Infiltration with Agrobacterium tumefaciens induces host defense and development-dependent responses in the infiltrated zone.
Infiltration with Agrobacterium tumefaciens induces host defense and development-dependent responses in the infiltrated zone.
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DOI：
10.1094/mpmi-21-12-1528
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发表时间：
2008-11
期刊：
影响因子：
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通讯作者：
G. Pruss;E. Nester;V. Vance
中科院分区：
文献类型：
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作者：
G. Pruss;E. Nester;V. Vance
尽管根癌农杆菌被广泛用于将基因转移到植物系统中，但寄主对这种植物病原菌的反应还不是很清楚。本研究表明，解除武装的农杆菌菌株渗入烟草叶片后，可诱导不同的寄主反应。这些反应局限于渗透区，包括：(1)诱导病程相关(PR)基因PR-1的表达和对随后侵染烟草花叶病毒的抗性；(2)叶绿体失绿和叶绿体rRNAs的丧失；(3)抑制叶片扩张。后两组反应的诱导取决于叶片的年龄，在幼叶中最为明显。有或没有双载体的菌株都能诱导所有的反应，这表明DNA转移既不是必需的，也不是抑制的。经肿瘤诱导(Ti)质粒治愈的根癌农杆菌在诱导这三种反应方面略有缺陷，表明非武装菌株产生的Ti质粒编码因子只起到了很小的作用。然而，T-DNA编码的因子改变了至少一个宿主反应，因为致癌菌株C58的渗透比非武装对照诱导了更明显的黄化。生长素是根癌农杆菌致病相关的T-DNA产物之一。我们发现，C58-渗透区-但不是那些与解除武装的对照渗透的区域-增加了miR393的水平，miR393是一种抑制生长素信号并促进抗菌素耐药性的microRNA。
Despite the widespread use of Agrobacterium tumefaciens to transfer genes into plant systems, host responses to this plant pathogen are not well understood. The present study shows that disarmed strains of Agrobacterium induce distinct host responses when infiltrated into leaves of Nicotiana tabacum. The responses are limited to the infiltrated zone and consist of i) induction of pathogenesis-related (PR) gene PR-1 expression and resistance to subsequent infection with tobacco mosaic virus, ii) chlorosis and loss of chloroplast rRNAs, and iii) inhibition of leaf expansion. Induction of the latter two sets of responses depends on the age of the leaf and is most apparent in young leaves. Strains with or without binary vectors induce all the responses, showing that DNA transfer is neither required nor inhibitory. A. tumefaciens cured of the tumor-inducing (Ti) plasmid is slightly defective for induction of the three responses, showing that Ti plasmid-encoded factors produced by the disarmed strains contribute only slightly. However, T-DNA-encoded factors alter at least one of the host responses, because infiltration with the oncogenic strain C58 induced more pronounced chlorosis than the disarmed control. Auxin is one of the T-DNA products responsible for disease induction by oncogenic A. tumefaciens. We found that C58-infiltrated zones-but not those infiltrated with the disarmed control-have increased levels of miR393, a microRNA that represses auxin signaling and contributes to antibacterial resistance.