 751-761.  DOI: 10.1016/S2095-3119(21)63681-X Abstract ( )   PDF in ScienceDirect   A number of plant pathogenic species of Phytophthora are known to produce different classes of secretory proteins during interactions with their hosts.  Although several small cysteine-rich (SCR) secretory proteins, conserved in oomycete pathogens, have been identified in Phytophthora, their specific involvement in these interactions remains unknown.  In this study, an SCR effector encoded by Pnscr82 in P. nicotianae was identified and shown to have similarities to P. cactorum phytotoxic protein, PcF (Phytophthora cactorum Fragaria).  Agroinfection with potato virus X vector, PnSCR82, was capable of inducing plant hypersensitive cell death in Nicotiana benthamiana and Solanum lycopersicum.  Real-time PCR results indicated that transiently expressed PnSCR82 in N. benthamiana leaves activated the jasmonate, salicylic acid and ethylene signaling pathways.  Transient expression of PnSCR82 enhanced plant resisitance to P. capsici.  In summary, our results demonstrated that P. nicotianae PnSCR82 elicits defensive responses in N. benthamiana and may potentially play a significant role in future crop protection programs.

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Melanin, DNA replication, and autophagy affect appressorium development in Setosphaeria turcica by regulating glycerol accumulation and metabolism GUO Xiao-yue, LIU Ning, LIU Bing-hui, ZHOU Li-hong, CAO Zhi-yan, HAN Jian-min, DONG Jin-gao 2022, 21(3): 762-773.  DOI: 10.1016/S2095-3119(21)63679-1 Abstract ( )   PDF in ScienceDirect   Setosphaeria turcica (syn. Exserohilum turcicum) is the pathogenic fungus of maize (Zea mays) that causes northern leaf blight, which is a major maize disease worldwide.  Melanized appressoria are highly specialized infection structures formed by germinated conidia of S. turcica that infect maize leaves.  The appressorium penetrates the plant cuticle by generating turgor, and glycerol is known to be the main source of the turgor.  Here, the infection position penetrated by the appressorium on maize leaves was investigated, most of the germinated conidia entered the leaf interior by directly penetrating the epidermal cells, and the appressorium structure was necessary for the infection, whether it occurred through epidermal cells or stomata.  Then, to investigate the effects of key factors in the development of the appressorium, we studied the effects of three inhibitors, including a melanin inhibitor (tricyclazole, TCZ), a DNA replication inhibitor (hydroxyurea, HU), and an autophagy inhibitor (3-methyladenine, 3-MA), on appressorium turgor and glycerol content.  As results, appressorium turgor pressure and glycerol concentration in the appressorium reached their highest levels at the mature stage of the appressorium under the control and inhibitor treatments.  The three inhibitors had the greatest effects on appressorium turgor pressure at this stage.  Glycogen and liposomes are the main substances producing glycerol.  It was also found inhibitors affected the distribution of glycogen and liposomes, which were detected in the conidia, the germ tube, and the appressorium during appressorium development.  This study provides profound insight into the relationship between appressorium turgor pressure and glycerol content, which was affected by the synthesis of melanin, DNA replication, and autophagy in the developing appressorium during a S. turcica infection.

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Incidence and prevalence levels of three aphid-transmitted viruses in crucifer crops in China ZHANG Xiao-yan, PENG Yan-mei, XIANG Hai-ying, WANG Ying, LI Da-wei, YU Jia-lin, HAN Cheng-gui 2022, 21(3): 774-780.  DOI: 10.1016/S2095-3119(21)63618-3 Abstract ( )   PDF in ScienceDirect   Poleroviruses, which are distributed worldwide, infect many crops of economic importance and cause severe plant diseases.  Brassica yellows virus (BrYV), which has three genotypes, A, B, and C, is a newly identified polerovirus infecting crucifer crops in China, but its distribution is still unclear.  Here, we report the distribution and prevalence levels of the three BrYV genotypes in crucifer crops in China.  A total of 570 crucifer leaf samples randomly collected from 22 provinces, four ethnic minority autonomous regions, and three municipalities in China were tested for BrYV.  RT-PCR detection showed that 97 of the field samples were positive for BrYV, and the average incidence of BrYV was 17.0%.  The virus was detected in 22 provinces, with high incidences in north, northwest, and northeast China.  The multiplex RT-PCR amplification of the three BrYV genotypes revealed that both single and mixed infections occurred.  Among the BrYV infections, 38.1% were mix-infected by more than two viral genotypes, and 8.2% samples were mix-infected by three viral genotypes.  Our findings indicated a widespread prevalence of BrYV in China, and BrYV mixed infections with Turnip mosaic virus and Cucumber mosaic virus in crucifer crops are common.  This study is the first large-scale survey of BrYV in crucifer crops in China.  The information generated in this investigation will contribute to the national prevention and control of viral diseases.

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Molecular and in vitro biochemical assessment of chemosensory protein 10 from the brown planthopper Nilaparvata lugens at acidic pH Muhammad Irfan WARIS, Aneela YOUNAS, Rana Muhammad Kaleem ULLAH, Fatima RASOOL, Muhammad Muzammal ADEEL, WANG Man-qun 2022, 21(3): 781-796.  DOI: 10.1016/S2095-3119(20)63494-3 Abstract ( )   PDF in ScienceDirect   Chemosensory proteins (CSPs) are important molecular components of the insect olfactory system, which are involved in capturing, binding, and transporting hydrophobic odour molecules across the sensillum in sensillar lymph in regulating insect behavior.  This protein family (CSPs) is also involved in many other systems that are not linked to olfactory receptors in olfactory sensilla.  The brown planthopper (BPH) is a monophagous pest of rice that causes damage by sucking phloem sap and transmitting a number of diseases caused by viruses.  In this study, fluorescence competitive binding assay and fluorescence quenching assay at acidic pH were performed as well as homology modelling to describe the binding affinity of NlugCSP10.  Fluorescence competitive binding assay (FCBA) demonstrated that NlugCSP10 bound strongly to nonadecane, farnesene, and 2-tridecanone at acidic pH.  The results of FCBA indicated that NlugCSP10 bound different ligands at the physiological pH (5.0) of the bulk sensillum lymph.  Fluorescence quenching assay demonstrated that NlugCSP10 generated a stable complex with 2-tridecanone, while two ligands nonadecane and farnesene collided due to molecular collisions.  The interaction of selected ligands with the modelled structure of NlugCSP10 was also analyzed, which found the key amino acids (Gln23, Gln24, Gln25, Asn27, Met33, Ser34, Ile35, Tyr36, Asn42, Met43, Val45, Asn46, Asn93, Arg96, Ala97, Lys99, and Ala100) in NlugCSP10 that were involved in binding of volatile compounds.  The present study contributes to the binding profile of NlugCSP10 that promotes the development of behaviorally active ligands based on BPH olfactory system.

Animal Science · Veterinary Medicine

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Quantification and prediction of enteric methane emissions from Chinese lactating Holstein dairy cows fed diets with different dietary neutral detergent fiber/non-fibrous carbohydrate (NDF/NFC) ratios DONG Li-feng, JIA Peng, LI Bin-chang, WANG Bei, YANG Chun-lei, LIU Zhi-hao, DIAO Qi-yu 2022, 21(3): 797-811.  DOI: 10.1016/S2095-3119(21)63825-X Abstract ( )   PDF in ScienceDirect   Methane (CH4) emissions from ruminant production are a significant source of anthropogenic greenhouse gas production, but few studies have examined the enteric CH4 emissions of lactating dairy cows under different feeding regimes in China.  This study aimed to investigate the influence of different dietary neutral detergent fiber/non-fibrous carbohydrate (NDF/NFC) ratios on production performance, nutrient digestibility, and CH4 emissions for Holstein dairy cows at various stages of lactation. It evaluated the performance of CH4 prediction equations developed using local dietary and milk production variables compared to previously published prediction equations developed in other production regimes.  For this purpose, 36 lactating cows were assigned to one of three treatments with differing dietary NDF/NFC ratios: low (NDF/NFC=1.19), medium (NDF/NFC=1.54), and high (NDF/NFC=1.68).  A modified acid-insoluble ash method was used to determine nutrient digestibility, while the sulfur hexafluoride technique was used to measure enteric CH4 emissions.  The results showed that the dry matter (DM) intake of cows at the early, middle, and late stages of lactation decreased significantly (P<0.01) from 20.9 to 15.4 kg d–1, 15.3 to 11.6 kg d–1, and 16.4 to 15.0 kg d–1, respectively, as dietary NDF/NFC ratios increased.  Across all three treatments, DM and gross energy (GE) digestibility values were the highest (P<0.05) for cows at the middle and late lactation stages.  Daily CH4 emissions increased linearly (P<0.05), from 325.2 to 391.9 kg d–1, 261.0 to 399.8 kg d–1, and 241.8 to 390.6 kg d–1, respectively, as dietary NDF/NFC ratios increased during the early, middle, and late stages of lactation.  CH4 emissions expressed per unit of metabolic body weight, DM intake, NDF intake, or fat-corrected milk yield increased with increasing dietary NDF/NFC ratios.  In addition, CH4 emissions expressed per unit of GE intake increased significantly (P<0.05), from 4.87 to 8.12%, 5.16 to 9.25%, and 5.06 to 8.17% respectively, as dietary NDF/NFC ratios increased during the early, middle, and late lactation stages.  The modelling results showed that the equation using DM intake as the single variable yielded a greater R2 than equations using other dietary or milk production variables.  When data obtained from each lactation stage were combined, DM intake remained a better predictor of CH4 emissions (R2=0.786, P=0.026) than any other variables tested.  Compared to the prediction equations developed herein, previously published equations had a greater root mean square prediction error, reflecting their inability to predict CH4 emissions for Chinese Holstein dairy cows accurately.  The quantification of CH4 production by lactating dairy cows under Chinese production systems and the development of associated prediction equations will help  establish regional or national CH4 inventories and improve mitigation approaches to dairy production.

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Detection of quantitative trait loci (QTL) associated with spring regrowth in alfalfa (Medicago sativa L.) JIANG Xue-qian, ZHANG Fan, WANG Zhen, LONG Rui-cai, LI Ming-na, HE Fei, YANG Xi-jiang, YANG Chang-fu, JIANG Xu, YANG Qing-chuan, WANG Quan-zhen, KANG Jun-mei 2022, 21(3): 812-818.  DOI: 10.1016/S2095-3119(21)63671-7 Abstract ( )   Spring regrowth is an important trait for perennial plants including alfalfa, the most cultivated forage legume worldwide.  However, the genetic and genomic basis of the trait is largely unknown in alfalfa due to its complex genetic background of the tetroploid genome.  The objective of this study was to identify quantitative trait loci (QTLs) associated with spring regrowth using high-resolution genetic linkage maps we constructed previously.  In total, 36 significant additive effect QTLs for the trait were detected.  Among them, 10 QTLs individually explained more than 10% of the phenotypic variation (PVE) with four in P1 and six in P2.  Six overlapped QTLs intervals were detected with two and four intervals distributed in P1 and P2, respectively.  In P1, both overlapped genomic regions were located on homolog 7D.  In P2, the four QTLs with PVE>10% were co-localized on homolog 6D.  Meanwhile, six pairs of significant epistatic QTLs were identified in P2.  Screening of potential candidate genes associated with four overlapped QTLs (qCP2019-8, qLF2019-5, qLF2020-4, and qBLUP-3) narrowed down one candidate annotated as MAIL1.  The Arabidopsis homolog gene has been reported to play an important role in plant growth.  Therefore, the detected QTLs are valuable resources for genetic improvement of alfalfa spring vigor using marker-assisted selection (MAS), and further identification of the associated genes would provide insights into genetic control of spring regrowth in alfalfa.

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Development of a recombinant pB602L-based indirect ELISA assay for detecting antibodies against African swine fever virus in pigs WANG Peng-fei, WANG Ming, SHI Zhi-bin, SUN Zhen-zhao, WEI Li-li, LIU Zai-si, WANG Shi-da, HE Xi-jun, WANG Jing-fei 2022, 21(3): 819-825.  DOI: 10.1016/S2095-3119(21)63767-X Abstract ( )   PDF in ScienceDirect   African swine fever (ASF), caused by the African swine fever virus (ASFV), is a devastating disease of domestic and wild pigs.  There is no effective vaccine, and the control of the disease relies mainly on surveillance and early detection of infected pigs.  Previously, serological assays, such as ELISA, have been developed mainly based on recombinant structural viral proteins of ASFV, including p72, p54, and p30.  However, the antibodies against these proteins do not provide efficient protection against ASFV infection in pigs.  Therefore, new serological assays that can be applied for clinical diagnosis and evaluating serological immune response in vaccinated pigs are still required.  In this study, we expressed and purified a recombinant pB602L protein.  The purified pB602L protein was then used as an antigen to develop an indirect ELISA assay.  This assay has no cross-reaction with the anti-sera against the 15 most common pig pathogens in China, such as classical swine fever virus, pseudorabies virus, and porcine parvovirus.  This assay and a commercial ELISA kit were then used to detect 60 field pig serum samples, including an unknown number of anti-ASFV sera.  The coincidence of the two assays was 95%.  Furthermore, the pB602L-based ELISA was employed to test the antibody responses to the seven-gene-deleted ASFV strain HLJ/18-7GD in pigs.  The results showed that the antibody levels in all vaccinated pigs, starting from the 10th day post-inoculation, have increased continuously during the observation period of 45 days.  Our results indicate that this pB602L-based indirect ELISA assay can be employed potentially in the field of ASFV diagnosis.

Agro-ecosystem & Environment

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Dynamics of organic carbon and nitrogen in deep soil profile and crop yields under long-term fertilization in wheat-maize cropping system Muhammad QASWAR, LI Dong-chu, HUANG Jing, HAN Tian-fu, Waqas AHMED, Sehrish ALI, Muhammad Numan KHAN, Zulqarnain Haider KHAN, XU Yong-mei, LI Qian, ZHANG Hui-min, WANG Bo-ren, Ahmad TAUQEER 2022, 21(3): 826-839.  DOI: 10.1016/S2095-3119(20)63501-8 Abstract ( )   PDF in ScienceDirect   Soil organic carbon (SOC) and nitrogen (N) are two of the most important indicators for agricultural productivity.  The primary objective of this study was to investigate the changes in SOC and N in the deep soil profile (up to 100 cm) and their relationships with crop productivity under the influence of long-term (since 1990) fertilization  in the wheat-maize cropping system.  Treatments included CK (control), NP (inorganic N and phosphorus (P) fertilizers), NPK (inorganic N, P and potassium fertilizers), NPKM (NPK plus manure), and M (manure).  Crop yield and the properties of topsoil were measured yearly from 2001 to 2009.  C and N contents were measured at five different depths in 2001 and 2009.  The results showed that wheat and maize yields decreased between 2001 and 2009 under the inorganic fertilizer (NP and NPK) treatments.  The average yield between 2001 and 2009 under the NP, NPK, NPKM, and M treatments (compared with the CK treatment) increased by 38, 115, 383, and 381%, respectively, for wheat and 348, 891, 2 738, and 1 845%, respectively, for maize.  Different long-term fertilization treatments significantly changed coarse free particulate (cfPOC), fine free particulate (ffPOC), intramicroaggregate particulate (iPOC), and mineral-associated (mSOC) organic carbon fractions.  In the experimental years of 2001 and 2009, soil fractions occurred in the following order for all treatments: mSOC>cfPOC>iPOC>ffPOC.  All fractions were higher under the manure application treatments than under the inorganic fertilization treatments.  Compared to the inorganic fertilization treatments, manure input enhanced the stocks of SOC and total N in the surface layer (0–20 cm) but decreased SOC and N in the deep soil layer (80–100 cm).  This reveals the efficiency of manure in increasing yield productivity and decreasing risk of vertical loss of nutrients, especially N, compared to inorganic fertilization treatments.  The findings provide opportunities for understanding deep soil C and N dynamics, which could help mitigate climate change impact on agricultural production and maintain soil health.

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Interactions between phosphorus availability and microbes in a wheat–maize double cropping system: a reduced fertilization scheme YU Xiao-jing, CHEN Qi, SHI Wen-cong, GAO Zheng, SUN Xiao, DONG Jing-jing, LI Juan, WANG Heng-tao, GAO Jian-guo, LIU Zhi-guang, ZHANG Min 2022, 21(3): 840-854.  DOI: 10.1016/S2095-3119(20)63599-7 Abstract ( )   PDF in ScienceDirect   Mechanisms controlling phosphorus (P) availability and the roles of microorganisms in the efficient utilization of soil P in the wheat–maize double cropping system are poorly understood.  In the present study, we conducted a pot experiment for four consecutive wheat–maize seasons (2016–2018) using calcareous soils with high (30.36 mg kg–1) and low (9.78 mg kg–1) initial Olsen-P content to evaluate the effects of conventional P fertilizer application to both wheat and maize (Pwm) along with a reduced P fertilizer application only to wheat (Pw).  The microbial community structure along with soil P availability parameters and crop yield were determined.  The results showed that the Pw treatment reduces the annual P input by 33.3% without affecting the total yield for at least two consecutive years as compared with the Pwm treatment in the high Olsen-P soil.  Soil water-soluble P concentrations in the Pw treatment were similar to those in the Pwm treatment at the 12-leaf collar stage when maize requires the most P.  Furthermore, the soil P content significantly affected soil microbial communities, especially fungal communities.  Meanwhile, the relative abundances of Proteobacteria and alkaline phosphatase (ALP) activity of Pw were significantly higher (by 11.4 and 13.3%) than those of Pwm in soil with high Olsen-P.  The microfloral contribution to yield was greater than that of soil P content in soil with high Olsen-P.  Relative abundances of Bacillus and Rhizobium were enriched in the Pw treatment compared with the Pwm treatment.  Bacillus showed a significant positive correlation with acid phosphatase (ACP) activity, and Rhizobium displayed significant positive correlations with ACP and ALP in soil with high Olsen-P, which may enhance P availability.  Our findings suggested that the application of P fertilization only to wheat is practical in high P soils to ensure optimal production in the wheat and maize double cropping system and that the soil P availability and microbial community may collaborate to maintain optimal yield in a wheat–maize double cropping system.

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The ciliate protozoan Colpoda cucullus can improve maize growth by transporting soil phosphates ZHANG Wen-li, LIN Qi-mei, Li Gui-tong, ZHAO Xiao-rong 2022, 21(3): 855-861.  DOI: 10.1016/S2095-3119(21)63628-6 Abstract ( )   PDF in ScienceDirect   Little is known regarding the ability of protozoans to transfer phosphates and improve maize growth.  The objective of this study was to determine whether Colpoda cucullus could improve the maize phosphorus (P) level by transferring phosphate.  In this three-compartment root box study, the soil in the outer compartment was inoculated with the common ciliate, C. cucullus, together with the addition of either KH232PO4, rock phosphate (RP), super phosphate (SP) or ammonium phosphate (AP), and then maize was grown in the inner compartment.  The results showed that the maize plants grown in the soil inoculated with C. cucullus had much higher 32P radioactivity than the control.  Colpoda cucullus inoculation resulted in significant increases in dry matter by up to 25.07%, and nitrogen (N), P and potassium (K) absorption by 1–36% (P<0.05).  Soil available P in the inner compartment of the root box was also enhanced by at least 30% due to the ciliate inoculation (P<0.05).  It was therefore suggested that phosphates might be transported from the outer to inner compartments by the inoculated C. cucullus and then absorbed by the maize plant.

Food Science

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Transcriptome and phytochemical analyses reveal roles of characteristic metabolites in the taste formation of white tea during withering process ZHOU Cheng-zhe, ZHU Chen, LI Xiao-zhen, CHEN Lan, XIE Si-yi, CHEN Guang-wu, ZHANG Huan, LAI Zhong-xiong, LIN Yu-ling, GUO Yu-qiong 2022, 21(3): 862-877.  DOI: 10.1016/S2095-3119(21)63785-1 Abstract ( )   PDF in ScienceDirect   In the postharvest processing of tea leaves, withering is the first indispensable manufacturing process which produces the mellow, umami and sweet taste of white tea.  In this study, we aimed to determine the dynamic changes of the main metabolites and clarify the key differentially expressed genes (DEGs) involved in forming the characteristic taste of white tea during withering.  Phytochemical analyses revealed that the contents of total catechins and starch decreased continuously, whereas the contents of theaflavin, γ-aminobutyric acid (GABA), maltose, and soluble sugars increased significantly during withering (from 0–48 h).  Meanwhile, the elevation of α-amylase (AMY), β-amylase (BAM), total amylase, and glutamate decarboxylase (GAD) activities may be correlated with the accumulation of GABA and maltose.  By transcriptome sequencing, we detected 9 707, 15 921, 17 353, and 17 538 DEGs at 12, 24, 36, and 48 h of the withering process, respectively, compared with 0 h sample (fresh leaves).  The transcript levels of most of the DEGs involved in catechin biosynthesis were significantly inhibited, whereas those involved in catechin oxidation were significantly up-regulated, which could be correlated to a decrease in catechin content and an increase in theaflavin content.  The DEGs involved in GABA biosynthesis were considerably up-regulated, and the down-regulation of SPMS could reduce the competition for converting spermidine to GABA.  The up-regulation of the AMY and BAM genes could trigger starch degradation, resulting in the increase of soluble sugar content.  These results provide new insights into the importance of the withering process to the characteristic taste of white tea.

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Protective effect of high-oleic acid peanut oil and extra-virgin olive oil in rats with diet-induced metabolic syndrome by regulating branched-chain amino acids metabolism ZHAO Zhi-hao, SHI Ai-min, GUO Rui, LIU Hong-zhi, HU Hui, WANG Qiang 2022, 21(3): 878-891.  DOI: 10.1016/S2095-3119(21)63851-0 Abstract ( )   PDF in ScienceDirect   High-oleic acid peanut oil (HOPO) and extra-virgin olive oil (EVOO) have been reported previously to have an attenuating effect on metabolic syndrome (MS).  This study aimed to evaluate the metabolic effect of HOPO and EVOO supplementation in attenuating MS and the role of gut microbiota in regulating the metabolic profile.  Sprague-Dawley rats were continuously fed with a normal diet, high-fructose and high-fat (HFHF) diet, HFHF diet containing HOPO, or a HFHF diet containing EVOO for 12 weeks.  The metabolomics profiles of feces and serum samples were compared using untargeted metabolomics based on UPLC-Q/TOF-MS.  Partial Least Squares Discriminant Analysis (PLS-DA) was used to identify the potential fecal and serum biomarkers from different groups.  Correlation between gut microbiota and biomarkers was assessed, and pathway analysis of serum biomarkers was conducted.  Differences in metabolic patterns in feces and serum were observed among different groups.  There were 8 and 12 potential biomarkers in feces and 15 and 6 potential biomarkers in serum of HOPO group and EVOO group, respectively, suggesting that HOPO and EVOO supplementation mainly altered amino acids, peptides, and their analogs in feces and serum.  The branched-chain amino acids (BCAAs) biosynthesis pathway was identified as a major pathway regulated by HOPO or EVOO.  This study suggests that HOPO and EVOO supplementation ameliorate diet-induced MS, mainly via modulation of the BCAAs biosynthesis pathway.

Letter

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Current station and suggestions for mechanical grain harvesting of corn in China XIE Rui-zhi, MING Bo, WANG Ke-ru, HOU Peng, LI Shao-kun 2022, 21(3): 892-897.  DOI: 10.1016/S2095-3119(21)63804-2 Abstract ( )   PDF in ScienceDirect

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First record of the golden potato nematode Globodera rostochiensis in Yunnan and Sichuan provinces of China JIANG Ru, PENG Huan, LI Yun-qing, LIU Hui, ZHAO Shou-qi, LONG Hai-bo, HU Xian-qi, GE Jian-jun, LI Xing-yue, LIU Miao-yan, SHAO Bao-lin, PENG De-liang 2022, 21(3): 898-899.  DOI: 10.1016/S2095-3119(21)63845-5 Abstract ( )   PDF in ScienceDirect   The potato cyst nematodes (PCN) Globodera rostochiensis (Wollenweber) Skarbilovich, 1959 is considered the most damaging nematode pest of potato worldwide that causes significant yield losses, and this nematode is recognized and listed as a quarantine nematode in many countries (EPPO 2017).  China is currently the largest producer of potato in the world, while the total production is also the highest (Guan and Cai 2019).  The survey for cyst nematodes on potato were conducted in Yunnan and Sichuan provinces of China during 2018–2020, numerous cysts were observed on potato roots in Huize County and Ludian County of Yunnan Province, Zhaojue County and Yuexi County of Sichuan Province.  Cysts and second-stage juveniles (J2s) were isolated from each soil sample using the Cobb decanting and sieving method.  The morphology of cysts and J2s and molecular analysis established the identity of this species as golden cyst nematode Globodera rostochiensis (Subbotin et al. 2010).  For morphological analysis, the cysts were characterized by smoothly rounded with a small projecting neck, brown and golden color, terminal cone was absent and circumfenestrate.  The key morphometrics of cysts (n=25) were: length excluding neck 705±24 (689–747) μm, width 698±28 (678–759) μm, number of cuticular ridges between anus and vulval fenestra 17.3±1.7 (14–19); fenestral diameter 13.6±1.1 (12.25–15.45) μm; distance from anus to the edge of fenestra 63.7±11.3 (48.23–79.14) μm; Granek’s ratio 4.7±0.7 (3.92–5.75).  The key morphometrics of J2s (n=25): body length 453.9±16.6 (440–496) μm, stylet length 21.9±1.0 (20.3–24.3) μm, tail length 51.1±3.2 (45.5–55.5) μm, and hyaline region length 24.4±2.5 (21.7–29.9) μm.  Morphology of the cysts and J2 were consistent with those of G. rostochiensis (Subbotin et al. 2010; EPPO 2017).  Moreover, the identification result was confirmed by PCR using universal primers TW81 (5´-GTTTCCGTAGGTGAACCTGC-3´) and AB28 (5´-ATATGCTTAAGTTCAGCGGGT-3´) for ITS region and D2A (5´-TTTTTTGGGCATCCTGAGGTTTAT-3´) D3B (5´-AGCACCTAAACTTAAAACATAATGAAAATG-3´) for rDNA-28S region, respectively.  The ITS rDNA sequences (GenBank accessions MZ042365, MZ042366, MZ042369, and MZ042370) exhibited 99.83% identity match to G. rostochiensis sequences available in the GenBank (GQ294513).  Sequence from the 28S region (GenBank accessions MZ057595, MZ057596, MZ057599, and MZ057600) was 99.33% similar to those of G. rostochiensis isolate from MF773722.  The species was also confirmed with species-specific primers ITS5 (5´-GGAAGTAAAAGTCGTAACAAGG-3´) and PITSr3 (5´-AGCGCAGACATGCCGCAA-3´) (Bulman and Marshall 1997), a single 434-bp fragment was obtained from Huize, Ludian, Zhaojue and Yuexi populations.  The pathog enicity testing of Huize, Ludian, Zhaojue and Yuexi, three weeks-old potato plants (cv. Qinshu 9) were inoculated with 2 000 eggs, and cultured in an incubator at 23°C/20°C with a 16 h/8 h light/dark photoperiod.  After three months inoculation, 36±7.2 cysts and females were extracted from the infested potato roots, no females and cysts were observed on control plants.   This is the first report of potato golden cyst nematode G. rostochiensis in China.