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[科技图书] Plant Breeding and Cultivar Development 进入全文

Elsevier

Plant Breeding and Cultivar Development features an optimal balance between classical and modern tools and techniques related to plant breeding. Written for a global audience and based on the extensive international experience of the authors, the book features pertinent examples from major and minor world crops. Advanced data analytics (machine learning), phenomics and artificial intelligence are explored in the book's 30 chapters that cover classical and modern plant breeding. By presenting these advancements in specific detail, private and public sector breeding programs will learn about new, effective and efficient implementation.          The insights are clear enough that non-plant breeding majoring students will find it useful to learn about the subject, while advanced level students and researchers and practitioners will find practical examples that help them implement their work.

[前沿资讯] 植物免疫机制研究取得进展 进入全文

中国科学院

植物与病原微生物长期协同进化过程中,形成了多层次的防御体系抑制病原的侵染。近日,生物互作卓越中心研究员周俭民团队在植物免疫机制研究中取得新进展。             次生代谢物在植物抵御病原侵染中发挥着重要的作用,目前发现的植物次生代谢物种类繁多、结构各异,但对其作用机制的认识匮乏。对植物抗菌代谢物活性的认知主要基于多数抗菌代谢物在体外具有杀菌或抑菌的活性,但不加选择地杀灭病原微生物和有益微生物显然不利于植物的正常生长。大多数革兰氏阴性病原细菌,比如丁香假单胞菌,利用其分泌系统向宿主细胞内分泌效应蛋白,干扰宿主的生命活动,导致病害。研究团队首次发现十字花科植物特有天然产物SFN能够特异共价修饰调控分泌系统表达的转录因子,从而抑制病原细菌的致病力、增强植物的抗病性。更为重要的是,SFN不影响有益微生物在植物上的定殖(Wang et al., 2020 Cell Host & Microbe)。            植物调动次生代谢物抑制病原细菌效应表达的同时,也利用其胞内免疫受体(主要是NLR蛋白)识别进入到其细胞内部的效应蛋白,激活免疫反应,保护自身免受伤害。前期,研究团队与其他研究团队合作,在体外组装了激活形式的ZAR1复合物(抗病小体),解析了第一个植物NLR抗病蛋白激活前后的结构。然而,在植物体内病原微生物效应蛋白是否能够诱导抗病蛋白复合物的形成还不清楚。抗病蛋白ZAR1能够与一类不具有酶活的蛋白激酶结合,识别多个病原微生物效应蛋白,如AvrAC与HopZ1a。团队首先发现了AvrAC能够在植物细胞内诱导ZAR1形成大约900 kDa分子量的复合物,这与之前报道的体外ZAR1抗病小体分子量相似。进一步研究发现,HopZ1a也同样能够诱导ZAR1在植物细胞内形成寡聚复合物。研究人员结合ZAR1抗病小体的晶体结构,对ZAR1及假激酶ZED1进行位点突变,发现体外组装抗病小体所需的结构位点对HopZ1a诱导ZAR1在植物细胞内寡聚和抗病性是不可缺少的(Hu et al., 2020 Mol Plant)。            该研究工作首次发现植物合成识别敌友的“机智”天然产物,加深了人们对植物抗菌代谢物的认知,同时发现效应蛋白在植物细胞内诱导抗病蛋白寡聚,并证实抗病小体参与不同效应蛋白诱导的植物抗病,对解析植物抗病蛋白激活的分子机制有重要意义。

[前沿资讯] 番茄中的细胞外蛋白水解级联激活免疫蛋白酶Rcr3在植物免疫应答中的作用机制 进入全文

植物生物技术Pbj

木瓜蛋白酶样半胱氨酸蛋白酶(PLCPs)的分泌是整个植物界免疫应答的重要组成部分。PLCPs在免疫中的相关性在植物物种中很明显。例如,柑橘的细菌黄龙病病原体分泌效应子SDE1抑制柑橘类PLCPs,而玉米黑穗病菌可能分泌效应子Pit2抑制玉米PLCPs。因此,大多数质外体植物病原体产生抑制剂来抑制宿主植物分泌的与防御相关的PLCP。Rcr3是番茄的一种分泌的木瓜蛋白酶样半胱氨酸蛋白酶(PLCP),可作为Cf-2抗性蛋白的共受体来检测黄萎病菌分泌的效应子Avr2。Cf-2对Avr2的识别导致局部程序性细胞死亡。Cf-2编码具有细胞外亮氨酸重复序列的受体样蛋白,而Avr2是一种小的分泌的富含半胱氨酸的蛋白。Avr2结合并抑制Rcr3,这种Avr2-Rcr3复合物被Cf-2识别。因此RCR3抵抗病原菌的能力依靠Cf-2,当cf-2突变之后,Rcr3并不能对番茄叶霉病产生抗性。所以Rcr3对番茄抵御病原菌有着至关重要的作用。而且蛋白水解级联调节动物的免疫力和发育,但是尚未报道植物中的这些级联。             近日英国牛津大学在PNAS上发表了题为“Extracellular proteolytic cascade in tomato activates immune protease Rcr3”的论文。该文章报道了番茄的细胞外免疫蛋白酶Rcr3被P69B和其他枯草蛋白酶(SBTs)激活,揭示了调节茄科植物细胞外免疫的蛋白水解级联反应。                    该项研究中作者检测了Rcr3在Avr2感知中的作用是否需要催化活性。基于所描述的PLCPs的pH依赖性自激活机制,假设缺少催化半胱氨酸的Rcr3突变体将无法激活自身。当递送到酸性环境中时,PLCPs的前结构域会展开,并且蛋白酶会通过在前结构域和蛋白酶结构域之间裂解来激活自身。由于认为Avr2通过与底物结合槽相互作用来抑制Rcr3,因此Rcr3前结构域将禁止Avr2与proRcr3结合。因此,催化失活的proRcr3应该不能去除其前结构域,所以并不能与Avr2相互作用以触发HR。但是,作者发现催化失活的Rcr3仍在加工中,能够结合Avr2并触发HR。研究表明,proRcr3由一类被称为枯草杆菌蛋白酶(SBT)的质外生丝氨酸蛋白酶加工而成。此类包括P69B,也称为致病相关7(PR7),一种在番茄的质外体中丰富的免疫相关SBT。有趣的是,P69B和其他SBT受到E.pf的抑制,EPI1是由致病疫霉产生的一种类似SBT抑制剂效应物,表明该病原体可以通过抑制上游蛋白酶来阻止诱导的免疫PLCPs的激活。研究表明茄科植物中多余的蛋白水解级联会激活免疫蛋白酶以提供强大的质外性免疫。             综上:木瓜蛋白酶样半胱氨酸蛋白酶(PLCPs)的分泌是整个植物界免疫应答的重要组成部分。文章中显示免疫蛋白酶Rcr3被分泌的枯草杆菌蛋白酶激活,枯草杆菌蛋白酶是植物中常见的丝氨酸蛋白酶。枯草蛋白酶P69B通过在天冬氨酸在Rcr3前体的自抑制原结构域和蛋白酶结构域之间的连接处裂解后激活proRcr3,从而激活Rcr3。不同亚科的枯草蛋白酶促进了烟草亲缘种中proRcr3的加工,表明这种蛋白水解级联可能在植物中很常见。因此,分泌枯草杆菌蛋白酶抑制剂的病原体可能会间接阻止免疫蛋白酶的激活。

[学术文献] 锌胁迫下甘蓝型油菜发芽期下胚轴长的全基因组关联分析 进入全文

作物学报

锌(Zn)是重要的微量元素之一,但土壤中过量的锌累积会影响植物的生长发育。本研究以不同遗传来源的140份甘蓝型油菜为材料,利用芸薹属60K SNP芯片对锌胁迫下(30 mg L-1)甘蓝型油菜发芽期相对下胚轴长(RHL)进行全基因组关联分析,筛选与甘蓝型油菜发芽期下胚轴长度显著关联的SNP位点及候选基因。群体结构分析表明,供试的140份甘蓝型油菜被分为2个亚群,其中89%材料间亲缘关系小于0.1,说明供试群体材料亲缘关系比较远。GWAS分析共检测到8个与RHL显著关联的SNP位点,单个SNP位点分别可解释22.0%~33.2%的表型变异。转录组分析获得的差异基因GO富集分析结果表明,上调表达基因主要参与氧化还原反应、离子转运、胁迫反应、防御反应和硫化合物转运。综合全基因组关联分析和转录组测序结果,共鉴定到19个与锌胁迫相关的候选基因,包括编码锌指蛋白家族成员(B-box型和ZFP1)、谷胱甘肽转移酶GSTU21、过氧化物酶家族蛋白、ABC和MFS转运蛋白及细胞壁相关激酶蛋白和一些重要的转录因子(BnaA07g27330D、BnaA02g30270D、BnaA07g27840D、BnaA07g31860D和BnaA07g28000),为深入解析油菜锌胁迫分子机理提供了参考。

[学术文献] Genome-wide analysis of glycerol-3-phosphate O-acyltransferase gene family and functional characterization of two cutin group GPATs in Brassica napus 进入全文

Planta

Main conclusion               Genome-wide identification, spatio-temporal expression analysis and functional characterization of selected Brassica napus GPATs highlight their roles in cuticular wax biosynthesis and defense against fungal pathogens.            Abstract             Glycerol-3-phosphate 1-O-acyltransferase (GPAT) is a key enzyme in the biosynthesis of glycerolipids, a major component of cellular membranes and extracellular protective layers, such as cuticles in plants. Brassica napus is an economically important crop and cultivated worldwide mostly for its edible oil. The B. napus GPATs (BnGPATs) are insufficiently characterized. Here, we performed genome-wide analysis to identify putative GPATs in B. napus and its diploid progenitors B. rapa and B oleracea. The 32 B. napus BnGPATs are phylogenetically divided into three major groups, cutin, suberin, and diverse ancient groups. Analysis of transcriptomes of different tissues and seeds at different developmental stages revealed the spatial and temporal expression profiles of BnGPATs. The yield and oil quality of B. napus are adversely affected by the necrotrophic fungus, Sclerotinia sclerotiorum. We showed that several BnGPATs, including cutin-related BnGPAT19 and 21, were upregulated in the S. sclerotiorum resistant line. RNAi-mediated suppression of BnGPAT19 and 21 in B. napus resulted in thinner cuticle, leading to rapid water and chlorophyll loss in toluidine blue staining and leaf bleaching assays. In addition, the RNAi plants also developed severe necrotic lesions following fungal inoculation compared to the wild-type plants, indicating that BnGPAT19 and 21 are likely involved in cuticular wax biosynthesis that is critical for initial pathogen defense. Taken together, we provided a comprehensive account of GPATs B. napus and characterized BnGPAT19 and 21 for their potential roles in cuticular wax biosynthesis and defense against fungal pathogens.

[学术文献] Genome-wide identification and expression analysis of anthocyanin biosynthetic genes in Brassica juncea 进入全文

Journal of Integrative Agriculture

Anthocyanins confer the wide range of colors for plants and also play beneficial health roles as potentially protective factors against heart disease and cancer. Brassica juncea is cultivated as an edible oil resource and vegetable crop worldwide, thus elucidating the anthocyanin biosynthetic pathway would be helpful to improve the nutritional quality of Brassica juncea through the breeding and cultivating of high anthocyanin content varieties. Herein, 129 genes in B. juncea were identified as orthologs of 41 anthocyanin biosynthetic genes (ABGs) in Arabidopsis thaliana by comparative genomic analyses. The B. juncea ABGs have expanded by whole genome triplication and subsequent allopolyploidizatoin, but lost mainly during the whole genome triplication between B. rapa/B. nigra and A. thaliana, rather than the allopolyploidization process between B. juncea and B. rapa/B. nigra, leading to different copy numbers retention of A. thaliana homologous genes. Although the overall expansion levels ABGs were similar to the whole genome, more negative regulatory genes were retained in the anthocyanin biosynthesis regulatory system. Transcriptional analysis of B. juncea with different anthocyanin accumulation showed that BjDFR, BjTT19, BjTT8 are significantly up-regulated in plants with purple leaves as compared with green leaves. The overexpression of BjTT8 and these target genes which were involved in late anthocyanin biosynthesis and transport might account for increasing levels of anthocyanin accumulation in purple leaves. Our results could promote the understanding of the genetic mechanism of anthocyanin biosynthesis in B. juncea.

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