Variations in type III effector repertoires, pathological phenotypes and host range of Xanthomonas citri pv. citri pathotypes
Variations in type III effector repertoires, pathological phenotypes and host range of Xanthomonas citri pv. citri pathotypes
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DOI：
10.1111/mpp.12019
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发表时间：
2013-06-01
影响因子：
4.9
通讯作者：
Gagnevin, Lionel
中科院分区：
文献类型：
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作者：
Escalon, Aline;Javegny, Stephanie;Gagnevin, Lionel
黄单胞菌在植物病原细菌进化和出现中的潜在作用引起了人们极大的兴趣，但其寄主范围的决定机制至今仍不清楚。柑橘黄单胞菌致病变种Citri（Xci）是一个有趣的宿主专化模型，因为其致病性变体：致病型A菌株感染广泛的芸香科物种，而致病型A*/AW菌株的宿主范围仅限于墨西哥酸橙（Citrus aurantifolia）和alemow（Citrus macrophylla）。基于收集的55株代表Xci全球多样性评估扩增片段长度多态性（AFLP），我们调查了III型效应（T3 Es）的分布与宿主范围。我们检查了Xci中黄色单胞菌的66个T3 Es的存在，并确定了28个效应子的库，其中26个是所有Xci菌株共有的，而两个（xopAG和xopC 1）仅存在于一些A*/AW菌株中。我们发现，xopAG（= avrGf 1）是目前在所有的AW菌株，但也在三个A* 株遗传上远离AW，所有xopAG含有菌株诱导的过敏反应（HR）葡萄柚和甜橙子。xopAD和xopAG的分析表明，柑橘黄化病菌之间存在水平转移。另一种柑橘病原体，以及一些Xci菌株。A菌株遗传多样性较低，诱导相同的表型反应，并具有不可区分的T3 E库。相反，A*/AW菌株表现出更广泛的遗传多样性，其中分支与地理来源和T3 E剧目，但不与致病性，根据T3 E缺失实验。我们的数据概述了在分析宿主专化机制时考虑XciA*/AW菌株异质性的重要性。
The mechanisms determining the host range of Xanthomonas are still undeciphered, despite much interest in their potential roles in the evolution and emergence of plant pathogenic bacteria. Xanthomonas citri pv. citri (Xci) is an interesting model of host specialization because of its pathogenic variants: pathotype A strains infect a wide range of Rutaceous species, whereas pathotype A*/AW strains have a host range restricted to Mexican lime (Citrus aurantifolia) and alemow (Citrus macrophylla). Based on a collection of 55 strains representative of Xci worldwide diversity assessed by amplified fragment length polymorphism (AFLP), we investigated the distribution of type III effectors (T3Es) in relation to host range. We examined the presence of 66 T3Es from xanthomonads in Xci and identified a repertoire of 28 effectors, 26 of which were shared by all Xci strains, whereas two (xopAG and xopC1) were present only in some A*/AW strains. We found that xopAG (=avrGf1) was present in all AW strains, but also in three A* strains genetically distant from AW, and that all xopAG-containing strains induced the hypersensitive response (HR) on grapefruit and sweet orange. The analysis of xopAD and xopAG suggested horizontal transfer between X.citri pv. bilvae, another citrus pathogen, and some Xci strains. A strains were genetically less diverse, induced identical phenotypic responses and possessed indistinguishable T3E repertoires. Conversely, A*/AW strains exhibited a wider genetic diversity in which clades correlated with geographical origin and T3E repertoire, but not with pathogenicity, according to T3E deletion experiments. Our data outline the importance of taking into account the heterogeneity of XciA*/AW strains when analysing the mechanisms of host specialization.