BACKGROUND:Cotton fiber length and strength are both key traits of fiber quality, and fiber strength (FS) is tightly correlated with secondary cell wall (SCW) biosynthesis. The three-amino-acid-loop-extension (TALE) superclass homeoproteins are involved in regulating diverse biological processes in plants, and some TALE members has been identified to play a key role in regulating SCW formation. However, little is known about the functions of TALE members in cotton (Gossypium spp.). RESULTS:In the present study, based on gene homology, 46, 47, 88 and 94 TALE superfamily genes were identified in G. arboreum, G. raimondii, G. barbadense and G. hirsutum, respectively. Phylogenetic and evolutionary analysis showed the evolutionary conservation of two cotton TALE families (including BEL1-like and KNOX families). Gene structure analysis also indicated the conservation of GhTALE members under selection. The analysis of promoter cis-elements and expression patterns suggested potential transcriptional regulation functions in fiber SCW biosynthesis and responses to some phytohormones for GhTALE proteins. Genome-wide analysis of colocalization of TALE transcription factors with SCW-related QTLs revealed that some BEL1-like genes and KNAT7 homologs may participate in the regulation of cotton fiber strength formation. Overexpression of GhKNAT7-A03 and GhBLH6-A13 significantly inhibited the synthesis of lignocellulose in interfascicular fibers of Arabidopsis. Yeast two-hybrid (Y2H) experiments showed extensive heteromeric interactions between GhKNAT7 homologs and some GhBEL1-like proteins. Yeast one-hybrid (Y1H) experiments identified the upstream GhMYB46 binding sites in the promoter region of GhTALE members and defined the downstream genes that can be directly bound and regulated by GhTALE heterodimers. CONCLUSION:We comprehensively identified TALE superfamily genes in cotton. Some GhTALE members are predominantly expressed during the cotton fiber SCW thicking stage, and may genetically correlated with the formation of FS. Class II KNOX member GhKNAT7 can interact with some GhBEL1-like members to form the heterodimers to regulate the downstream targets, and this regulatory relationship is partially conserved with Arabidopsis. In summary, this study provides important clues for further elucidating the functions of TALE genes in regulating cotton growth and development, especially in the fiber SCW biosynthesis network, and it also contributes genetic resources to the improvement of cotton fiber quality.

Artemisia argyi L. is a widely distributed medicinal plant in China. The major bioactive substances of essential oils extracted from leaves are terpenoids. Although many researches have studied the pharmacological effects of the essential oils, the tissue-specific accumulation of terpenoid biosynthesis and the regulatory networks in A. argyi are poorly understood. This study conducted an integrated metabolomic and transcriptomic analysis of roots, stems, and leaves to investigate the tissue-specific regulatory network of terpenoid biosynthesis in A. argyi. We identified 77 unigenes putatively involved in terpenoid backbone biosynthesis. Three rate-determining enzyme genes (DXS, DXR, and HDR) of the methylerythritol phosphate pathway were predominantly expressed in leaves, and strongly co-expressed with eight transcription factors (2 MYBs, 4 WRKYs, and 2 AP2s). An metabolite-transcript correlation analysis revealed 26 putative cytochrome P450s related to terpenoid metabolism in leaves. These results provide a foundation for the future metabolic engineering of useful terpenoids in A. argyi.

SUMMARYHybrid breakdown (HB) functions as a common reproductive barrier and reduces hybrid fitness in many species, including cotton. However, the related genes and the underlying genetic mechanisms of HB in cotton remain unknown. Here, we found that the photosensitive genetic male sterile line CCRI9106 was a hybrid progeny of Gossypium hirsutum and Gossypium barbadense and probably a product of HB. Fine mapping with F2s (CCRI9106 × G. hirsutum/G. barbadense lines) identified a pair of male sterility genes GoFLA19s (encoding fasciclin‐like arabinogalactan family protein) located on chromosomes A12 and D12. Crucial variations occurring in the fasciclin‐like domain and the arabinogalactan protein domain were predicted to cause the non‐functionalization of GbFLA19‐D and GhFLA19‐A. CRISPR/Cas9‐mediated knockout assay confirmed the effects of GhFLA19s on male sterility. Sequence alignment analyses showed that variations in GbFLA19‐D and GhFLA19‐A likely occurred after the formation of allotetraploid cotton species. GoFLA19s are specifically expressed in anthers and contribute to tapetal development, exine assembly, intine formation, and pollen grain maturation. RNA‐sequencing and quantitative reverse transcriptase–polymerase chain reaction analyses illustrated that genes related to these biological processes were significantly downregulated in the mutant. Our research on male sterility genes, GoFLA19s, improves the understanding of the molecular characteristics and evolutionary significance of HB in interspecific hybrid breeding.

Background: Male sterility is a simple and efficient pollination control system that is widely exploited in hybrid breeding. In upland cotton, CCRI9106, a photosensitive genetic male sterile (PGMS) mutant isolated from CCRI040029, was reported of great advantages to cotton heterosis. However, little information concerning the male sterility of CCRI9106 is known. Here, comparative transcriptome analysis of CCRI9106 (the mutant, MT) and CCRI040029 (the wild type, WT) anthers in Anyang (long-day, male sterile condition to CCRI9106) was performed to reveal the potential male sterile mechanism of CCRI9106. Results: Light and electron microscopy revealed that the male sterility phenotype of MT was mainly attributed to irregularly exine, lacking tryphine and immature anther cuticle. Based on the cytological characteristics of MT anthers, anther RNA libraries (18 in total) of tetrad (TTP), late uninucleate (lUNP) and binucleate (BNP) stages in MT and WT were constructed for transcriptomic analysis, therefore revealing a total of 870,4 differentially expressed genes (DEGs). By performing gene expression pattern analysis and protein-protein interaction (PPI) networks construction, we found down-regulation of DEGs, which enriched by the lipid biosynthetic process and the synthesis pathways of several types of secondary metabolites such as terpenoids, flavonoids and steroids, may crucial to the male sterility phenotype of MT, and resulting in the defects of anther cuticle and tryphine, even the irregularly exine. Furthermore, several lipid-related genes together with ABA-related genes and MYB transcription factors were identified as hub genes via weighted gene co-expression network analysis (WGCNA). Additionally, the ABA content of MT anthers was reduced across all stages when compared with WT anthers. At last, genes related to the formation of anther cuticle and tryphine could activated in MT under short-day condition. Conclusions: We propose that the down-regulation of genes related to the assembly of anther cuticle and tryphine may lead to the male sterile phenotype of MT, and MYB transcription factors together with ABA played key regulatory roles in these processes. The conversion of fertility in different photoperiods may closely relate to the functional expression of these genes. These findings contribute to elucidate the mechanism of male sterility in upland cotton.

Verticillium wilt will seriously affect cotton yield and fiber quality. BEL1-Like transcription factors are involved in the regulation of secondary cell wall (SCW) formation, especially the biosynthesis of lignin that also plays a key role in cotton disease resistance. However, there is no report on the role of BEL1-Like transcription factor in the regulation of plant biological stress. In this study, tissue expression pattern analysis showed that a BEL1-Like transcription factor GhBLH7-D06 was predominantly expressed in vascular tissues and the SCW thickening stage of fiber development, while its expression could also respond to Verticillium dahliae infection and the phytohormone MeJA treatment, which indicated that GhBLH7-D06 might be involved in the defense response of Verticillium wilt. Using virus-induced gene silencing (VIGS) technology, we found silencing the expression of GhBLH7-D06 could enhance the resistance of cotton plants to Verticillium wilt, and the acquisition of resistance might be mainly due to the significant overexpression of genes related to lignin biosynthesis and JA signaling pathway, which also proves that GhBLH7-D06 negatively regulates the resistance of cotton to Verticillium wilt. Based on the results of yeast two-hybrid (Y2H) library screening and confirmation by bimolecular fluorescence complementary (BiFC) experiment, we found an Ovate Family Protein (OFP) transcription factor GhOFP3-D13 which was also a negative regulator of cotton Verticillium wilt resistance could that interacts with GhBLH7-D06. Furthermore, the dual-luciferase reporter assay and yeast one-hybrid (Y1H) experiment indicated that GhBLH7-D06 could target binding to the promoter region of GhPAL-A06 to suppress its expression and eventually lead to the inhibition of lignin biosynthesis. In general, the GhBLH7-D06/GhOFP3-D13 complex can negatively regulate resistance to Verticillium wilt of cotton by inhibiting lignin biosynthesis and JA signaling pathway.

Background Valine-glutamine ( VQ ) motif-containing proteins play important roles in plant growth, development and abiotic stress response. For many plant species, the VQ genes have been identified and their functions have been described. However, little is known about the origin, evolution, and functions (and underlying mechanisms) of the VQ family genes in cotton. Results In this study, we comprehensively analyzed the characteristics of 268 VQ genes from four Gossypium genomes and found that the VQ proteins evolved into 10 clades, and each clade had a similar structural and conservative motif. The expansion of the VQ gene was mainly through segmental duplication, followed by dispersal. Expression analysis revealed that many GhVQs might play important roles in response to salt and drought stress, and GhVQ18 and GhVQ84 were highly expressed under PEG and salt stress. Further analysis showed that GhVQs were co-expressed with GhWRKY transcription factors (TFs), and microRNAs (miRNAs) could hybridize to their cis-regulatory elements. Conclusions The results in this study broaden our understanding of the VQ gene family in plants, and the analysis of the structure, conserved elements, and expression patterns of the VQs provide a solid foundation for exploring their specific functions in cotton responding to abiotic stresses. Our study provides significant insight into the potential functions of VQ genes in cotton.

SummaryThe transition from vegetative to reproductive growth is very important for early maturity in cotton. However, the genetic control of this highly dynamic and complex developmental process remains unclear. A high‐resolution tissue‐ and stage‐specific transcriptome profile was generated from six developmental stages using 72 samples of two early‐maturing and two late‐maturing cotton varieties. The results of histological analysis of paraffin sections showed that flower bud differentiation occurred at the third true leaf stage (3TLS) in early‐maturing varieties, but at the fifth true leaf stage (5TLS) in late‐maturing varieties. Using pairwise comparison and weighted gene co‐expression network analysis, 5312 differentially expressed genes were obtained, which were divided into 10 gene co‐expression modules. In the MElightcyan module, 46 candidate genes regulating cotton flower bud differentiation were identified and expressed at the flower bud differentiation stage. A novel key regulatory gene related to flower bud differentiation, GhCAL, was identified in the MElightcyan module. Anti‐GhCAL transgenic cotton plants exhibited late flower bud differentiation and flowering time. GhCAL formed heterodimers with GhAP1‐A04/GhAGL6‐D09 and regulated the expression of GhAP1‐A04 and GhAGL6‐D09. GhAP1‐A04‐ and GhAGL6‐D09‐silenced plants also showed significant late flowering. Finally, we propose a new flowering regulatory pathway mediated by GhCAL. This study elucidated the molecular mechanism of cotton flowering regulation and provides good genetic resources for cotton early‐maturing breeding.

Key message The vsp gene was fine mapped to a 353.7-kb region, and a 201-bp deletion that affected chloroplast development and chlorophyll biosynthesis was found in the candidate gene GhPUR4 . Abstract Virescent mutations can be used as marker traits in heterosis breeding and can also be used to research chloroplast development, chlorophyll biosynthesis and photosynthesis mechanisms. Here, we obtained a light-sensitive virescent mutant, vsp , that has reduced chlorophyll (Chl) content and abnormal chloroplast development. Then, the virescent space ( vsp ) gene in the vsp mutant was preliminarily mapped to a 38.32-Mb region of chromosome D04 using a high-density SNP genetic map with a total length of 5384.33 cM and 4472 bin markers. Furthermore, the vsp gene was narrowed down to a 353.7-kb region that contains 15 candidate genes using 484 virescent individuals from an F 2 population. Sequence analysis of genes in this region showed that a 201-bp deletion was present in the Gh_D04G1108 ( GhPUR4 ) gene in the vsp mutant. The 201-bp deletion of Gh_D04G1108 caused the deletion of 67 AAs in the GhPUR4 protein. Virus-induced gene silencing (VIGS) of GhPUR4 in normal plants caused reduced GhPUR4 gene expression levels, reduced Chl content, abnormal chloroplast development and virescent true leaves. This study could help us unravel the function of GhPUR4 in chloroplast development and Chl biosynthesis at the early developmental stages of the true leaves in cotton, which could promote the research and application of virescent mutations in cotton heterosis breeding.

The young leaves of virescent mutants are yellowish and gradually turn green as the plants reach maturity. Understanding the genetic basis of virescent mutants can aid research of the regulatory mechanisms underlying chloroplast development and chlorophyll biosynthesis, as well as contribute to the application of virescent traits in crop breeding. In this study, fine mapping was employed, and a recessive gene (v 1) from a virescent mutant of Upland cotton was narrowed to an 84.1-Kb region containing ten candidate genes. The GhChlI gene encodes the cotton Mg-chelatase I subunit (CHLI) and was identified as the candidate gene for the virescent mutation using gene annotation. BLAST analysis showed that the GhChlI gene has two copies, Gh_A10G0282 and Gh_D10G0283. Sequence analysis indicated that the coding region (CDS) of GhChlI is 1269 bp in length, with three predicted exons and one non-synonymous nucleotide mutation (G1082A) in the third exon of Gh_D10G0283, with an amino acid (AA) substitution of arginine (R) to lysine (K). GhChlI-silenced TM-1 plants exhibited a lower GhChlI expression level, a lower chlorophyll content, and the virescent phenotype. Analysis of upstream regulatory elements and expression levels of GhChlI showed that the expression quantity of GhChlI may be normal, and with the development of the true leaf, the increase in the Gh_A10G0282 dosage may partially make up for the deficiency of Gh_D10G0283 in the v 1 mutant. Phylogenetic analysis and sequence alignment revealed that the protein sequence encoded by the third exon of GhChlI is highly conserved across diverse plant species, in which AA substitutions among the completely conserved residues frequently result in changes in leaf color in various species. These results suggest that the mutation (G1082A) within the GhChlI gene may cause a functional defect of the GhCHLI subunit and thus the virescent phenotype in the v1 mutant. The GhChlI mutation not only provides a tool for understanding the associations of CHLI protein function and the chlorophyll biosynthesis pathway but also has implications for cotton breeding.

Background: Pectin is a major component and structural polysaccharide of the primary cell walls and middle lamella of higher plants. Pectate lyase (PEL, EC 4.2.2.2), a cell wall modification enzyme, degrades de-esterified pectin for cell wall loosening, remodeling and rearrangement. Nevertheless, there have been few studies on PEL genes and no comprehensive analysis of the PEL gene family in cotton. Results: We identified 53, 42 and 83 putative PEL genes in Gossypium raimondii (D5), Gossypium arboreum (A2), and Gossypium hirsutum (AD1), respectively. These PEL genes were classified into five subfamilies (I-V). Members from the same subfamilies showed relatively conserved gene structures, motifs and protein domains. An analysis of gene chromosomal locations and gene duplication revealed that segmental duplication likely contributed to the expansion of the GhPELs. The 2000 bp upstream sequences of all the GhPELs contained auxin response elements. A transcriptomic data analysis showed that 62 GhPELs were expressed in various tissues. Notably, most (29/32) GhPELs of subfamily IV were preferentially expressed in the stamen, and five GhPELs of subfamily V were prominently expressed at the fiber elongation stage. In addition, qRT-PCR analysis revealed the expression characteristics of 24 GhPELs in four pollen developmental stages and significantly different expression of some GhPELs between long and short-fiber cultivars. Moreover, some members were responsive to IAA treatment. The results indicate that GhPELs play significant and functionally diverse roles in the development of different tissues. Conclusions: In this study, we comprehensively analyzed PELs in G. hirsutum, providing a foundation to better understand the functions of GhPELs in different tissues and pathways, especially in pollen, fiber and the auxin signaling pathway.

基于常山胡柚生产者视角,利用常山胡柚主产区胡柚种植农户的调研数据,通过建立Logistic模型,重点分析了原产地保护标识下常山胡柚生产收益的制约因素.结果表明,在以原产地、市场销售和组织化等为特征的指标体系下,常山胡柚传统文化认知、胡柚市场需求、胡柚价格优势、销售渠道、订单生产等变量对农户收益期望有显著的正向影响.此外,农户年龄、种植规模、种植年限对农户收益期望有显著的正向影响.而原产地标签变量不显著则表明农户对原产地保护标识的认知程度较低,原产地保护措施并未拉动胡柚种植户增收效应的提升.

Premature leaf senescence occurs in the ultimate phase of the plant, and it occurs through a complex series of actions regulated by stress, hormones and genes. In this study, a proteomic analysis was performed to analyze the factors that could induce premature leaf senescence in two cotton cultivars. We successfully identified 443 differential abundant proteins (DAPs) from 7388 high-confidence proteins at four stages between non-premature senescence (NS) and premature senescence (PS), among which 158 proteins were over-accumulated, 238 proteins were down-accumulated at four stages, and 47 proteins displayed overlapped accumulation. All the DAPs were mapped onto 21 different categories on the basis of a Clusters of Orthologous Groups (COG) analysis, and 9 clusters were based on accumulation. Gene Ontology (GO) enrichment results show that processes related to stress responses, including responses to cold temperatures and responses to hormones, are significantly differentially accumulated. More importantly, the enriched proteins were mapped in The Arabidopsis Information Resource (TAIR), showing that 58 proteins play an active role in abiotic stress, hormone signaling and leaf senescence. Among these proteins, 26 cold-responsive proteins (CRPs) are significantly differentially accumulated. The meteorological data showed that the median temperatures declined at approximately 15 days before the onset of aging, suggesting that a decrease in temperature is tightly linked to an onset of cotton leaf senescence. Because accumulations of H2O2 and increased jasmonic acid (JA) were detected during PS, we speculate that two pathways associated with JA and H2O2 are closely related to premature leaf senescence in cotton.

基于中国动态可计算一般均衡(CGE)模型,系统探讨了极端气候冲击下中国粮食安全的最优技术进步路径选择.从产量、价格、进口依赖度以及人均占有量的视角综合考察了粮食安全指标的动态变化,结论表明:土地、劳动力和资本增进型技术进步会缓解极端气候对粮食安全的不利冲击,并且缓解的效果依次递减;土地和劳动增进型技术进步组合、土地和资本增进型技术进步组合、劳动力和资本增进型技术进步组合缓解极端气候对粮食安全冲击的效果也依次递减.提出:在当前小规模经营农户为主的条件下,为了缓解极端气候事件对粮食安全的不利冲击,粮食生产应重点鼓励土地增进型技术进步,其次是劳动力增进型技术进步.

本文在中国CGE模型中引入劳动力市场分割因素,兼顾生产要素的互补性和替代性关系,从供给和需求两个层面探讨了人口结构变迁对中国粮食安全的影响.研究发现,随着人口老龄化和人口城镇化的推进,中国粮食安全同时受到供给与需求层面的持久负面冲击:在所有模拟情景中,人口结构变迁均导致粮食价格上涨、进口依赖度增加以及人均粮食占有量下降;而仅当生产要素为替代关系且劳动力市场不存在分割时,人口结构变迁才会在长期内导致国内粮食产量增加.这表明在人口结构变迁的背景下,进一步消除劳动力在行业间流动的障碍是提升粮食安全的有效途径.

At present,export of mainland China's citrus is under pressure from the maximum residue limits of pesticides standard,especially the high standard of developed countries and regions,to a certain degree,restricts the export capacity of citrus in mainland China.This paper analyzes the current situation of flow and flow direction of mainland China's citrus export:export of citrus in general shows the increasing tendency in the process of fluctuation;the intensity of export market is high,variety and export flow are short of diversity and huge trade risk exists;mainland China's citrus export mainly flows to Asia and the occupancy rate in European and American markets is quite low.The comparision of importing citrus MRLs system among different countries and regions shows that the gap of maximum residue limits of pesticides of citrus between mainland China and developed countries and regions in testing types and testing standard is very large,which will easily results in technical trade barrier for mainland China's citrus export.However,standard of residue limits of pesticides in developing countries and regions of southeastern Asia is slightly lower than that of mainland China,which to a certain extent,reduces the possibility of trade friction of mainland China's citrus in these areas.Based on analysis of using the gravity model,this paper finds that standard of residue limits of pesticides in importing countries and regions has become an important obstacle which greatly influences mainland China's citrus export trade.Consequently,this paper proposes several policy suggestions on how to neutralize such technical barriers:to build the citrus MRLs system joining up with international system,push forward the standardized production of citrus industry and establish perfect citrus MRLs warning mechanism.

本文以高等农林院校经济管理专业本科学生实践创新能力培养为研究目标,阐述其实践创新能力培养现状。目前的现状是学校重视课堂教学,忽视实践教学环节;实验室和校外实习基地建设落后;学生创新意识和创新能力严重不足。作者认为,在大学生创新能力培养上,高等农林院校应该大力推广实施创新教育,加强大学生基础教育外延拓展及构建合理的课程体系,积极营造高校创新环境与创新氛围,开设专门的创新课程等。这些都有助于学生实践创新能力的培养。

With the aging of rural population,weakening of traditional family support of old people and function of land guarantee,the problems of rural cares for the aged has become more and more severe.In order to work out the problem of providing elderly with a sense of security,China began to try and popularize new type rural social endowment insurance in 2009.Based on investigation in Hubei province,this paper uses Logistic multiple regression model to analyze the results of the above investigation.Through impact of farmer＇s income,extent of understanding social endowment insurance,way of financing and operating model on farmer＇s willlingness to take part in this insurance,this paper further discusses the main factors and countermeasures which influence the experimental and popularized pension system in rural areas.The result shows that six factors of farmer＇s family income,type of farming,financing options,ways of endowment insurance,land untilization and operating of fund of rural social endowment insurance have significant impact on farmer＇s participation in new type rural pension system,but their impact level is different.

The majority of rural labor in Hubei province transfer to the outside of the province.The inter-provincial transfer showed an imbalance phenomenon,the rural labors in Hubei province mainly transferred to the middle cities in the eastern China.The causes for area distribution of rural labor in Hubei province were analyzed from economics.The results showed that farmers' immigration decision is rational,which accord with maximization of theirs income.The rural labor transfer related to the developmental level of regional economy.The transfer will increase the elasticity of income gap,and the increasing gap of economy and income between provinces will directly influences the move in amount of rural labors.Besides opportunity cost,the rural labor transfer is influenced by living cost in move in area,spatial distance between two places and self-factors of farmers.Therefore,in order to provide more employment opportunities and employment posts for the rural labor transfer in Hubei province,it should comply with the rule of rural labor transfer and developmental situations of local economy,and should pay great attention to constructing small and medium-sized towns and cities,developing the labor-intensive enterprise and the export-oriented enterprise vigorously,strengthening the economic power of Hubei Province.At the meantime,it should conduct innovation in policy and system,establish skill training system,social security system and information transfer system for rural labor,as well as management system for overall planning residents in city and countryside.

Using SAM multiplier theory,this paper examines the identification of leading industries in China under resource constraints,based on 2007 social accounting matrix for China.From the perspective of vertical linkage,this paper examines the impact of the following resource constraints,namely unskilled labor force,skilled labor force and land constraints.The result shows that,compared with the case without resource constraints,revised forward and backward linkages are both reduced under the condition of resource constraints.In other words,the existence of resource constraints weakens the linkages among different sectors.Meanwhile,as the number of constraints increases,the range of leading industries also decreases.Further analysis shows that different types of resource constraints have different impact on vertical linkages of a certain industry.That is to say,the characteristics of resource constraints will also affect the identification of leading industries in China.

The level of technological innovation capacity is not only reflected the country's position of competition in the world economy, but also affects its future-oriented industrial policy. Based on construction of appraising quota system of agricultural bio-industry technological innovation, the paper calculates the scores of agricultural bio-industry technological innovation capability of China, the United States, France, Canada, the United Kingdom and so on. And then, the paper makes overall evaluation of china's technological innovation capability of agricultural bio-industry.