Accumulation of viroid-specific small RNAs and increase in nucleolytic activities linked to viroid-caused pathogenesis
Accumulation of viroid-specific small RNAs and increase in nucleolytic activities linked to viroid-caused pathogenesis
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DOI：
10.1515/bc.2007.001
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发表时间：
2007-01-01
影响因子：
3.7
通讯作者：
Riesner, Detlev
中科院分区：
文献类型：
--
作者：
Matousek, Jaroslav;Kozlova, Petra;Riesner, Detlev
类病毒引起的致病作用在番茄中得到了很强的证实。通过生物遗传转移严重或致死的马铃薯纺锤体块茎类病毒(PSTVd)菌株，而其他番茄基因型(如MoneyMaker)是耐受的。通过敏感和耐受基因之间的正反交，我们证明了植物逆境支配着耐性。将致病性最强的PSTVd菌株AS1生物转移到无症状的PSTVd宿主本氏烟草上，引起了强烈的致病反应和发育迟缓，表明在该植物中存在特异的类病毒致病促进靶点(S)。与温和的QFA品系相比，AS1生物侵染后，强症状番茄和N.benthamiana植株中小siRNA样PSTVd特异RNA的总水平增加。这表明类病毒特异性小RNA水平的升高与强烈症状的产生有关。在有症状的番茄叶片中，与对照相比，维管系统中约18 kDa的核糖核酸酶被诱导，34 kDa的核酸酶活性提高了7倍。序列分析表明，该核酸酶基因与植物凋亡内切酶有很高的同源性。光镜观察表明，倒伏植物中木质部组织的某些缺失和新维管束的建立受阻，从而支持了维管束的致病作用。
Strong viroid-caused pathogenesis was achieved in tomato cv. Rutgers by biolistic transfer of severe or lethal potato spindle tuber viroid (PSTVd) strains, while other tomato genotypes (e.g., Moneymaker) were tolerant. With reciprocal hybrids between sensitive and tolerant genotypes, we show that plant depression dominates over tolerance. Biolistic transfer of the most pathogenic PSTVd strain AS1 to Nicotiana benthamiana, which is considered to be a symptomless PSTVd host, led to a strong pathogenesis reaction and stunting, suggesting the presence of specific viroid pathogenesis-promoting target(s) in this plant species. Total levels of small siRNA-like PSTVd-specific RNAs were enhanced in strongly symptomatic tomato and N. benthamiana plants after biolistic infection with AS1 in comparison to the mild QFA strain. This indicates association of elevated levels of viroid-specific small RNA with production of strong symptoms. In symptom-bearing tomato leaves in comparison to controls, an RNase of approximately 18 kDa was induced and the activity of a nuclease of 34 kDa was elevated by a factor of seven in the vascular system. Sequence analysis of the nuclease cDNA designated TBN1 showed high homology with plant apoptotic endonucleases. The vascular-specific pathogenesis action is supported by light microscopic observations demonstrating a certain lack of xylem tissue and an arrest of the establishment of new vascular bundles in collapsed plants.