A knowledge-based molecular screen uncovers a broad-spectrum OsSWEET14 resistance allele to bacterial blight from wild rice
A knowledge-based molecular screen uncovers a broad-spectrum OsSWEET14 resistance allele to bacterial blight from wild rice
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DOI：
10.1111/tpj.13042
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发表时间：
2015-11-01
期刊：
影响因子：
7.2
通讯作者：
Szurek, Boris
中科院分区：
文献类型：
--
作者：
Hutin, Mathilde;Sabot, Francois;Szurek, Boris
转录激活因子样(TAL)效应物是一类由III型转录因子传递的转录因子，通过激活寄主易感基因(S)来增强植物病原性黄单胞菌的毒力。TAL效应器通过部分简并的密码识别他们的DNA靶标(S)，TAL效应器中的模块重复序列与宿主启动子中的核苷酸序列结合。虽然这些知识极大地促进了我们识别新的S基因的能力，但它也可以很容易地用于筛选植物基因组中TAL效应靶序列的变异，并预测SICO中功能丧失的候选基因。在原理验证实验中，我们筛选了169份水稻种质资源对白叶枯病的主要感病基因S的启动子OsSWEET14的多态性，该基因编码一种糖转运蛋白，是许多水稻白叶枯病菌菌株的靶标。米饭。我们发现了一个缺失18个碱基的等位基因，与几个已知激活该基因的TAL效应子的结合位点重叠。我们发现这个等位基因，我们称之为Xa41(T)，对一半的Xoo菌株具有抗性，代表了不同的地理来源和遗传谱系，突出了病原体适应OsSWEET14多态的选择压力，反过来，宿主在这个特定的S基因上创造变异性的可能性也是有限的。对整个水稻属的XA41(T)保守性的分析使我们能够假设其在驯化之前和期间的进化史。我们的发现表明，通过依赖TAL效应器的S基因表达缺失的抗性可以在大量寄主植物的基于知识的分子筛选中得到极大的培育。
Transcription activator-like (TAL) effectors are type III-delivered transcription factors that enhance the virulence of plant pathogenic Xanthomonas species through the activation of host susceptibility (S) genes. TAL effectors recognize their DNA target(s) via a partially degenerate code, whereby modular repeats in the TAL effector bind to nucleotide sequences in the host promoter. Although this knowledge has greatly facilitated our power to identify new S genes, it can also be easily used to screen plant genomes for variations in TAL effector target sequences and to predict for loss-of-function gene candidates in silico. In a proof-of-principle experiment, we screened a germplasm of 169 rice accessions for polymorphism in the promoter of the major bacterial blight susceptibility S gene OsSWEET14, which encodes a sugar transporter targeted by numerous strains of Xanthomonas oryzae pv. oryzae. We identified a single allele with a deletion of 18 bp overlapping with the binding sites targeted by several TAL effectors known to activate the gene. We show that this allele, which we call xa41(t), confers resistance against half of the tested Xoo strains, representative of various geographic origins and genetic lineages, highlighting the selective pressure on the pathogen to accommodate OsSWEET14 polymorphism, and reciprocally the apparent limited possibilities for the host to create variability at this particular S gene. Analysis of xa41(t) conservation across the Oryza genus enabled us to hypothesize scenarios as to its evolutionary history, prior to and during domestication. Our findings demonstrate that resistance through TAL effector-dependent loss of S-gene expression can be greatly fostered upon knowledge-based molecular screening of a large collection of host plants.