Two Type III Secretion System Effectors from Ralstonia solanacearum GMI1000 Determine Host-Range Specificity on Tobacco
Two Type III Secretion System Effectors from Ralstonia solanacearum GMI1000 Determine Host-Range Specificity on Tobacco
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DOI：
10.1094/mpmi-22-5-0538
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发表时间：
2009-05-01
影响因子：
3.5
通讯作者：
Genin, Stephane
中科院分区：
文献类型：
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作者：
Poueymiro, Marie;Cunnac, Sebastien;Genin, Stephane
模式病原体青枯菌（Ralstonia solanacearum）GMI 1000是细菌性枯萎病的病原体，该细菌性枯萎病攻击许多茄科植物和其它宿主，但不攻击烟草（Nicotianaspp.）。我们发现两个III型分泌系统效应基因avrA和popP 1限制了菌株GMI 1000在至少三种烟草物种（N.烟草N. benthamiana和N.（图1）这两种效应引起过敏反应（HR）对这些烟草品种，虽然在不同的方式; AvrA是由N的主要决定因素。烟草N. benthamiana，而PopP 1似乎是N上的主要HR激发子。你好只有avrA和popP 1基因的双重失活才允许GMI 1000使烟草植物枯萎，从而表明GMI 1000内在地具有使烟草植物枯萎所必需的功能。对AvrA的集中分析表明，前58个N-末端氨基酸足以将其注射到植物细胞中。我们确定了一个高变区inavrA，其中包含可变数目的串联重复序列（VNTR），每个由12个碱基对组成。我们表明，一个18个氨基酸的区域中发生的VNTR插入是一个重要的域参与HR诱导对N。avrA似乎是各种DNA插入或移动的元件的靶标，这些元件可能允许R.茄科植物逃避烟草的识别和防御反应。
The model pathogenRalstonia solanacearumGMI1000 is the causal agent of the bacterial wilt disease that attacks many solanaceous plants and other hosts but not tobacco (Nicotianaspp.). We found that two type III secretion system effector genes,avrAandpopP1, are limiting the host range of strain GMI1000 on at least three tobacco species (N. tabacum, N. benthamiana, andN. glutinosa). Both effectors elicit the hypersensitive response (HR) on these tobacco species, although in different manners; AvrA is the major determinant recognized byN. tabacumandN. benthamiana, while PopP1 appears to be the major HR elicitor onN. glutinosa. Only the double inactivation of theavrAandpopP1genes allowed GMI1000 to wilt tobacco plants, thus showing that GMI1000 intrinsically possesses the functions necessary to wilt tobacco plants. A focused analysis on AvrA revealed that the first 58 N-terminal amino acids are sufficient to direct its injection into plant cells. We identified a hypervariable region inavrA, which contains variable numbers of tandem repeats (VNTR), each composed of 12 base pairs. We show that an 18–amino acid region in which the VNTR insertion occurs is an important domain involved in HR elicitation onN. benthamiana.avrAappears to be the target of various DNA insertions or mobile elements that probably allowR. solanacearumto evade the recognition and defense responses of tobacco.