Up-regulation of a homeodomain-leucine zipper gene HD-1 contributes to trichome initiation and development in cotton

Plant trichomes originate from epidermal cells.In this work,we demonstrated that a homeodomain-leucine zipper(HD-Zip)gene,Gh_A06G1283(Gh HD-1A),was related to the leaf trichome trait in allotetraploid cotton and could be a candidate gene for the T_1 locus.The ortholog of GhHD-1A in the hairless accession Gossypium barbadense cv.Hai7124 was interrupted by a long terminal repeat(LTR)retrotransposon,while GhHD-1A worked well in the hairy accession Gossypium hirsutum acc.T586.Sequence and phylogenetic analysis showed that GhHD-1A belonged to the HD-Zip IV gene family,which mainly regulated epidermis hair development in plants.Silencing of GhHD-1A and its homoeologs GhHD-1D in allotetraploid T586and Hai7124 could significantly reduce the density of leaf hairs and affect the expression levels of other genes related to leaf trichome formation.Further analysis found that GhHD-1A mainly regulated trichome initiation on the upper epidermal hairs of leaves in cotton,while the up-regulated expression of GhHD-1A in different organs/tissues also altered epidermal trichome development.This study not only helps to unravel the important roles of GhHD-1A in regulating trichome initiation in cotton,but also provides a reference for exploring the different forms of trichome development in plants.

A MADS-box gene is involved in soybean resistance to multiple Soybean mosaic virus strains

Soybean mosaic virus(SMV)is a member of the genus Potyvirus that extensively impairs global soybean production.The full-length coding sequence of the MADS-box transcription factor Gm CAL was cloned from the SMV-resistant soybean cultivar Kefeng 1.SMV-induced expression analysis indicated that Gm CAL responded quickly to SMV-SC8 infection in Kefeng 1 but not in NN1138-2.Gm CAL was expressed at high levels in flowers and pods but at lower levels in leaves.The gene was localized to the nucleus by subcellular localization assay.Virus-induced gene silencing did not increase the accumulation of SMV in Gm CAL-silenced Kefeng 1 plants(with silencing efficiency~80%)after SC8 inoculation.Gm CAL-silencing plants still conferred resistance to SC8 that might be owing to incomplete silencing of genes with lower expression.SMV content decreased significantly in Gm CAL-overexpressing NN1138-2 plants after SMVSC3,SMV-SC7,and SMV-SC8 inoculation in comparison with a vector control,showing that overexpression of Gm CAL conferred broad-spectrum resistance to multiple SMV strains.These results confirm that Gm CAL,a key regulator but not a specific SC8 resistance gene(Rsc8),is a positive regulatory transcription factor involved in soybean resistance to SMV.

Isolation and Functional Characterization of a B3 Transcription Factor Gene <i>FUSCA3</i>Involved in Pre-Harvest Sprouting Resistance in Wheat

Pre-harvest sprouting (PHS) reduces yields and grain quality, resulting in seriously economic losses in wheat. It has been showed that PHS is significantly correlated to seed dormancy levels. FUSCA3 (FUS3) gene is considered to be the key regulator of seed dormancy. However, little information is available about the function of FUS3 gene (TaFUS3) in wheat. In this study, three homologous genes were identified in wheat grain, and their functions were investigated by gene silencing. Three full-length DNA (3477, 3534 and 3501 bp) and cDNA (1015, 1012 and 1015 bp) sequences encoding a B3 transcription factor, designated TaFUS3-3A, TaFUS3-3B and TaFUS3-3D, were first isolated from common wheat. The transcription of three TaFUS3 genes in seed development and germination process was detected. TaFUS3-3B and TaFUS3-3D had similar expression profiles, and high levels of gene transcripts were detected in seeds at 25 DAP (days after pollination) and after 24 h of imbibition. However, the transcription of TaFUS3-3A was not detected. Silencing of TaFUS3 in common wheat spikes resulted in increased seed germination and PHS. Compared with wild-type, the TaFUS3-silenced plants showed increased expression of genes related to GA biosynthesis and ABA metabolism, and decreased expression of genes associated with ABA biosynthesis. Moreover, silencing of TaFUS3 in wheat plants led to a decrease in embryo sensitivity to ABA and changed the expression of genes involved in ABA signal transduction. The results of gene silencing indicated that TaFUS3 plays a positive role in wheat seed dormancy and PHS-resistance, which might be associated with ABA, GA level and signal transduction.

Virus-Induced Gene Silencing in the Culinary Ginger （Zingiber officinale）： An Effective Mechanism for Down-Regulating Gene Expression in Tropical Monocots

Virus-induced gene silencing （VIGS） has been shown to be effective for transient knockdown of gene expression in plants to analyze the effects of specific genes in development and stress-related responses. VlGS is well established for studies of model systems and crops within the Solanaceae, Brassicaceae, Leguminaceae, and Poaceae, but only recently has been applied to plants residing outside these families. Here, we have demonstrated that barley stripe mosaic virus （BSMV） can infect two species within the Zingiberaceae, and that BSMV-VIGS can be applied to specifically down-regulate phytoene desaturase in the culinary ginger Zingiber officinale. These results suggest that extension of BSMV-VlGS to monocots other than cereals has the potential for directed genetic analyses of many important temperate and tropical crop species.

陆地棉NF-YA基因家族的全基因组鉴定与功能分析

【目的】通过对陆地棉NF-YA基因家族进行全基因组鉴定,分析其表达特性,鉴定其中与棉花开花相关的基因。【方法】利用生物信息学方法系统分析了其理化性质、基因结构、共线性、Ka/Ks、顺式作用元件和表达模式,实时荧光定量聚合酶链反应(Polymerase chain reaction,PCR)分析表达特征,采用病毒诱导基因沉默技术验证基因功能。【结果】陆地棉中鉴定到29个NF-YA基因家族成员,分为5个亚组,定位在18条染色体上;全基因组复制和片段复制是GhNF-YA基因家族扩张的主要动力;启动子区含有大量光反应的顺式作用元件。GhNF-YA基因家族基因在茎、叶中高表达;12个GhNF-YA基因在早熟品种鲁棉研19号和晚熟品种鲁棉研37号中均在第三至六叶时期表达量较高,并且大部分基因在品种间表达差异显著。沉默GhNF-YA18基因的鲁棉研37号植株比对照提前11 d现蕾,并且该基因在白化期和现蕾期的表达量均低于未沉默对照棉株。【结论】本研究对陆地棉NF-YA基因家族进行了鉴定和表达分析,为进一步研究棉花开花调控的分子机制奠定了基础。

TaRAR1 is Required for Lr24-Mediated Wheat Leaf Rust Resistance

Virus-induced gene silencing （VIGS） offers a rapid and high throughout technology platform for the analysis of gene function in plants. The barley stripe mosaic virus （BSMV） VIGS system was optimized in studies silencing phytoene desaturase expression in wheat, and demonstrated that infection with BSMV construct carrying a 412 bp fragment of TaRAR1 caused conversion of incompatible to compatible interactions to Lr24-mediated resistance in wheat TcLr24 and cultivar 5R615 harboring Lr24 whereas infection with a control construct had no effect on resistance or susceptibility. RT- PCR analysis showed that BSMV-induced gene silencing could be detected at mRNA levels. These studies indicated that TaRAR1 was a required component for Lr24-mediated race-specific resistance and the BSMV-VIGS was a powerful tool for dissecting the genetic pathways of disease resistance in hexaploid wheat.

TaARPC5 is required for wheat defense signaling in response to infection by the stripe rust fungus

Numerous studies using a combination of confocal microscopic-and pharmacological-based approaches have demonstrated that the actin cytoskeleton dynamically responds to pathogen infection.Here,we observed that phalloidin treatment induced actin nucleation,resulting in enhanced resistance of wheat against the stripe rust pathogen Puccinia striiformis f.sp.tritici(Pst).To define the mechanism underpinning this process,we characterized a family of conserved actin-binding proteins,the actin related protein(ARP)family,which controls actin polymerization.Specifically,we identified and characterized a wheat ARPC gene(Ta ARPC5),which encodes a 136-amino acid protein containing a P16-Arc domain,the smallest subunit of the ARP2/3 complex.Ta ARPC5 m RNA accumulation was induced following the infection of plants with the avirulent Pst strain,and following the elicitation with flagellin(e.g.,flg22)as well.Subcellular localization analysis revealed that Ta ARPC5 is primarily localized to the cortical actin cytoskeleton,and its precise cellular localizations suggest the proximity to processes correlated with the actin-organelle interface.Upon treatment with virulent Pst,Ta ARPC5-knockdown plants exhibited a significant reduction in the expression of PTI-specific m RNAs.Conversely,we observed enhanced induction of reactive oxygen species(ROS)accumulation and a decrease in Ta CAT1 expression following infection with an incompatible Pst isolate.Together with yeast complementation assays,the current study demonstrates a role for Ta ARPC5 in resistance signaling in wheat against Pst infection by regulating the host actin cytoskeleton.

Transcriptomic analysis of wheat reveals possible resistance mechanism mediated by Yr10 to stripe rust

Stripe rust,caused by Puccinia striiformis f.sp.tritici(Pst),is a catastrophic disease that threatens global wheat yield.Yr10 is a race-specific all-stage disease resistance gene in wheat.However,the resistance mechanism of Yr10 is poorly characterized.Therefore,to elucidate the potential molecular mechanism mediated by Yr10,transcriptomic sequencing was performed at 0,18,and 48 h post-inoculation(hpi)of compatible wheat Avocet S(AvS)and incompatible near-isogenic line(NIL)AvS+Yr10 inoculated with Pst race CYR32.Respectively,227,208,and 4050 differentially expressed genes(DEGs)were identified at 0,18,and 48 hpi between incompatible and compatible interaction.The response of Yr10 to stripe rust involved various processes and activities,as indicated by the results of Gene Ontology(GO)enrichment analysis and Kyoto Encyclopedia of Genes and Genomes(KEGG)pathway analysis.Specifically,the response included photosynthesis,defense response to fungus,metabolic processes related to salicylic acid(SA)and jasmonic acid(JA),and activities related to reactive oxygen species(ROS).Ten candidate genes were selected for qRT-PCR verification and the results showed that the transcriptomic data was reliable.Through the functional analysis of candidate genes by the virus-induced gene silencing(VIGS)system,it was found that the gene TaHPPD(4-hydroxyphenylpyruvate dioxygenase)negatively regulated the resistance of wheat to stripe rust by affecting SA signaling,pathogenesis-related(PR)gene expression,and ROS clearance.Our study provides insight into Yr10-mediated resistance in wheat.