Thibivilliers Sandra, Joshi Trupti, Campbell Kimberly B, Scheffler Brian, Xu Dong, Cooper Bret, Nguyen Henry T, Stacey Gary
National Center for Soybean Biotechnology, Center for Sustainable Energy, Divisions of Plant Sciences and Biochemistry, University of Missouri, Columbia, MO 65211, USA.
BMC Plant Biol. 2009 Apr 27;9:46. doi: 10.1186/1471-2229-9-46.
Phaseolus vulgaris (common bean) is the second most important legume crop in the world after soybean. Consequently, yield losses due to fungal infection, like Uromyces appendiculatus (bean rust), have strong consequences. Several resistant genes were identified that confer resistance to bean rust infection. However, the downstream genes and mechanisms involved in bean resistance to infection are poorly characterized.
A subtractive bean cDNA library composed of 10,581 unisequences was constructed and enriched in sequences regulated by either bean rust race 41, a virulent strain, or race 49, an avirulent strain on cultivar Early Gallatin carrying the resistance gene Ur-4. The construction of this library allowed the identification of 6,202 new bean ESTs, significantly adding to the available sequences for this plant. Regulation of selected bean genes in response to bean rust infection was confirmed by qRT-PCR. Plant gene expression was similar for both race 41 and 49 during the first 48 hours of the infection process but varied significantly at the later time points (72-96 hours after inoculation) mainly due to the presence of the Avr4 gene in the race 49 leading to a hypersensitive response in the bean plants. A biphasic pattern of gene expression was observed for several genes regulated in response to fungal infection.
The enrichment of the public database with over 6,000 bean ESTs significantly adds to the genomic resources available for this important crop plant. The analysis of these genes in response to bean rust infection provides a foundation for further studies of the mechanism of fungal disease resistance. The expression pattern of 90 bean genes upon rust infection shares several features with other legumes infected by biotrophic fungi. This finding suggests that the P. vulgaris-U. appendiculatus pathosystem could serve as a model to explore legume-rust interaction.
菜豆是世界上仅次于大豆的第二重要豆类作物。因此，由真菌感染（如疣顶单胞锈菌引起的豆锈病）导致的产量损失影响重大。已鉴定出多个赋予抗豆锈病能力的抗性基因。然而，菜豆抗感染的下游基因和机制尚未得到充分表征。
构建了一个由10581个单序列组成的消减菜豆cDNA文库，该文库富含受锈菌41号生理小种（一种致病菌株）或49号生理小种（对携带抗性基因Ur-4的早加拉廷品种无毒的菌株）调控的序列。该文库的构建使得能够鉴定出6202个新的菜豆EST，显著增加了该植物的可用序列。通过qRT-PCR证实了所选菜豆基因对豆锈病感染的响应调控。在感染过程的前48小时内，41号和49号生理小种的植物基因表达相似，但在后期时间点（接种后72 - 96小时）差异显著，这主要是由于49号生理小种中存在Avr4基因，导致菜豆植株出现过敏反应。观察到几个受真菌感染调控的基因呈现双相基因表达模式。
超过6000个菜豆EST丰富了公共数据库，显著增加了这种重要作物的基因组资源。对这些基因对豆锈病感染的响应分析为进一步研究真菌病害抗性机制奠定了基础。90个菜豆基因在锈病感染后的表达模式与其他受活体营养型真菌感染的豆科植物有几个共同特征。这一发现表明菜豆 - 疣顶单胞锈菌病理系统可作为探索豆科植物与锈菌相互作用的模型。
