DISSERTATION RESEARCH: The Evolution of Disease Resistance in the genus Lycopersicon

植物抗病基因编码的受体能够识别不同的病原体并发出防御反应信号。宿主和病原体之间的相互作用引发的防御反应限制了病原体在整个植物中的传播。番茄对紫丁香假单胞菌（pseudomonas syringae pv tomato）的抗病基础在分子水平上得到了广泛的研究，这种番茄是可食用番茄（L. esculentum）的近亲，这些物种之间的育种可以将抗病引入作物物种中。抗性是由Pto基因赋予的，该基因编码一种受体，并发出对这种细菌病原体的防御反应信号。本研究的目的是确定其他番茄品种是否对这种病原体具有抗性，以及抗性是由Pio基因赋予的，还是由这些物种内的其他基因赋予的。Pto基因的功能分析已经确定了该基因参与病原体识别和抗性反应信号传导的区域。这些数据将为分析来自抗性和易感宿主的Pro基因的自然变异提供基础。本研究将调查由Pio基因赋予的抗病性的分类宽度，并确定该基因的氨基酸序列差异如何影响这些物种的抗病性。

Plant disease resistance genes encode receptors which are capable of recognizing different pathogens and signaling defense responses. A defense response triggered by the interaction between a host and pathogen limits the pathogen spread throughout the plant. The basis of disease resistance to the bacterial pathogen, Pseadomonas syringae pv tomato, has been extensively characterized at the molecular level within the host species of Lycopersicon pimpinellifolium This species is a close relative Of the edible tomato, L. esculentum, and breeding between these species has permitted the introduction of disease resistance into the crop species. Resistance is conferred by the Pto gene which encodes a receptor and signals a defense response to this bacterial pathogen. The purpose of this study is to determine whether other species of Lycopersicon are resistant to this pathogen and if resistance is conferred by the Pio gene or by different genes within these species. Functional analysis of the Pto gene has identified the regions of the gene involved in pathogen recognition and signaling of the resistance response. These data will provide a basis for analyzing natural variation in Pro genes -from both resistant and susceptible hosts. This study will investigate the taxonomic breadth of disease resistance conferred by the Pio gene and also identify how amino acid sequence differences in this gene influence disease resistance in these species.