2022 Vol. 21 No. 6 Previous Issue   
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Crop Science
Genetic diversity analysis and GWAS reveal the adaptive loci of milling and appearance quality of japonica (oryza sativa L.) in Northeast China
XU Xin, YE Jun-hua, YANG Ying-ying, LI Ruo-si, LI Zhen, WANG Shan, SUN Yan-fei, ZHANG Meng-chen, XU Qun, FENG Yue, WEI Xing-hua, YANG Yao-long
2022, 21(6): 1539-1550.  DOI: 10.1016/S2095-3119(21)63701-2
Abstract ( )   PDF in ScienceDirect  
Milling and appearance quality are important contributors to rice grain quality.  Abundant genetic diversity and a suitable environment are crucial for rice improvement.  In this study, we investigated the milling and appearance quality-related traits in a panel of 200 japonica rice cultivars selected from Liaoning, Jilin and Heilongjiang provinces in Northeast China.  Pedigree assessment and genetic diversity analysis indicated that cultivars from Jilin harbored the highest genetic diversity among the three geographic regions.  An evaluation of grain quality indicated that cultivars from Liaoning showed superior milling quality, whereas cultivars from Heilongjiang tended to exhibit superior appearance quality.  Single- and multi-locus genome-wide association studies (GWAS) were conducted to identify loci associated with milling and appearance quality-related traits.  Ninety-nine significant single-nucleotide polymorphisms (SNPs) were detected.  Three common SNPs were detected using the mixed linear model (MLM), mrMLM, and FASTmrMLM methods.  Linkage disequilibrium decay was estimated and indicated three candidate regions (qBRR-1, qBRR-9 and qDEC-3) for further candidate gene analysis.  More than 300 genes were located in these candidate regions.  Gene Ontology (GO) analysis was performed to discover the potential candidate genes.  Genetic diversity analysis of the candidate regions revealed that qBRR-9 may have been subject to strong selection during breeding.  These results provide information that will be valuable for the improvement of grain quality in rice breeding.
A major and stable QTL for wheat spikelet number per spike validated in different genetic backgrounds
DING Pu-yang, MO Zi-qiang, TANG Hua-ping, MU Yang, DENG Mei, JIANG Qian-tao, LIU Ya-xi, CHEN Guang-deng, CHEN Guo-yue, WANG Ji-rui, LI Wei, QI Peng-fei, JIANG Yun-feng, KANG Hou-yang, YAN Gui-jun, Wei Yu-ming, ZHENG You-liang, LAN Xiu-jin, MA Jian
2022, 21(6): 1551-1562.  DOI: 10.1016/S2095-3119(20)63602-4
Abstract ( )   PDF in ScienceDirect  
The spikelet number per spike (SNS) contributes greatly to grain yield in wheat.  Identifying various genes that control wheat SNS is vital for yield improvement.  This study used a recombinant inbred line population genotyped by the Wheat55K single-nucleotide polymorphism array to identify two major and stably expressed quantitative trait loci (QTLs) for SNS.  One of them (QSns.sau-2SY-2D.1) was reported previously, while the other (QSns.sau-2SY-7A) was newly detected and further analyzed in this study.  QSns.sau-2SY-7A had a high LOD value ranging from 4.46 to 16.00 and explained 10.21–40.78% of the phenotypic variances.  QSns.sau-2SY-7A was flanked by the markers AX-110518554 and AX-110094527 in a 4.75-cM interval on chromosome arm 7AL.  The contributions and interactions of both major QTLs were further analyzed and discussed.  The effect of QSns.sau-2SY-7A was successfully validated by developing a tightly linked kompetitive allele specific PCR marker in an F2:3 population and a panel of 101 high-generation breeding wheat lines.  Furthermore, several genes including the previously reported WHEAT ORTHOLOG OF APO1 (WAPO1), an ortholog of the rice gene ABERRANT PANICLE ORGANIZATION 1 (APO1) related to SNS, were predicted in the interval of QSns.sau-2SY-7A.  In summary, these results revealed the genetic basis of the multi-spikelet genotype of wheat line 20828 and will facilitate subsequent fine mapping and breeding utilization of the major QTLs.
The GhMAX2 gene regulates plant growth and fiber development in cotton
HE Peng, ZHANG Hui-zhi, ZHANG Li, JIANG Bin, XIAO Guang-hui, YU Jia-ning
2022, 21(6): 1563-1575.  DOI: 10.1016/S2095-3119(21)63603-1
Abstract ( )   PDF in ScienceDirect  
Strigolactones (SLs) are a new type of plant endogenous hormones that have been found to regulate plant growth and architecture.  At present, some genes related to the biosynthesis and signaling pathway of SLs have been isolated in plants such as Arabidopsis thaliana, Pisum sativum and Oryza sativa.  However, the signaling pathway and specific mechanism of SLs in cotton remain unclear.  In this study, we identified the SLs signaling gene GhMAX2 and demonstrated its function in plant growth and architecture in Gossypium hirsutum.  Bioinformatics analysis showed that GhMAX2 mainly consists of an α-helix and a random coil and includes a large number of leucine-rich repeats.  GhMAX2 was highly expressed in root, stem, flower, and fibers at 20 days post-anthesis (DPA).  GhMAX2 promoter-driven β-glucuronidase expression was present exclusively in the root, main inflorescence, flower, and silique.  Subcellular localization showed that GhMAX2 is targeted to the nucleus.  Heterologously expressed GhMAX2 can rescue the phenotype of Arabidopsis max2-1 mutant, indicating that the function of MAX2 is highly conserved between G. hirsutum and A. thaliana species.  In addition, the knockdown expression of GhMAX2 in cotton resulted in significantly reduced plant height, slow growth, short internodes, and reduced fiber length.  These findings indicate that GhMAX2 probably contributes to plant growth, architecture and fiber elongation in cotton. The study reveals insights into the roles of GhMAX2-mediated SL/KAR signaling in cotton and provides a valuable foundation for the cultivation of cotton plants in the future.
Optimization of nitrogen fertilization improves rice quality by affecting the structure and physicochemical properties of starch at high yield levels
ZHOU Tian-yang, LI Zhi-kang, LI En-peng, WANG Wei-lu, YUAN Li-min, ZHANG Hao, LIU Li-jun, WANG Zhi-qin, GU Jun-fei, YANG Jian-chang
2022, 21(6): 1576-1592.  DOI: 10.1016/S2095-3119(21)63678-X
Abstract ( )   PDF in ScienceDirect  
A major challenge in modern rice production is to achieve the dual goals of high yield and good quality with low environmental costs.  This study was designed to determine whether optimized nitrogen (N) fertilization could fulfill these multiple goals.  In two-year experiments, two high yielding ‘super’ rice cultivars were grown with different N fertilization management regimes, including zero N input, local farmers’ practice (LFP) with heavy N inputs, and optimized N fertilization (ONF).  In ONF, by reducing N input, increasing planting density, and optimizing the ratio of urea application at different stages, N use efficiency and the physicochemical and textural properties of milled rice were improved at higher yield levels.  Compared with LFP, yield and partial factor productivity of applied N (PFP) under ONF were increased (on average) by 1.70 and 13.06%, respectively.  ONF increased starch and amylose content, and significantly decreased protein content.  The contents of the short chains of A chain (degree of polymerization (DP) 6–12) and B1 chain (DP 13–25) of amylopectin were significantly increased under ONF, which resulted in a decrease in the stability of rice starch crystals.  ONF increased viscosity values and improved the thermodynamic properties of starch, which resulted in better eating and cooking quality of the rice.  Thus, ONF could substantially compensate the negative effects caused by N fertilizer and achieve the multiple goals of higher grain quality and nitrogen use efficiency (NUE) at high yield levels.  These results will be useful for applications of high quality rice production at high yield levels.
Source–sink relations and responses to sink–source manipulations during grain filling in wheat
WU Xiao-li, LIU Miao, LI Chao-su, Allen David (Jack) MCHUGH, LI Ming, XIONG Tao, LIU Yu-bin, TANG Yong-lu
2022, 21(6): 1593-1605.  DOI: 10.1016/S2095-3119(21)63640-7
Abstract ( )   PDF in ScienceDirect  
The source–sink ratio during grain filling is a critical factor that affects crop yield in wheat, and the main objective of this study was to determine the source–sink relations at both the canopy scale and the individual culm level under two nitrogen (N) levels at the post-jointing stage.  Nine widely-used cultivars were chosen for analyzing source–sink relations in southwestern China; and three typical cultivars of different plant types were subjected to artificial manipulation of the grain-filling source–sink ratio to supplement crop growth measurements.  A field experiment was conducted over two consecutive seasons under two N rates (N+, 150 kg ha–1; N–, 60 kg ha–1), and three manipulations were imposed after anthesis: control (Ct), removal of flag and penultimate leaves (Lr) and removal of spikelets on one side of each spike (Sr).  The results showed that the single grain weights in the three cultivars were significantly decreased by Lr and increased by Sr, which demonstrated that wheat grain yield potential seems more source-limited than sink-limited during grain filling, but the source–sink balance was obviously changed by climatic variations and N deficient environments.  Grain yield was highly associated with sink capacity (SICA), grain number, biomass, SPAD values, and leaf area index during grain filling, indicating a higher degree of source limitation with an increase in sink capacity.  Therefore, source limitation should be taken into account by breeders when SICA is increased, especially under non-limiting conditions.  Chuanmai 104, a half-compact type with a mid-sized spike and a long narrow upper leaf, showed relatively better performance in source–sink relations.  Since this cultivar showed the characteristics of a lower reduction in grain weight after Lr, a larger increase after Sr, and a lower reduction in post-anthesis dry matter accumulation, then the greater current photosynthesis during grain filling contributed to the grain after source and sink manipulation. 
Image-based root phenotyping for field-grown crops: An example under maize/soybean intercropping
HUI Fang, XIE Zi-wen, LI Hai-gang, GUO Yan, LI Bao-guo, LIU Yun-ling, MA Yun-tao
2022, 21(6): 1606-1619.  DOI: 10.1016/S2095-3119(20)63571-7
Abstract ( )   PDF in ScienceDirect  
Root architecture, which determines the water and nutrient uptake ability of crops, is highly plastic in response to soil environmental changes and different cultivation patterns.  Root phenotyping for field-grown crops, especially topological trait extraction, is rarely performed.  In this study, an image-based semi-automatic root phenotyping method for field-grown crops was developed.  The method consisted of image acquisition, image denoising and segmentation, trait extraction and data analysis.  Five global traits and 40 local traits were extracted with this method.  A good consistency in 1st-order lateral root branching was observed between the visually counted values and the values extracted using the developed method, with R2=0.97.  Using the method, we found that the interspecific advantages for maize mainly occurred within 5 cm from the root base in the nodal roots of the 5th–7th nodes, and that the obvious inhibition of soybean was mostly reflected within 20 cm from the root base.  Our study provides a novel approach with high-throughput and high-accuracy for field research on root morphology and branching features.  It could be applied to the 3D reconstruction of field-grown root system architecture to improve the inputs to data-driven models (e.g., OpenSimRoot) that simulate root growth, solute transport and water uptake.
Genome-wide identification, evolutionary selection, and genetic variation of DNA methylation-related genes in Brassica rapa and Brassica oleracea
AN Feng, ZHANG Kang, ZHANG Ling-kui, LI Xing, CHEN Shu-min, WANG Hua-sen, CHENG Feng
2022, 21(6): 1620-1632.  DOI: 10.1016/S2095-3119(21)63827-3
Abstract ( )   PDF in ScienceDirect  
DNA methylation plays an important role in plant growth and development, and in regulating the activity of transposable elements (TEs).  Research on DNA methylation-related (DMR) genes has been reported in Arabidopsis, but little research on DMR genes has been reported in Brassica rapa and Brassica oleracea, the genomes of which exhibit significant differences in TE content.  In this study, we identified 78 and 77 DMR genes in Brassica rapa and Brassica oleracea, respectively.  Detailed analysis revealed that the numbers of DMR genes in different DMR pathways varied in B. rapa and B. oleracea.  The evolutionary selection pressure of DMR genes in B. rapa and B. oleracea was compared, and the DMR genes showed differential evolution between these two species.  The nucleotide diversity (π) and selective sweep (Tajima’s D) revealed footprints of selection in the B. rapa and B. oleracea populations.  Transcriptome analysis showed that most DMR genes exhibited similar expression characteristics in B. rapa and B. oleracea.  This study dissects the evolutionary differences and genetic variations of the DMR genes in B. rapa and B. oleracea, and will provide valuable resources for future research on the divergent evolution of DNA methylation between B. rapa and B. oleracea.
Effects of exogenous paclobutrazol and sampling time on the efficiency of in vitro embryo rescue in the breeding of new seedless grape varieties
XU Teng-fei, GUO Yu-rui, YUAN Xiao-jian, CHU Yan-nan, WANG Xiao-wei, HAN Yu-lei, WANG Wen-yuan, WANG Yue-jin, SONG Rui, FANG Yu-lin, WANG Lu-jun, XU Yan
2022, 21(6): 1633-1644.  DOI: 10.1016/S2095-3119(21)63815-7
Abstract ( )   PDF in ScienceDirect  

Embryo rescue technology plays an important role in seedless grape breeding.  However, the efficiency of embryo rescue, including the embryo formation, germination, and seedling rates, is closely related to the parental genotypes, degree of abortion, growth medium, and plant growth regulators.  In this study, we investigated the effects of different concentrations of paclobutrazol (PAC), a plant growth regulator, and embryo collection times on the embryo formation, germination, and seedling rates for different hybrid combinations of grape breeding varieties used for their aroma and cold-resistance traits.  The results showed that the different PAC concentrations had varying impacts on the development of ovules and embryos from the different grape varieties.  The embryo formation rates of the ‘Sultanina Rose’בBeibinghong’ and ‘Kunxiang Seedless’בTaishan-2’ crosses were the highest under the 5.1 μmol L–1 PAC treatment.  The 1.0 μmol L–1 PAC treatment was optimal for the germination and seedling development of the ‘Sultanina Rose’בBeibinghong’ embryos, whereas the 0.2 μmol L–1 PAC treatment induced the highest germination rate for the ‘Sultanina Rose’בKunxiang Seedless’ cross.  The optimal sampling times for each cross varied as 39 d after pollination (DAP) for the ‘Flame Seedless’בMuscat Hamburg’ cross, 46 DAP for the ‘Kunxiang Seedless’בBeibinghong’ cross, and 41 DAP for the ‘Ruby Seedless’בBeibinghong’ and ‘Fantasy Seedless’בShuangyou’ crosses.  Moreover, the medium modified with 0.5 g L–1 of indole-3-butyric acid allowed the malformed seedlings to develop into plantlets and achieve larger progenies.  This study provides a useful basis for further studies into grape embryo rescue and could improve breeding efforts for new seedless grape varieties.

PbPH5, an H+ P-ATPase on the tonoplast, is related to malic acid accumulation in pear fruit
SONG Jun-xing, CHEN Ying-can, LU Zhao-hui, ZHAO Guang-ping, WANG Xiao-li, ZHAI Rui, WANG Zhi-gang, YANG Cheng-quan, XU Ling-fei
2022, 21(6): 1645-1657.  DOI: 10.1016/S2095-3119(21)63790-5
Abstract ( )   PDF in ScienceDirect  

Organic acids are one of the most important factors influencing fruit flavors. The predominant organic acid in most pear cultivars is malic acid, but the mechanism controlling its accumulation remains unclear. In this study, by comparing gene expression levels and organic acid content, we revealed that the expression of PbPH5, which encodes a P3A-ATPase, is highly correlated with malic acid accumulation in different pear species, with correlation coefficients of 0.932**, 0.656*, 0.900**, and 0.518* (*, P<0.05 or **, P<0.01) in Pyrus bretschneideri Rehd., P. communis Linn., P. pyrifolia Nakai., and P. ussuriensis Maxim., respectively. Moreover, the overexpression of PbPH5 in pear significantly increased the malic acid content. In contrast, silencing PbPH5 via RNA interference significantly decreased its transcript level and the pear fruit malic acid content. A subcellular localization analysis indicated that PbPH5 is located in the tonoplast. Additionally, a phylogenetic analysis proved that PbPH5 is a PH5 homolog gene that is clustered with Petunia hybrida, Malus domestica, and Citrus reticulata genes. Considered together, these findings suggest PbPH5 is a functionally conserved gene. Furthermore, the accumulation of malic acid in pear fruits is at least partly related to the changes in PbPH5 transcription levels.

Genome-wide characterization and expression analysis of WRKY family genes during development and resistance to Colletotrichum fructicola in cultivated strawberry (Fragaria×ananassa Duch.)
ZOU Xiao-hua, DONG Chao, LIU Hai-ting, GAO Qing-hua
2022, 21(6): 1658-1672.  DOI: 10.1016/S2095-3119(21)63816-9
Abstract ( )   PDF in ScienceDirect  
Based on the recently published whole-genome sequence of cultivated strawberry ‘Camarosa’, in this study, 222 FaWRKY genes were identified in the ‘Camarosa’ genome.  Phylogenetic analysis showed that the 222 FaWRKY candidate genes were classified into three groups, of which 41 were in group I, 142 were in group II, and 39 were in group III.  The 222 FaWRKY genes were evenly distributed among the seven chromosomes.  The exon–intron structures and motifs of the WRKY genes had evolutionary diversity in different cultivated strawberry genomes.  Regarding differential expression, the expression of FaWRKY133 was relatively high in leaves, while FaWRKY63 was specifically expressed in roots.  FaWRKY207, 59, 46, 182, 156, 58, 39, 62 and 115 were up-regulated during achene development from the green to red fruit transition.  FaWRK181, 166 and 211 were highly expressed in receptacles at the ripe fruit stage.  One interesting finding was that FaWRKY179 and 205 were significantly repressed after Colletotrichum fructicola inoculation in both ‘Benihoppe’ and ‘Sweet Charlie’ compared with Mock.  The data reported here provide a foundation for further comparative genomics and analyses of the distinct expression patterns of FaWRKY genes in various tissues and in response to C. fructicola inoculation.
Plant Protection
A transferred regulator that contributes to Xanthomonas oryzae pv. oryzicola oxidative stress adaptation and virulence by regulating the expression of cytochrome bd oxidase genes
WANG Pei-hong, WANG Sai, NIE Wen-han, WU Yan, Iftikhar AHMAD, Ayizekeranmu YIMING, HUANG Jin, CHEN Gong-you, ZHU Bo
2022, 21(6): 1673-1682.  DOI: 10.1016/S2095-3119(21)63801-7
Abstract ( )   PDF in ScienceDirect  
Horizontal gene transfer (HGT) has been well documented as a driving force in the evolution of bacteria.  It has been shown that a horizontally acquired gene, xoc_2868, involved in the global response against oxidative stress and pathogenicity of Xanthomonas oryzae pv. oryzicola strain BLS256.  However, as a transcriptional factor (TF), the regulatory mechanism of XOC_2868 has not yet been revealed.  Here, evolutionary analysis suggested XOC_2868 might be co-transferred with its physically proximate downstream genes from a Burkholderiaceae ancestor.  Interestingly, RNA-seq data of wild-type (BLS256) and Δxoc_2868 strains under oxidative stress showed that XOC_2868 did not regulate the expression of its adjacent genes, but remarkably influenced the expression of several genes involved in the extracellular polysaccharide (EPS) production and xanthan biosynthesis.  Chromatin immunoprecipitation-sequence (ChIP-seq) combined with transcriptome analysis revealed that XOC_2868 directly regulates a cydAB operon, encoding two subunits of cytochrome bd oxidase and involved in redox balance.  Consistent with Δxoc_2868 strain, cydA- and cydAB-knockout mutants also showed a higher sensitivity to H2O2 along with a reduced bacterial virulence compared with the wild-type strain.  Overall, our findings raise the possibility of regulatory circuit evolution shaped by HGT and driven by selection and reveal a novel regulatory pathway that regulates the expression of cytochrome bd oxidase and thus contributes to the virulence of BLS256.  
A rapid multiplication system for 'Candidatus Liberibacter asiaticus' through regeneration of axillary buds in vitro
LEI Tian-gang, HE Yong-rui, ZOU Xiu-ping, WANG Xue-feng, FU Shi-min, PENG Ai-hong, XU Lan-zhen, YAO Li-xiao, CHEN Shan-chun, ZHOU Chang-yong
2022, 21(6): 1683-1693.  DOI: 10.1016/S2095-3119(21)63856-X
Abstract ( )   PDF in ScienceDirect  
Candidatus Liberibacter asiaticus (CLas)’, which causes citrus Huanglongbing (HLB) disease, has not been successfully cultured in vitro to date. Here, a rapid multiplication system for CLas was established through in vitro regeneration of axillary buds from CLas-infected ‘Changyecheng’ sweet orange (Citrus sinensis Osbeck). Firstly, stem segments with a single axillary bud were cultured in vitro to allow CLas to multiply in the regenerating axillary buds. A high CLas titer was detected in the regenerated shoots on an optimized medium at 30 days after germination (DAG), and it was 28.2-fold higher than in the midribs from CLas-infected trees growing in the greenhouse. To minimize contamination during in vitro regeneration, CLas-infected axillary buds were micrografted onto seedlings of ‘Changyecheng’ sweet orange and cultured in a liquid medium. In this culture, the titers of CLas in regenerated shoots rapidly increased from 7.5×104 to 1.4×108 cells μg-1 of citrus DNA during the first 40 DAG. The percentages of shoots with >1×108 CLas cells μg-1 DNA were 30% and 40% at 30 and 40 DAG, respectively. Direct tissue blot immune assay (DTBIA) indicated that the distribution of CLas was much more uniform in regenerated plantlets than in CLas-infected trees growing in the greenhouse. The disease symptoms in the plantlets were die-back, stunted growth, leaf necrosis/yellowing, and defoliation. The death rate of the plantlets was 82.0% at 60 DAG. Our results show that CLas can effectively multiply in in vitro culture. This method will be useful for studying plant–HLB interactions and for rapid screening of therapeutic compounds against CLas in citrus.
Identification of Heterodera schachtii on sugar beet in Xinjiang Uygur Autonomous Region of China
PENG Huan, LIU Hui, GAO Li, JIANG Ru, LI Guang-kuo, GAO Hai-feng, Wu Wei, WANG Jun, Zhang Yu, HUANG Wen-kun, KONG Ling-an, PENG De-liang
2022, 21(6): 1694-1702.  DOI: 10.1016/S2095-3119(21)63797-8
Abstract ( )   PDF in ScienceDirect  
The sugar beet cyst nematode, Heterodera schachtii, is a major parasite of sugar beet which has been recognized and listed as a quarantine nematode in China and more than 20 countries and regions worldwide.  A survey for important nematodes was undertaken in the sugar beet planting area of China during 2015–2018, and numerous cysts were collected from sugar beet fields in Xinyuan County, Xinjiang Uygur Autonomous Region of China.  The observations of morphological and morphometric characteristics revealed that cysts, vulval cones and second-stage juveniles of the Xinjiang population were in the same range of each other and within those of other reported H. schachtii populations.  Molecular analysis of rDNA-ITS, 28S-D2/D3 and mtDNA cytochrome c oxidase subunit 1 (COI) gene sequences suggested that the Xinjiang population clustered in a branch with those foreign populations, and the sequence similarity was as high as 99.81–100%.  Moreover, this result was confirmed by PCR assay with species-specific primer SHF6 and rDNA2 of H. schachtii, and the pathogenicity test confirmed successful Xinjiang population reproduction in both plant hosts.  In conclusion, based on morphological and molecular characterization, this study confirmed that the cyst nematode population collected from sugar beet fields in Xinjiang is H. schachtii.  As far as we know, this is the first report of H. schachtii on sugar beets in Xinjiang, China.
Physiological mitochondrial ROS regulate diapause by enhancing HSP60/Lon complex stability in Helicoverpa armigera
ZHANG Xiao-shuai, SU Xiao-long, GENG Shao-lei, WANG Zheng-hao
2022, 21(6): 1703-1712.  DOI: 10.1016/S2095-3119(20)63578-X
Abstract ( )   PDF in ScienceDirect  
Diapause is a long-lived stage which has evolved into an important strategy for insects to circumvent extreme environments.  In the pupal stage, Helicoverpa armigera can enter diapause, a state characterized by significantly decreased metabolic activity and enhanced stress resistance, to survive cold winters.  Previous studies have shown that reactive oxygen species (ROS) can promote the diapause process by regulating a distinct insulin signaling pathway.  However, the source of ROS in the diapause-destined pupal brains and mechanisms by which ROS regulate diapause are still unknown.  In this study, we showed that diapause-destined pupal brains accumulated high levels of mitochondrial ROS (mtROS) and total ROS during the diapause process, suggesting that mitochondria are the main source of ROS in diapause-destined pupal brains.  In addition, injection of 2-deoxy-D-glucose (DOG), a glucose metabolism inhibitor, could delay pupal development by elevating mtROS levels in the nondiapause-destined pupal brains.  Furthermore, the injection of a metabolite mixture to increase metabolic activity could avert the diapause process in diapause-destined pupae by decreasing mtROS levels.  We also found that ROS could activate HSP60 expression and promote the stability of the HSP60-Lon complex, increasing its ability to degrade mitochondrial transcription factor A (TFAM) and decreasing mitochondrial activity or biogenesis under oxidative stress.  Thus, this study illustrated the beneficial function of ROS in diapause or lifespan extension by decreasing mitochondrial activity.
Characterization of carboxylesterase PxαE8 and its role in multi-insecticide resistance in Plutella xylostella (L.)
LI Ran, SUN Xi, LIANG Pei, GAO Xi-wu
2022, 21(6): 1713-1721.  DOI: 10.1016/S2095-3119(21)63636-5
Abstract ( )   PDF in ScienceDirect  
Carboxylesterases (CarEs) were considered as important phase-I detoxifying enzymes which participated in detoxification of different types of insecticides.  Up-regulation of CarE genes has been proved playing a major role in insecticide resistance in many pest insects, but its involvement in resistance to insecticides in Plutella xylostella has been rarely reported.  In this study, a CarE cDNA named PxαE8 was identified in P. xylostella, which has an open reading frame of 1599 nucleotides and putatively encodes 532 amino acids.  The investigation of spatial and temporal expression profiles of PxαE8 revealed that it was expressed in all developmental stages and body part/tissues, especially in larvae, adults as well as fat body, malpighian tubule and hemolymph of larvae.  Further, the relative expression of PxαE8 in two multi-resistant field populations, Hainan (HN) and Guangdong (GD) populations, was found 24.4- and 15.5-fold higher than that in susceptible population, respectively.  Knockdown of PxαE8 by RNAi dramatically increased the mortalities of larvae of HN population treated with LC50 of beta-cypermethrin and phoxim by 25.3 and 18.3%, respectively.  These results suggested that up-regulation of PxαE8 was involved in resistance to both beta-cypermethrin and phoxim in P. xylostella, which shed light on further understanding of molecular mechanisms of multi-insecticide-resistance in P. xylostella and other pest insects.
High temperatures do not decrease biocontrol potential for the host-killing parasitoid Neochrysocharis formosa (Hymenoptera: Eulophidae) on agromyzid leafminers
XUAN Jing-li, XIAO Yue, YE Fu-yu, ZHANG Yi-bo, TAO Shu-xia, GUO Jian-yang, LIU Wan-xue
2022, 21(6): 1722-1730.  DOI: 10.1016/S2095-3119(21)63727-9
Abstract ( )   PDF in ScienceDirect  
Temperature, as a critical abiotic factor, might influence the effectiveness of biological control by parasitoids in host-parasitoid systems. In this study, Neochrysocharis formosa (Westwood), a larval endoparasitoid, is used to investigate the efficacy of biological control on a vegetable agriculture pest, Liriomyza sativae Blanchard, reared on kidney bean (Phaseolus vulgaris L.), at four constant temperatures (26, 29, 32, and 35°C) under laboratory conditions. Our results show that high temperatures (29, 32, and 35°C) do not significantly affect lifetime host-killing events of female adults by increased daily host-killing events compared to temperature 26°C, although their lifespans decrease with an increase in temperatures. Each life-history trait of female adults (lifespan, parasitism, stinging, or nonreproductive host-killing events) present a linear relation with temperatures and host-feeding events, respectively. Our findings contribute to a better understanding of biocontrol efficacy of parasitoid N. formosa against agromyzid leafminers at high-temperature seasons or environments.
Animal Science · Veterinary Medicine
Epigenome-wide DNA methylation analysis reveals differentially methylation patterns in skeletal muscle between Chinese Chenghua and Qingyu pigs
WANG Kai, WU Ping-xian, WANG Shu-jie, JI Xiang, CHEN Dong, JIANG An-an, XIAO Wei-hang, JIANG Yan-zhi, ZHU Li, ZENG Yang-shuang, XU Xu, QIU Xiao-tian, LI Ming-zhou, LI Xue-wei, TANG Guo-qing
2022, 21(6): 1731-1739.  DOI: 10.1016/S2095-3119(21)63814-5
Abstract ( )   PDF in ScienceDirect  
Chenghua (CH) pig and Qingyu (QY) pig are typical Chinese native fatty breeds.  CH pig is mainly distributed in Chengdu Plain, while QY pig is widely distributed throughout the mountain areas around the Sichuan Basin.  There are significant differences in their phenotypic traits, including body image, growth performance, and meat quality.  This study compared several meat quality traits of CH and QY pigs and conducted a genome-wide DNA methylation analysis using reduced representation bisulfite sequencing (RRBS).  It was observed that the pH at 45 min (pH45min, P=5.22e–13), lightness at 45 min (L*45min, P=4.85e–5), and lightness at 24 h (L*24h, P=3.57e–5) of CH pigs were higher than those of QY pigs.  We detected 10 699 differentially methylated cytosines (DMCs) and 2 760 differentially methylated genes (DMGs) associated with these DMCs.  Functional analysis showed that these DMGs were mainly enriched in the AMPK signaling pathway, Type II diabetes mellitus, Insulin signaling pathway, mTOR signaling pathway, and Insulin resistance.  Furthermore, 15 DMGs were associated with fat metabolism (ACACA, CAB39, CRADD, CRTC2, FASN, and GCK), muscle development (HK2, IKBKB, MTOR, PIK3CD, PPARGC1A, and RPTOR), or meat quality traits (PCK1, PRKAG2, and SLC2A4).  The findings may help to understand further the epigenetic regulation mechanisms of meat quality traits in pigs and provide new basic data for the study of local pigs.
HBP1 inhibits chicken preadipocyte differentiation by activating the STAT3 signaling via directly enhancing JAK2 expression
CHEN Hong-yan, CHENG Bo-han, MA Yan-yan, ZHANG Qi, LENG Li, WANG Shou-zhi, LI Hui
2022, 21(6): 1740-1754.  DOI: 10.1016/S2095-3119(21)63895-9
Abstract ( )   PDF in ScienceDirect  

Obesity presents a serious threat to human health and broiler performance.  The expansion of adipose tissue is mainly regulated by the differentiation of preadipocytes.  The differentiation of preadipocytes is a complex biological process regulated by a variety of transcription factors and signaling pathways.  Previous studies have shown that the transcription factor HMG-box protein 1 (HBP1) can regulate the differentiation of mouse 3T3-L1 preadipocytes by activating the Wnt/β-catenin signaling pathway.  However, it is unclear whether HBP1 involved in chicken preadipocyte differentiation and which signaling pathways it regulates.  The aim of the current study was to explore the biological function and molecular regulatory mechanism of HBP1 in the differentiation of chicken preadipocytes.  The expression patterns of chicken HBP1 in abdominal adipose tissue and during preadipocyte differentiation were analyzed by RT-qPCR and Western blot.  The preadipocyte stably overexpressing HBP1 or knockout HBP1 and their control cell line were used to analyze the effect of HBP1 on preadipocyte differentiation by oil red O staining, RT-qPCR and Western blot.  Cignal 45-Pathway Reporter Array was used to screen the signal pathways that HBP1 regulates in the differentiation of chicken preadipocytes.  Chemical inhibitor and siRNA for signal transducer and activator of transcription 3 (STAT3) were used to analyze the effect of STAT3 on preadipocyte differentiation.  The preadipocyte stably overexpressing HBP1 was transfected by the siRNA of STAT3 or treated with a chemical inhibitor of STAT3 for the rescue experiment.  The results of gene expression analysis showed that the expression of HBP1 was related to abdominal fat deposition and preadipocyte differentiation in chickens.  The results of function gain and loss experiments indicated that overexpression/knockout of HBP1 in chicken preadipocytes could inhibit/promote (P<0.05) lipid droplet deposition and the expression of adipogenesis-related genes.  Mechanismlly, HBP1 activates (P<0.05) the signal transducer and activator of transcription 3 (STAT3) signaling pathway by targeting janus kinase 2 (JAK2) transcription.  The results of functional rescue experiments indicated that STAT3 signaling mediated the regulation of HBP1 on chicken preadipocyte differentiation.  In conclusion, HBP1 inhibits chicken preadipocyte differentiation by activating the STAT3 signaling pathway via directly enhancing JAK2 expression.  Our findings provided new insights for further analysis of the molecular genetic basis of chicken adipose tissue growth and development.

Agro-ecosystem & Environment
Maizelegume intercropping promote N uptake through changing the root spatial distribution, legume nodulation capacity, and soil N availability
ZHENG Ben-chuan, ZHOU Ying, CHEN Ping, ZHANG Xiao-na, DU Qing, YANG Huan, WANG Xiao-chun, YANG Feng, XIAO Te, LI Long, YANG Wen-yu, YONG Tai-wen
2022, 21(6): 1755-1771.  DOI: 10.1016/S2095-3119(21)63730-9
Abstract ( )   PDF in ScienceDirect  
Legume cultivars affect N uptake, component crop growth, and soil physical and chemical characteristics in maize–legume intercropping systems.  However, how belowground interactions mediate root growth, N fixation, and nodulation of different legumes to affect N uptake is still unclear.  Hence, a two-year experiment was conducted with five planting patterns, i.e., maize–soybean strip intercropping (IMS), maize–peanut strip intercropping (IMP), and corresponding monocultures (monoculture maize (MM), monoculture soybean (MS), and monoculture peanut (MP)), and two N application rates, i.e., no N fertilizer (N–) and conventional N fertilizer (N+), to examine relationships between N uptake and root distribution of crops, legume nodulation and soil N availability.  Results showed that the averaged N uptake per unit area of intercrops was significantly lower than the corresponding monocultures.  Compared with the monoculture system, the N uptake of the intercropping systems increased by 31.7–45.4% in IMS and by 7.4–12.2% in IMP, respectively.  The N uptake per plant of intercropped maize and soybean significantly increased by 61.6 and 31.8%, and that of intercropped peanuts significantly decreased by 46.6% compared with the corresponding monocultures.  Maize and soybean showed asymmetrical distribution of roots in strip intercropping systems.  The root length density (RLD) and root surface area density (RSAD) of intercropped maize and soybean were significantly greater than that of the corresponding monocultures.  The roots of intercropped peanuts were confined, which resulted in decreased RLD and RSAD compared with the monoculture.  The nodule number and nodule fresh weight of soybean were significantly greater in IMS than in MS, and those of peanut were significantly lower in IMP than in MP.  The soil protease, urease, and nitrate reductase activities of maize and soybean were significantly greater in IMS and IMP than in the corresponding monoculture, while the enzyme activities of peanut were significantly lower in IMP than in MP.  The soil available N of maize and soybean was significantly greater increased in IMS and IMP than in the corresponding monocultures, while that of IMP was significantly lower than in MP.  In summary, the IMS system was more beneficial to N uptake than the IMP system.  The intercropping of maize and legumes can promote the N uptake of maize, thus reducing the need for N application and improving agricultural sustainability.

Integrated management of crop residue and nutrients enhances new carbon formation by regulating microbial taxa and enzymes
WU Hong-liang, CAI An-dong, XING Ting-ting, HUAI Sheng-chang, ZHU Ping, HAN Xiao-zeng, XU Ming-gang, LU Chang-ai
2022, 21(6): 1772-1785.  DOI: 10.1016/S2095-3119(21)63752-8
Abstract ( )   PDF in ScienceDirect  
Although returning crop residue to fields is a recommended measure for improving soil carbon (C) stocks in agroecosystems, the response of newly formed soil C (NFC) to the integrated supply of residue and nutrients and the microbial mechanisms have not been fully understood. Therefore, an 84-day incubation experiment was conducted to ascertain the microbial mechanisms that underpin the NFC response to inputs of residue and nitrogen (N), phosphorus (P), and sulfur (S) in two black soils. The results showed that adding residue alone accelerated microbial nutrient mining, which was supported by decreases of 8–16% in the ratios of C:N and C:P enzyme activities (relative to soils with nutrient inputs). The NFC amounts increased from 1155.9 to 1722.4 mg kg−1 soil in Gongzhuling and increased from 725.1 to 1067.5 mg kg−1 soil in Hailun as the levels of nutrient supplementation increased. Boosted regression tree analysis suggested that β-glucosidase (BG), acid phosphatase (AP), microbial biomass C (MBC), and Acidobacteria accounted for 27.8, 18.5, 14.7, and 8.1%, respectively, of the NFC in Gongzhuling and accounted for 25.9, 29.5, 10.1, and 13.9%, respectively, of the NFC in Hailun. Path analysis determined that Acidobacteria positively influenced NFC both directly and indirectly by regulating BG, AP, and MBC, in which MBC acquisition was regulated more by AP. The intensity of NFC was lower in Hailun soil than in Gongzhuling soil and was directly affected by AP, thereby indicating the importance of soil status (e.g., SOC and pH) in determining NFC. Overall, our results reveal the response of NFC to supplementation by N, P, and S, which depends on Acidobacteria and Proteobacteria, and their investment in BG and AP in residue-amended soil.
From statistics to grids: A two-level model to simulate crop pattern dynamics
XIA Tian, WU Wen-bin, ZHOU Qing-bo, Peter H. VERBURG, YANG Peng, HU Qiong, YE Li-ming, ZHU Xiao-juan
2022, 21(6): 1786-1789.  DOI: 10.1016/S2095-3119(21)63713-9
Abstract ( )   PDF in ScienceDirect  
Crop planting patterns are an important component of agricultural land systems.  These patterns have been significantly changed due to the combined impacts of climatic changes and socioeconomic developments.  However, the extent of these changes and their possible impacts on the environment, terrestrial landscapes and rural livelihoods are largely unknown due to the lack of spatially explicit datasets including crop planting patterns.  To fill this gap, this study proposes a new method for spatializing statistical data to generate multitemporal crop planting pattern datasets.  This method features a two-level model that combines a land-use simulation and a crop pattern simulation.  The output of the first level is the spatial distribution of the cropland, which is then used as the input for the second level, which allocates crop censuses to individual gridded cells according to certain rules.  The method was tested using data from 2000 to 2019 from Heilongjiang Province, China, and was validated using remote sensing images.  The results show that this method has high accuracy for crop area spatialization.  Spatial crop pattern datasets over a given time period can be important supplementary information for remote sensing and thus support a wide range of application in agricultural land systems.
Agricultural Economics and Management
ICT-based agricultural advisory services and nitrogen management practices: A case study of wheat production in China
DING Ji-ping, LI Jing-han, LIU Jia-huan, ZHANG Wei-feng, JIA Xiang-ping
2022, 21(6): 1799-1811.  DOI: 10.1016/S2095-3119(21)63859-5
Abstract ( )   PDF in ScienceDirect  
Excessive use of nitrogen fertilizer in China and its adverse effects on agricultural production have been a national and global concern. In addition to massive public initiatives to promote sustainable farm practices, grass-rooted innovations are emerging in the niche, many of which take the forms of information and communication technologies (ICT) and digital services. This study examines the effects of ICT-based extension services provided by an entrepreneurial startup on adopting sustainable farming practices. We found no significant reduction in N-fertilizer use for wheat production. But the ICT-based services promoted farmers to adapt N-fertilizer use towards site-specific management. The business model of the entrepreneurial venture faces great challenges in becoming participatory and financially sustainable.

Agricultural production structure, market conditions and farmers' nutritional intake in rural China
WAN Yue, HU Hao, Wuyang HU
2022, 21(6): 1812-1824.  DOI: 10.1016/S2095-3119(21)63873-X
Abstract ( )   PDF in ScienceDirect  

Nutrition poverty alleviation is an effective measure to improve the nutritional status of economically disadvantaged individuals, fundamentally improving their health and reducing poverty.  Based on the Entitlement Theory and using the China Health and Nutrition Survey (CHNS) data, this paper examines the relationship between farmers’ nutritional intake, production structure and regional market conditions.  Results show that farmers with diversified production have better nutritional intake than those who specialize.  Furthermore, the correlation between regional market conditions and nutritional intake varies between economically disadvantaged and non-economically disadvantaged households.  Market conditions significantly influence the carbohydrate and fat intake of economically disadvantaged households and are positively associated with the dietary structure and nutritional intake of non-economically disadvantaged ones.  Moreover, income is positively correlated with the nutritional intake of non-economically disadvantaged households but not with economically disadvantaged ones.  

Short Communication
First record of the little fire ant, Wasmannia auropunctata (Hymenoptera: Formicidae), in Chinese mainland
CHEN Si-qi, ZHAO Yi, LU Yong-yue, RAN Hao, XU Yi-juan
2022, 21(6): 1825-1829.  DOI: 10.1016/S2095-3119(22)63903-0
Abstract ( )   PDF in ScienceDirect  
In January 2022, we received ant specimens collected from three field colonies from Shantou City, Guangdong Province, China.  They were identified as the little fire ant, Wasmannia auropunctata, through morphological and molecular analyses.  Wasmannia auropunctata is listed as one of the 100 most dangerous invasive species by the International Union for Conservation of Nature (IUCN) and has spread from its native range in South America to every continent except Antarctica.  DNA analysis of mitochondrial cytochrome c oxidase subunit I (COI) in nine specimens of W. auropunctata found that they had a close genetic relationship with specimens from Argentina.  This study represents the first formal record of the establishment of W. auropunctata outdoor in Chinese mainland.  However, the invasion stage and occurrence degree of W. auropunctata in China are not clear to date.  The implementation of quarantine measures, investigation of the occurrence and distribution, and development of monitoring and control strategies are needed to actively respond to the threat posed by this highly invasive ant.
Investigation of Mitochondrial DNA genetic diversity and phylogeny of goats worldwide
GUO Yi, GONG Ying, HE Yong-meng, YANG Bai-gao, ZHANG Wei-yi, CHEN Bo-er, HUANG Yong-fu, ZHAO Yong-ju, ZHANG Dan-ping, MA Yue-hui, CHU Ming-xing, E Guang-xin
2022, 21(6): 1830-1837.  DOI: 10.1016/S2095-3119(21)63882-0
Abstract ( )   PDF in ScienceDirect  
Genetic diversity, population structure, and population expansion of goats worldwide (4 165 individuals from 196 breeds) were analyzed using published mitochondrial DNA (mtDNA) D_loop hypervariable region sequences. Results showed that 2 409 haplotypes and 301 polymorphic sites were present within the 401-bp length D_loop region, the nucleotide diversity (Pi) was 0.03471, and the haplotype diversity (Hd) was 0.9983. Phylogenetic analysis revealed that 98.92% of haplotypes were divided into six obvious clusters, consistent with the classification of the known mitochondrial haplogroups of goats. Haplogroup A accounted for the largest proportion (86%). Interestingly, two unknown divisions (Unknown I and Unknown II) were discovered from goats in Southwest China, suggesting that Southwest China has unique maternal haplogroups. Analysis of molecular variance (AMOVA) and the average number of pairwise differences between populations (PiXY) indicated that geographical variation was small but significant. Neutrality tests (Tajima’s D and Fu’s FS tests) and mismatch distribution showed that haplogroups B, C, and G had expansion histories. In addition, the phylogenetic relationship between domestic and wild goats suggested that Capra aegagrus is the most likely wild ancestor and may have participated in the domestication of ancestral populations of A, B, C, and F haplogroups. A meta-analysis on the mtDNA sequences of goats from international databases was conducted to analyze goats’ genetic diversity, population structure, and matrilineal system evolution worldwide. The results may help further understand the domestication history and gene flow of goats worldwide.