2022 Vol. 21 No. 8 Previous Issue    Next Issue

    Crop Science
    Plant Protection
    Animal Science · Veterinary Medicine
    Agro-ecosystem & Environment
    Food Science
    Short Communication

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    Historical trends in maize morphology from the 1950s to the 2010s in China
    MA Da-ling, XIE Rui-zhi, YU Xiao-fang, LI Shao-kun, GAO Ju-lin
    2022, 21(8): 2159-2167.  DOI: 10.1016/S2095-3119(21)63697-3
    Abstract ( )   PDF in ScienceDirect  
    The morphology of the plant and ear is a preliminary selection characteristic in breeding new varieties of maize.  As new maize cultivars were developed from the 1950s through the 2010s in China, most had changes in both plant and ear morphological characteristics that contributed substantially to maize yield gains.  Over the seven decades, plant and ear height fluctuated with a small increase from the 1950s to 2000s, and then a decrease in the 2010s, while the ear ratio and internodes length below the ear decreased significantly.  Leaf angles became significantly more upright, especially for the leaves above the ear, and the leaf area per plant improved markedly.  Leaf orientation increased from the 1950s to the 2000s then decreased in the 2010s.  Tassel size and the anthesis–silking interval were both reduced substantially.  Ear diameter, kernel number, and kernel weight increased from the 1950 to the 2000s, then decreased in the 2010s under the same cultivation conditions.  We found that modern maize hybrids have a lower plant height, ear height and ear ratio which increased lodging resistance, a more erect leaf which increased high-density planting tolerance, and smaller ears and kernels which facilitated rapid dehydration during late grain filling.  These morphological selection criteria, which are suitable for mechanized operations, are proposed as the focus for future maize breeding.
    The rhizosphere microbial complex in plant health: A review of interaction dynamics
    Oluwaseyi Samuel OLANREWAJU, Olubukola Oluranti BABALOLA
    2022, 21(8): 2168-2182.  DOI: 10.1016/S2095-3119(21)63817-0
    Abstract ( )   PDF in ScienceDirect  
    Climate change, urbanization, and population increase limit food availability.  To sustain human existence, there is the need to increase food and agricultural production to mitigate the impact of these factors.  Scientists have been working for years on ways to increase food production.  From plant breeding techniques to soil science, scientists have made tremendous progress.  The rhizobiome has been proven to be important to crop production, and the impact of the rhizobiome on plant health cannot be overemphasized.  Being rich in diverse complex microbial interactions, the rhizosphere has become a major force in recent plant growth promotion studies.  The upsurge in next-generation sequencing applications with the various “omics” technologies is helping to unearth information relating to rhizosphere impact on plant growth.  Explaining the complex interactions between and across microbial species present in the rhizosphere is important to further enhance our understanding of their mechanistic and mutualistic functions.  Knowledge from this can be used in rhizosphere biome engineering for improved plant growth and yield in the face of the various biotic and abiotic challenges.  
    Crop Science
    Allele mining of wheat ABA receptor at TaPYL4 suggests neo-functionalization among the wheat homoeologs
    WU Bang-bang, SHI Meng-meng, Mohammad POURKHEIRANDISH, ZHAO Qi, WANG Ying, YANG Chen-kang, QIAO Ling, ZHAO Jia-jia, YAN Su-xian, ZHENG Xing-wei, ZHENG Jun
    2022, 21(8): 2183-2196.  DOI: 10.1016/S2095-3119(21)63699-7
    Abstract ( )   PDF in ScienceDirect  
    ABA receptors (PYR/PYL/RCAR) play a central role in the water loss control of plants.  A previous report indicated that TaPYL4 is a critical gene in wheat that improves grain production under drought conditions and increases water use efficiency.  In this study, we analyzed the sequence polymorphisms and genetic effects of TaPYL4s.  Based on isolated TaPYL4 genes from chromosomes 2A, 2B and 2D, three haplotypes were detected in the promoter region of TaPYL4-2A, and two haplotypes were present in TaPYL4-2B and TaPYL4-2D, respectively.  Marker/trait association analysis indicated that TaPYL4-2A was significantly associated with plant height in 262 Chinese wheat core collection accessions, as well as the drought tolerance coefficient (DTC) for plant height in 239 wheat varieties from Shanxi Province in multiple environments.  However, the frequencies of favored drought-tolerant haplotype TaPYL4-2A-Hap2 were considerably low, accounting for only 10%, and lines with this certain Hap could be reserved in the breeding program.  TaPYL4-2B was significantly associated with grain number, and the favored haplotype TaPYL4-2B-Hap1 was the dominant allele of above 90% in the collection.  For TaPYL4-2D, there were no significant differences in these traits between the two haplotypes in either of the two panels.  These results indicate that variation might lead to functional differentiation among the homoeologs and the haplotypes had undergone artificial selection during breeding.  Two molecular markers developed to distinguish these haplotypes could be used for breeding in water-limited regions.

    Characterization of chromosome segment substitution lines reveals candidate genes associated with the nodule number in soybean
    ZOU Jia-nan, ZHANG Zhan-guo, KANG Qing-lin, YU Si-yang, WANG Jie-qi, CHEN Lin, LIU Yan-ru, MA Chao, ZHU Rong-sheng, ZHU Yong-xu, DONG Xiao-hui, JIANG Hong-wei, WU Xiao-xia, WANG Nan-nan, HU Zhen-bang, QI Zhao-ming, LIU Chun-yan, CHEN Qing-shan, XIN Da-wei, WANG Jin-hui
    2022, 21(8): 2197-2210.  DOI: 10.1016/S2095-3119(21)63658-4
    Abstract ( )   PDF in ScienceDirect  
    Soybean is one of the most important food crops worldwide.  Like other legumes, soybean can form symbiotic relationships with Rhizobium species.  Nitrogen fixation of soybean via its symbiosis with Rhizobium is pivotal for sustainable agriculture.  Type III effectors (T3Es) are essential regulators of the establishment of the symbiosis, and nodule number is a feature of nitrogen-affected nodulation.  However, genes encoding T3Es at quantitative trait loci (QTLs) related to nodulation have rarely been identified. Chromosome segment substitution lines (CSSLs) have a common genetic background but only a few loci with heterogeneous genetic information; thus, they are suitable materials for identifying candidate genes at a target locus.  In this study, a CSSL population was used to identify the QTLs related to nodule number in soybean.  Single nucleotide polymorphism (SNP) markers and candidate genes within the QTLs interval were detected, and it was determined which genes showed differential expression between isolines.  Four candidate genes (GmCDPK28, GmNAC1, GmbHLH, and GmERF5) linked to the SNPs were identified as being related to nodule traits and pivotal processes and pathways involved in symbiosis establishment.  A candidate gene (GmERF5) encoding a transcription factor that may interact directly with the T3E NopAA was identified.  The confirmed CSSLs with important segments and candidate genes identified in this study are valuable resources for further studies on the genetic network and T3Es involved in the signaling pathway that is essential for symbiosis establishment. 
    Transcriptional profiling between yellow- and black-seeded Brassica napus reveals molecular modulations on flavonoid and fatty acid content
    RONG Hao, YANG Wen-jing, XIE Tao, WANG Yue, WANG Xia-qin, JIANG Jin-jin, WANG You-ping
    2022, 21(8): 2211-2226.  DOI: 10.1016/S2095-3119(21)63656-0
    Abstract ( )   PDF in ScienceDirect  

    Brassica napus is an important cash crop broadly grown for the vegetable and oil values.  Yellow-seeded Bnapus is preferred by breeders due to its improved oil and protein quality, less pigments and lignin compared with the black-seeded counterpart.  This study compared the differences in flavonoid and fatty acid contents between yellow rapeseed from the progenies of BnapusSinapis alba somatic hybrids and the black-seeded counterpart using RNA-seq analysis.  Through HPLC-PDA-ESI(−)/MS2 analysis, it was found that phenylpropanoids and flavonoids (i.e., isorhamnetin, epicatechin, kaempferol, and other derivatives) in yellow seed were significantly lower than those in black seed.  The fatty acid (FA) content in yellow rapeseed was higher than that in black rapeseed due to the variation of C16:0, C18:0, C18:1, C18:2, and C18:3 contents.  RNA-seq analysis of seeds at four and five weeks after flowering (WAF) indicated that differentially expressed genes (DEGs) between black and yellow rapeseeds were enriched in flavonoid and FA biosynthesis, including BnTT3, BnTT4, BnTT18, and BnFAD2.  Also, genes related to FA biosynthesis, desaturation and elongation (FAD3, LEC1, FUS3, and LPAT2) in yellow seed were up-regulated compared to those in black seed, while genes involved in beta-oxidation cycle (AIM1 and KAT2) of yellow seed were down-regulated compared to those in black seed.  The DEGs related to the variation of flavonoids, phenylpropanoids, and FAs would help improve the knowledge of yellow seed character in Bnapus and promote rapeseed improvement.

    An economic and viable approach to improve wheat quality in Qinghai–Tibetan Plateau, China
    WANG Yu-jiao, TAO Zhi-qiang, WANG De-mei, WANG Yan-jie, YANG Yu-shuang, ZHAO Guang-cai, SHI Shu-bing, CHANG Xu-hong
    2022, 21(8): 2227-2240.  DOI: 10.1016/S2095-3119(21)63677-8
    Abstract ( )   PDF in ScienceDirect  

    Wheat flour products are the main dietary component of the Qinghai–Tibetan Plateau (QTP) population in China.  However, the high altitude restricts the local wheat quality and quantity, and the applied nitrogen rate is higher than the optimal rate for wheat planting.  In this study, we considered whether reducing the amount of nitrogen fertilizer and introducing the superior varieties from the North China Plain (NCP) are viable ways to increase the wheat quality and quantity in the QTP.  Three and four winter wheat cultivars from QTP and NCP, respectively, were planted in Lhasa at an altitude of 3 647 m with reduced topdressing nitrogen application at the jointing stage.  The wheat from NCP exhibited higher grain hardness index and test weight, and better flour and dough quality.  Reducing the topdressing nitrogen fertilizer from 135 to 75 kg N ha−1 at the jointing stage (with the same basal fertilization of 105 kg N ha−1) did not significantly (P<0.05) affect the grain yield, grain quality, flour quality or dough quality in any of the cultivars.  In summary, introducing high-quality winter wheat varieties from the NCP to the Lhasa plateau is a viable way to enhance the wheat supply and quality in the QTP.  Reducing a certain amount of the nitrogen fertilizer is an economic and feasible approach for the QTP region.

    Growth and yield responses to simulated hail damage in drip-irrigated cotton
    WANG Le, LIU Yang, WEN Ming, LI Ming-hua, DONG Zhi-qiang, CUI Jing, MA Fu-yu
    2022, 21(8): 2241-2252.  DOI: 10.1016/S2095-3119(21)63672-9
    Abstract ( )   PDF in ScienceDirect  
    The frequent occurrence of hailstorm in Xinjiang affects cotton (Gossypium hirsutum L.) production and causes enormous economic loss.  The indeterminate growth habit of cotton allows for varying degrees of recovery and yield when different hail damage levels occur at different stages, which brings inconvenience to agricultural insurance claims and post-damage management.  Therefore, this study aimed to elucidate cotton recovery and yield responses to different levels of simulated hail damage at different growth stages.  Four levels of hail damage (0, 30, 60, and 90%) were simulated every 15 d from the five-leaf stage to the boll opening stage in 2018 and 2019, for a total of six times (I, II, III, IV, V, and VI).  The results showed that seed cotton yield decreased as the damage level increased and yield reduction increased when the damage was applied to older plants (for 30, 60 and 90% damage levels, yield reduction was 9–17%, 22–37% and 48–71%, respectively).  One possible reason was that the leaf area index and leaf area duration of plant canopy decreased after hail damage, resulting in a reduction in the accumulation of above-ground biomass.  However, when hail damage occurred before bloom, due to the indeterminate growth habit of cotton, the vegetative organs produced a strong compensation ability that promoted the bud development.  The compensation ability of vegetative organs decreased when hail damage occurred after bloom and the recovery time was too short to promote new boll maturity.  As the first study to understand the recovery of cotton after hail damage, it analyzed the leaf area index, leaf area duration, above-ground biomass accumulation and yield, rather than the yield alone.  The findings are of great importance for cotton production as they inform decisions about post-damage management practices, yield forecasts and insurance compensation.
    Identification of soft rot resistance loci in Brassica rapa with SNP markers
    LIU Meng-yang, WU Fang, GE Yun-jia, LU Yin, ZHANG Xiao-meng, WANG Yan-hua, WANG Yang, YAN Jing-hui, SHEN Shu-xing, ZHAO Jian-jun, MA Wei
    2022, 21(8): 2253-2263.  DOI: 10.1016/S2095-3119(21)63874-1
    Abstract ( )   PDF in ScienceDirect  

    Soft rot caused by Pectobacterium carotovorum (Pc) is a devastating disease of Brassica rapa, causing substantial reductions in crop yield and quality.  Identifying genes related to soft rot resistance is the key to solving this problem.  To characterize soft rot resistance, we screened a soft rot-susceptible Chinese cabbage (A03), a resistant pakchoi (‘Huaguan’), and a resistant mutant (sr).  An F2 population was generated by crossing susceptible Chinese cabbage A03 and resistant pakchoi ‘Huaguan’ to identify quantitative trait loci (QTLs) that confer soft rot resistance.  A high-density genetic map was constructed and the three QTLs identified contain 166 genes.  Based on available transcriptome data, we analyzed the expression of the 166 genes during an important defense regulatory period in Pc infection in both A03 and the resistant mutant sr.  Among the 166 genes, six candidate genes were related to the soft rot defense response in Brapa.  TIFY10B (JAZ2, BraA07g038660.3C) was located in the major soft rot resistance QTL, DRQTL-3 on A07, and we speculate that this gene may play an important role in the defense mechanism against soft rot in Brapa.  This study lays the foundation for further investigations on the mechanism of soft rot resistance in Brapa crops.

    Auxin response factor gene MdARF2 is involved in ABA signaling and salt stress response in apple
    WANG Chu-kun, ZHAO Yu-wen, HAN Peng-liang, YU Jian-qiang, HAO Yu-jin, XU Qian, YOU Chun-xiang, HU Da-gang
    2022, 21(8): 2264-2274.  DOI: 10.1016/S2095-3119(21)63843-1
    Abstract ( )   PDF in ScienceDirect  

    Auxin response factors (ARFs) play key roles throughout the whole process of plant growth and development, and mediate auxin response gene transcription by directly binding with auxin response elements (AuxREs).  However, their functions in abiotic stresses are largely limited, especially in apples.  Here, the auxin response factor gene MdARF2 (HF41569) was cloned from apple cultivar ‘Royal Gala’ (Malus×domestica Borkh.).  Phylogenetic analysis showed that ARF2 proteins are highly conserved among different species and MdARF2 is the closest relative to PpARF2 of Prunus persica, but they differ at the DNA level.  MdARF2 contains three typical conserved domains including the B3 DNA-binding domain, Auxin_resp domain and AUX_IAA domain.  The subcellular localization demonstrated that MdARF2 is localized in the nucleus.  The three-dimensional structure prediction of the proteins showed that MdARF2 is highly similar with AtARF2, and they contain helices, folds, and random coils.  The promoter of MdARF2 contains cis-acting elements which respond to various stresses, as well as environmental and hormonal signals.  Expression analysis showed that MdARF2 is widely expressed in all tissues of apple, with the highest expression of MdARF2 in root.  Functional analysis with a series of MdARF2 transgenic apple calli indicated that MdARF2 can reduce the sensitivity to ABA signaling and enhance salt tolerance in apple.  In summary, the results of this research provide a new basis for studying the regulation of abiotic stresses by ARFs.

    An assessment of the genetic diversity of pear (Pyrus L.) germplasm resources based on the fruit phenotypic traits
    ZHANG Ying, CAO Yu-fen, HUO Hong-liang, XU Jia-yu, TIAN Lu-ming, DONG Xing-guang, QI Dan, LIU Chao
    2022, 21(8): 2275-2290.  DOI: 10.1016/S2095-3119(21)63885-6
    Abstract ( )   PDF in ScienceDirect  

    Germplasm resources are an important basis for genetic breeding and analysis of complex traits, and research on genetic diversity is conducive to the exploration and creation of new types of germplasm.  In this study, the distribution frequency, coefficient of variation, Shannon–Wiener index, and variance and cluster analyses were used to analyze the diversity and trait differences of 39 fruit phenotypic traits from 570 pear accessions, which included 456 pear accessions from 11 species and 114 interspecific hybrid cultivars that had been stored in the National Germplasm Repository of Apple and Pear (Xingcheng, China).  The comprehensive evaluation indices were screened by correlation, principal component and regression analyses.  A total of 132 variant types were detected in 28 categorical traits of pear germplasm fruit, which indicate a rich diversity.  The diversity indices in decreasing order were: fruit shape (1.949), attitude of calyx (1.908), flesh texture type (1.700), persistency of calyx (1.681), russet location (1.658), relief of area around eye basin (1.644), flavor (1.610) and ground color (1.592).  The coefficient of variation of titratable acidity in the 11 numerical traits of pear germplasm fruit was as high as 128.43%, which could more effectively reflect the differences between pear accessions.  The phenotypic differentiation coefficient Vst (66.4%) among the five cultivated pear species, including Pyrus bretschneideri (White Pear), Ppyrifolia (Sand Pear), Pussuriensis (Ussurian Pear), Psinkiangensis (Xinjiang Pear), and Pcommunis (European Pear), was higher than the within population phenotypic differentiation coefficient Vst (33.6%).  The variation among populations was the main source of variation in pear fruit traits.  A hierarchical cluster analysis divided the 389 accessions of six cultivated pear species, including Ppashia (Himalayan Pear), into six categories.  There were certain characteristics within the populations, and the differences between populations were not completely clustered by region.  For example, Sand Pear cultivars from Japan and the Korean Peninsula clustered together with those from China.  Most of the White Pear cultivars clustered with the Sand Pear, and a few clustered with the Ussurian Pear cultivars.  The Ussurian Pear and European Pear cultivars clustered separately.  The Xinjiang Pear and Himalayan Pear did not cluster together, and neither did the cultivars.  Seventeen traits, three describing fruit weight and edible rate (fruit diameter, fruit length and fruit core size), five describing outer quality and morphological characteristics (over color, amount of russeting, dot obviousness, fruit shape, and stalk length), and nine describing inner quality (flesh color, juiciness of flesh, aroma, flavor, flesh texture, flesh texture type, soluble solid contents, titratable acidity, and eating quality) were selected from the 39 traits by principal component and stepwise regression analyses.  These 17 traits could reflect 99.3% of the total variation and can be used as a comprehensive evaluation index for pear germplasm resources.

    Mining of candidate genes for grape berry cracking using a genome-wide association study
    ZHANG Chuan, WU Jiu-yun, CUI Li-wen, FANG Jing-gui
    2022, 21(8): 2291-2304.  DOI: 10.1016/S2095-3119(21)63881-9
    Abstract ( )   PDF in ScienceDirect  

    Fruit cracking is a common phenomenon during the growth and development of horticultural crops that seriously affects fruit yield and quality.  However, there are few studies on the mining of candidate genes related to berry cracking.  To better understand the genetic basis of grape berry cracking, we conducted a genome-wide association study (GWAS) of grape varieties.  Based on the mixed linear model (MLM), we detected five single nucleotide polymorphism (SNP) loci associated with berry-cracking index and two SNP loci associated with berry-cracking type in two years.  These loci were mainly distributed on four chromosomes, namely 1, 2, 3, and 18, and were associated with ten unique candidate berry-cracking genes.  The gene expression patterns indicated that the candidate genes in the susceptible berry-cracking variety were more abundant than in the resistant berry-cracking variety.  Grape berry-cracking is a complex trait controlled by multiple genes, mainly including genes involved in polygalacturonase, copper transporter, and receptor-like proteins.  The high expression of the candidate berry-cracking genes may promote the occurrence of berry cracking, so the present study helps to further elucidate the genetic mechanism of berry cracking.

    Plant Protection
    Genetic analysis of adult plant, quantitative resistance to stripe rust in wheat landrace Wudubaijian in multi-environment trials
    CHAO Kai-xiang, WU Cai-juan, LI Juan, WANG Wen-li, WANG Bao-tong, LI Qiang
    2022, 21(8): 2305-2318.  DOI: 10.1016/S2095-3119(21)63876-5
    Abstract ( )   PDF in ScienceDirect  

    Stripe rust, caused by Puccinia striiformis f. sp. tritici (Pst), is one of the most destructive diseases on wheat worldwide.  Wudubaijian, a wheat landrace released from Gansu Province in China since 1950, exhibits adult-plant resistance to stripe rust for several decades.  To elucidate the genetic basis of stripe rust resistance, Wudubaijian was crossed with the high susceptible cultivar Mingxian 169, and stripe rust tests of both parents and the F2:3 lines were conducted in four environments of Yangling and Tianshui in 2015 and 2016, respectively.  The relative area under disease progress curve (rAUDPC) of Mingxian 169/Wudubaijian F2:3 lines showed that the resistance of Wudubaijian was controlled by quantitative trait loci (QTL).  Combined with phenotypic data and molecular markers, two stable QTLs were identified in Wudubaijian.  QYrwdbj.nwafu-5A with the phenotypic variance of 15.02–40.26% was located between 5AS1–0.40–0.75 and 5AS3–0.75–0.98 of chromosome 5AS, and QYrwdbj.nwafu-2B.1 with the phenotypic variance of 9.54–10.40% was located in the bin C-2BS1–0.53 of chromosome 2BS.  Through the location of flanking markers and epistasis analysis, QYrwdbj.nwafu-5A may be a new major QTL that can be used in conjunction with other stripe rust resistance genes (QTLs).

    Involvement of the autophagy-related gene BdATG8 in development and pathogenicity in Botryosphaeria dothidea
    LIU Na, LIAN Sen, ZHOU Shan-yue, WANG Cai-xia, REN Wei-chao, LI Bao-hua
    2022, 21(8): 2319-2328.  DOI: 10.1016/S2095-3119(21)63863-7
    Abstract ( )   PDF in ScienceDirect  

    Botryosphaeria dothidea is a destructive fungal pathogen that causes Botryosphaeria canker and fruit ring rot on apple worldwide.  Autophagy is a process of self-degradation that maintains intracellular homeostasis via lysosomal pathway.  To date, the biological role of autophagy in B. dothidea remains unknown.  In this study, we identified and characterized the autophagy-related gene BdATG8 in B. dothidea.  BdATG8 was able to restore the defect in nitrogen starvation tolerance of Saccharomyces cerevisiae ATG8 deletion mutant.  GFP-BdAtg8 was shown to be a useful marker for monitoring autophagy in B. dothidea.  Target deletion of BdATG8 (ΔBdAtg8) blocked autophagy and significantly impaired mycelial growth, conidiation and perithecium formation.  In addition, ΔBdAtg8 showed significantly increased sensitivity to phytoalexin and oxidative stress, suggesting that BdATG8 plays critical roles in overcoming phytoalexin and reactive oxygen species (ROS)-mediated plant immunity.  Pathogenicity assays revealed that ΔBdAtg8 almost lost ability to infect hosts.  Overall, our results indicate that BdATG8 plays an important role in fungal development, stress responses and pathogenesis in B. dothidea.

    Screening and evaluation for antibiosis resistance of the spring wheat accessions to the grain aphid, Sitobion miscanthi (Takahashi) (Hemiptera: Aphididae)
    Kifle Gebreegziabiher GEBRETSADIK, ZHANG Yong, CHEN Ju-lian
    2022, 21(8): 2329-2344.  DOI: 10.1016/S2095-3119(21)63716-4
    Abstract ( )   PDF in ScienceDirect  

    Resistant cultivar deployment is an effective method for cereal aphid management.  Under greenhouse conditions, preliminary antibiosis resistance screening was conducted on 114 Ethiopian and 22 Chinese spring wheat accessions.  After performing a bioassay to determine antibiosis resistance, aphid feeding behaviour and phenolic acid content analyses were performed on the aphid resistant wheat accessions by electrical penetration graph (EPG) and high performance liquid chromatography (HPLC), respectively.  Among the wheat accessions, two high resistances, 27 moderate-resistances, and 35 low-resistances to Sitobion miscanthi were identified.  The antibiosis resistance test showed prolonged pre-adult and pre-reproductive periods, shorter reproductive periods, lower fecundity, an intrinsic rate (rm) of increase, and a finite rate (λ) of increase of Smiscanthi on Lunxuan 145, Wane, Lunxuan 6, 204511, Lunxuan 103 and 5215 than those on the aphid-susceptible accession Beijing 837.  The changes for the parameters of aphid feeding behaviour, including spending a longer time in the penetration and phloem salivation phases and less time in the phloem sap-feeding phase on the resistant wheat accessions, the aphid resistance may occur during the phloem phase and may be due to mechanicalAdditionally, the HPLC analysis showed higher contents of: 1) ferulic acid in Lunxuan 145, Lunxuan 103 and Lunxuan 6; 2) p-coumaric acid in Lunxuan145; 3) vanillic acid in Lunxuan 145, Wane and Lunxuan 6; 4) syringic acid in Lunxuan 103; and 5) caffeic acid in 5215.  The contents of some phenolic acids within wheat leaves, such as p-courmaric acid and vanillic acid showed significant positive correlation with the duration of aphid development, but negative correlation with the aphid fecundity.  The concentrations of these acids may be the causes of antibiosis resistance to Smiscanthi.  The identification of grain aphid-resistant wheat accessions in our study will be helpful in future breeding program for pest control.

    Improved crop protection and biodiversity of the agroecosystem by reduced tillage in rice paddy fields in southern China
    LU Qi-qi, SONG Yuan-feng, PAN Ke-qing, LI Yun, TANG Ming-xin, ZHONG Guo-hua, LIU Jie
    2022, 21(8): 2345-2356.  DOI: 10.1016/S2095-3119(21)63802-9
    Abstract ( )   PDF in ScienceDirect  

    Agricultural sustainability has benefited from the broad adoption of conservation agriculture (CA) practices for decades, in which the reduction of mechanical disturbances to soil (also known as reduced tillage, RT) is one of the most essential principles for CA implementation.  Many studies have recommended the advantages of CA practices in the promotion of biodiversity, but the integrated impacts on crop productivity and biodiversity remain unclear.  Since CA has been applied in rice production in the subtropical area of southern China for several years, the effects of CA, particularly the RT methods, need to be evaluated for the local and long-term adoption.  In this study, we established an integrated network to illustrate how the reduction of tillage intensity influenced organisms including invertebrates (such as rice pests and their predators), pathogens and weeds, and then led to an impact on rice yield.  The two-year study demonstrated that major rice pests, such as rice planthoppers, stem borers and apple snails, were effectively controlled by RT practice.  Similarly, the occurrence of common diseases declined with less tillage.  Compared to the conventional tillage (CT) treatment, the density of weeds in paddy fields deceased significantly in the RT treatment.  In addition, the diversity and richness of pest predators increased remarkably in paddy fields where either reduced or no tillage was applied, which highlighted the significance of a CA strategy for the promotion of biodiversity in the agroecosystem.  More importantly, the rice yield gradually increased after the two-year reduction of tillage.  Taken together, our results suggest that the reduction of tillage intensity is beneficial for the protection of rice crops from various pests, and facilitates the sustainability of the agroecosystem and rice yield, which provides a solid basis and novel insights for the establishment of sustainable agroecosystems by CA-related practices in rice production in southern China.

    Animal Science · Veterinary Medicine
    PPAR gamma2: The main isoform of PPARγ that positively regulates the expression of the chicken Plin1 gene
    SUN Yu-hang, ZHAI Gui-ying, PANG Yong-jia, LI Rui, LI Yu-mao, CAO Zhi-ping, WANG Ning, LI Hui, WANG Yu-xiang
    2022, 21(8): 2357-2371.  DOI: 10.1016/S2095-3119(21)63896-0
    Abstract ( )   PDF in ScienceDirect  

    Perilipin1 (PLIN1) is a major phosphorylated protein that specifically coats the surface of neutral lipid droplets (LDs) in adipocytes and plays a crucial role in regulating the accumulation and hydrolysis of triacylglycerol (TG).  Mammalian studies have shown that Plin1 gene transcription is mainly regulated by peroxisome proliferator-activated receptor-gamma (PPARγ), the master regulator of adipogenesis.  However, the regulatory mechanism of the chicken Plin1 (cPlin1) gene is poorly understood.  The present study aimed to investigate whether Plin1 is regulated by PPARγ in chickens and identify its exact molecular mechanism.  Reporter gene and expression assays showed that PPARγ2, but not PPARγ1, activated (P<0.01) the cPlin1 gene promoter.  An electrophoretic mobility shift assay and mutational analysis revealed that PPARγ2 bound to a special site in the cPlin1 gene promoter to enhance its expression.  In summary, our results show that PPARγ promotes the expression of the cPlin1 gene and that PPARγ2 is the main regulatory isoform.

    Transcriptome analysis of the spleen of heterophils to lymphocytes ratio-selected chickens revealed their mechanism of differential resistance to Salmonella
    WANG Jie, ZHANG Qi, Astrid Lissette BARRETO SÁNCHEZ, ZHU Bo, WANG Qiao, ZHENG Mai-qing, LI Qing-he, CUI Huan-xian, WEN Jie, ZHAO Gui-ping
    2022, 21(8): 2372-2383.  DOI: 10.1016/S2095-3119(21)63770-X
    Abstract ( )   PDF in ScienceDirect  

    Salmonella is one of the most common food-borne pathogens and its resistance in chicken can be improved through genetic selection.  The heterophils/lymphocytes (H/L) ratio in the blood reflects the immune system status of chicken.  We compared the genome data and spleen transcriptomes between the H/L ratio-selected and non-selected chickens, after Salmonella infection, aiming to identify the key genes participating in the antibacterial activity in the spleen.  The results revealed that, the selected population had stronger (P<0.05) liver resistance to Salmonella typhimurium (ST) than the non-selected population.  In the selected and non-selected lines, the identified differentiation genes encode proteins involved in biological processes or metabolic pathways that included the TGF-beta signaling pathway, FoxO signaling pathway, and Salmonella infection pathway.  The results of the analysis of all identified differentially expressed genes (DEGs) of spleen revealed that the G protein-coupled receptor (GPCR) and insulin-like growth factor (IGF-I) signaling pathways were involved in the Salmonella infection pathway.  Integrated analysis of DEGs and FST (fixation index), identified candidate genes involved in Salmonella infection pathway, such as GPR39, NTRK2, and ANXA1.  The extensive genomic changes highlight the polygenic genetic of the immune response in these chicken populations.  Numerous genes related to the immune performance are differentially expressed in the selected and non-selected lines and the selected lines has a higher resistance to Salmonella. 

    Weighted gene co-expression network analysis identifies potential regulators in response to Salmonella Enteritidis challenge in the reproductive tract of laying ducks
    ZHANG Yu, LUO Shu-wen, HOU Li-e, GU Tian-tian, ZHU Guo-qiang, Wanwipa VONGSANGNAK, XU Qi, CHEN Guo-hong
    2022, 21(8): 2384-2398.  DOI: 10.1016/S2095-3119(21)63888-1
    Abstract ( )   PDF in ScienceDirect  

    Salmonella Enteritidis (SE) is a zoonotic and vertically transmitted pathogen, often colonized in the reproductive tract of adult poultry, which can result in direct contamination of eggs and threaten human health.  Previous studies have revealed that some pattern recognition receptors and resistance genes were involved in regulating immune responses to SE invasion in birds.  However, the role of these immune response genes was not independent, and the interactions among the genes remained to be further investigated.  In this study, SE burden and colonization were determined in reproductive tissue after the ducks were SE-infected, and RNA-sequencing was performed to construct co-expression networks by weighted gene co-expression network analysis (WGCNA).  The result showed that SE could be isolated from 22% of infected-birds in any segment of the reproductive tract and the SE was readily colonized in the stroma, small follicle, isthmus, and vagina of the reproductive tracts in morbid ducks.  The top central, highly connected genes were subsequently identified three specific modules in the above four tissues at the defined cut-offs (P<0.01), including 60 new candidate regulators and 125 transcription factors.  Moreover, those 185 differentially expressed genes (DEGs) in these modules were co-expressed.  Moreover, the hub genes (TRAF3, CXCR4 and IL13RA1) were identified to act with many other genes through immune response pathways including NF-kappaB, Toll-like receptor, steroid biosynthesis, and p53 signaling pathways.  These data provide references that will understand the immune regulatory relationships during SE infection, but also assist in the breeding of SE-resistant lines through potential biomarkers.

    Agro-ecosystem & Environment
    Low soil carbon saturation deficit limits the abundance of cbbL-carrying bacteria under long-term no-tillage maize cultivation in northern China
    YIN Tao, QIN Hong-ling, YAN Chang-rong, LIU Qi, HE Wen-qing
    2022, 21(8): 2399-2412.  DOI: 10.1016/S2095-3119(21)63800-5
    Abstract ( )   PDF in ScienceDirect  

    The responses of cbbL-carrying bacteria to different levels of soil carbon saturation deficits (SCSD) under tillage managements are largely unknown.  We assessed the influence of SCSD on the abundance and diversity of cbbL-carrying bacteria under long-term no-tillage with residue retention (NT) and conventional tillage without residue retention (CT) cultivation systems in maize.  We found SCSD was smaller under NT than under CT in the 0–15 cm soil layer.  The abundance and the Shannon diversity of cbbL-carrying bacteria in the NT treatment were lower than in the CT treatment.  Soil carbon saturation and cbbL gene abundance showed a significant positive correlation, but there was no correlation between soil carbon saturation and cbbL gene diversity.  However, the long-term NT practice decreased cbbL-carrying bacteria diversity and altered the community structure of the cbbL-carrying bacteria.  Our results indicated that low SCSD limited the abundance of cbbL-carrying bacteria, but there was no relationship between low SCSD and diversity of cbbL-carrying bacteria.  We suggest that further studies of cbbL-carrying bacteria carbon sequestration rates and capacity should be based on the effect of management practices on cbbL-carrying bacteria abundance and diversity.  Our study has important implications for the relationship between the biological and physicochemical mechanisms in CO2 fixation.

    Ammonium-dependent regulation of ammonium transporter ZmAMT1s expression conferred by glutamine levels in roots of maize
    HUI Jing, LIU Zhi, DUAN Feng-ying, ZHAO Yang, LI Xue-lian, AN Xia, WU Xiang-yu, YUAN Li-xing
    2022, 21(8): 2413-2421.  DOI: 10.1016/S2095-3119(21)63753-X
    Abstract ( )   PDF in ScienceDirect  

    In maize, two root epidermis-expressed ammonium transporters ZmAMT1;1a and ZmAMT1;3 play major roles in high-affinity ammonium uptake.  However, the transcriptional regulation of ZmAMT1s in roots for ensuring optimal ammonium acquisition remains largely unknown.  Here, using a split root system we showed that ZmAMT1;1a and ZmAMT1;3 transcript levels were induced by localized ammonium supply to nitrogen-deficient roots.  This enhanced expression of ZmAMT1s correlated with increases in 15NH4+ influx rates and tissue glutamine concentrations in roots.  When ammonium was supplied together with methionine sulfoximine, an inhibitor of glutamine synthase, ammonium-induced expression of ZmAMT1s disappeared, suggesting that glutamine rather than ammonium itself regulated ZmAMT1s expression.  When glutamine was supplied to nitrogen-deficient roots, expression levels of ZmAMT1s were enhanced, and negative feedback regulation could subsequently occur by supply of glutamine at a high level.  Thus, our results indicated an ammonium-dependent regulation of ZmAMT1s at transcript levels, and a dual role of glutamine was suggested in the regulation of ammonium uptake in maize roots.

    Predicting soil depth in a large and complex area using machine learning and environmental correlations
    LIU Feng, YANG Fei, ZHAO Yu-guo, ZHANG Gan-lin, LI De-cheng
    2022, 21(8): 2422-2434.  DOI: 10.1016/S2095-3119(21)63692-4
    Abstract ( )   PDF in ScienceDirect  

    Soil depth is critical for eco-hydrological modeling, carbon storage calculation and land evaluation.  However, its spatial variation is poorly understood and rarely mapped.  With a limited number of sparse samples, how to predict soil depth in a large area of complex landscapes is still an issue.  This study constructed an ensemble machine learning model, i.e., quantile regression forest, to quantify the relationship between soil depth and environmental conditions.  The model was then combined with a rich set of environmental covariates to predict spatial variation of soil depth and straightforwardly estimate the associated predictive uncertainty in the 140 000 km2 Heihe River basin of northwestern China.  A total of 275 soil depth observation points and 26 covariates were used.  The results showed a model predictive accuracy with coefficient of determination (R2) of 0.587 and root mean square error (RMSE) of 2.98 cm (square root scale), i.e., almost 60% of soil depth variation explained.  The resulting soil depth map clearly exhibited regional patterns as well as local details.  Relatively deep soils occurred in low lying landscape positions such as valley bottoms and plains while shallow soils occurred in high and steep landscape positions such as hillslopes, ridges and terraces.  The oases had much deeper soils than outside semi-desert areas, the middle of an alluvial plain had deeper soils than its margins, and the middle of a lacustrine plain had shallower soils than its margins.  Large predictive uncertainty mainly occurred in areas with a lack of soil survey points.  Both pedogenic and geomorphic processes contributed to the shaping of soil depth pattern of this basin but the latter was dominant.  This findings may be applicable to other similar basins in cold and arid regions around the world.

    Food Science
    Plant-based meat substitutes by high-moisture extrusion: Visualizing the whole process in data systematically from raw material to the products
    ZHANG Jin-chuang, MENG Zhen, CHENG Qiong-ling, LI Qi-zhai, ZHANG Yu-jie, LIU Li, SHI Ai-min, WANG Qiang
    2022, 21(8): 2435-2444.  DOI: 10.1016/S2095-3119(21)63892-3
    Abstract ( )   PDF in ScienceDirect  

    High-moisture extrusion technology should be considered one of the best choices for producing plant-based meat substitutes with the rich fibrous structure offered by real animal meat products.  Unfortunately, the extrusion process has been seen as a “black box” with limited information about what occurs inside, causing serious obstacles in developing meat substitutes.  This study designed a high-moisture extrusion process and developed 10 new plant-based meat substitutes comparable to the fibrous structure of real animal meat.  The study used the Feature-Augmented Principal Component Analysis (FA-PCA) method to visualize and understand the whole extrusion process in three ways systematically and accurately.  It established six sets of mathematical models of the high-moisture extrusion process based on 8 000 pieces of data, including five types of parameters.  The FA-PCA method improved the R2 values significantly compared with the PCA method.  The Way 3 was the best to predict product quality (Z), demonstrating that the gradually molecular conformational changes (Yn´) were critical in controlling the final quality of the plant-based meat substitutes.  Moreover, the first visualization platform software for the high-moisture extrusion process has been established to clearly show the “black box” by combining the virtual simulation technology.  Through the software, some practice work such as equipment installation, parameter adjustment, equipment disassembly, and data prediction can be easily achieved.

    Effects of grape seed extract on meat color and premature browning of meat patties in high-oxygen packaging
    YANG Xiao-yin, XU Bao-chen, LEI Hong-mei, LUO Xin, ZHU Li-xian, ZHANG Yi-min, MAO Yan-wei, LIANG Rong-rong
    2022, 21(8): 2445-2455.  DOI: 10.1016/S2095-3119(21)63854-6
    Abstract ( )   PDF in ScienceDirect  

    This study investigated the effects of grape seed extract (GSE) on fresh and cooked meat color and premature browning (PMB) in ground meat patties (85% beef and 15% pork back fat) packaged under high-oxygen modified atmospheres (HiOx-MAP).  The GSE was added to patties at concentrations of 0, 0.10, 0.25, 0.50 and 0.75 g kg–1.  This study evaluated the surface color, pH, lipid oxidation, and total viable counts (TVC) of raw patties, and the internal color and pH of patties cooked to a temperature of 66 or 71°C over 10-day storage at 4°C.  Compared with the control (0 g kg–1 GSE), GSE improved the color stability (P<0.05) and significantly inhibited the lipid and myoglobin oxidation of raw patties from day 5 to 10, but GSE had no effect (P>0.05) on TVC.  Patties containing 0.50 and 0.75 g kg–1 GSE cooked to 66°C exhibited greater (P<0.05) interior redness than the control and reduced the PMB of cooked patties in the late storage stage.  These results suggested that 0.50 and 0.75 g kg–1 GSE can improve fresh meat color and minimize PMB of HiOx-MAP patties.

    Short Communication
    Construction of chimeric viruses based on pepper mild mottle virus using a modified Cre/loxP system
    YIN Yue-yan, HUA Meng-ying, ZHAO Kuang-jie, WAN Qiong-lian, BU Shan, LU Yu-wen, ZHENG Hong-ying, RAO Shao-fei, YAN Fei, PENG Jie-jun, CHEN Hai-ru, CHEN Jian-ping
    2022, 21(8): 2456-2463.  DOI: 10.1016/S2095-3119(21)63864-9
    Abstract ( )   PDF in ScienceDirect  

    Cre/loxP, a site-specific recombination system, has been widely used for various purposes, including chromosomal translocations, generation of marker-free transgenic plants, tissue-specific activation of a reporter gene and efficient heterologous gene expression in plants.  However, stable or transient expression of Cre recombinase in plants can cause chlorosis or necrosis.  Here, we describe a modified Cre/loxP recombination system using a DNA fragment flanked with loxP sites in the same orientation in which necrosis induced by Cre recombinase in Nicotiana benthamiana leaves was alleviated.  The modified system was successfully used to create functional GFP-tagged pepper mild mottle virus (PMMoV) and a chimeric virus with coat protein (CP) substitution assembled from separate pro-vector modules.  Our results provide a new strategy and flexible technique to construct chimeric virus and infectious clones for plant viruses with large genomes.