野生种番茄S. pennellii和S. habrochaites抗列当机制的比较分析

Broomrapes (Orobanche and Phelipanche spp.) are destructive and globle holoroot parasites attacking many economic crops. Among these species, O. aegyptiaca Pers has caused a great limitation for the sustainable development of processing tomato production in China. Strigolactones as a noval phytohormones play an important role in several aspects inculuding the development, the interaction with the holoroot parasites, biotic and abiotic stresses. However, very limited information about its biosynthesis and singling pathway has been known. To illustrate the above issues, two introgression line (IL) populations repectively derived from wild species S. pennellii LA0716 and S. habrochaites LA1777, which showed the diferent extent resistance to O. aegyptiaca Pers, were employed in this project to firstly locate the resistance loci and to uncover their genetic mechanism. Based on the idenfied ILs, the regulation of SL pathway will be analyzed in roots together with their parental lines after the analysis of the gene expression, carotenes and strigolactons in the roots. In addition, tomato mutants will be conducted to further understand the singling pathway mediated by JA and SA for the resistance to broomrapes. The obtained results in this project would be not only directly used for the tomato breeding resistance to O. aegyptiaca Pers, but also for providing the further scientific proof of SL biosynthesis,singling pathway and the interaction with broomrapes.

列当(Orobanche 和Phelipanche spp.)是世界性寄生杂草，其中瓜列当（O. aegyptiaca Pers）已严重阻碍了我国加工番茄产业的可持续发展。独脚金内酯（Strigolactones,SL）作为一种调控植物生长发育、寄生杂草互作、生物与非生物胁迫的重要新型激素，是近年研究的热点，但其代谢合成尚不十分清楚，信号传导途径更不明确。 针对上述问题，项目拟利用对瓜列当不同抗性的野生种番茄S. pennellii LA0716和S. habrochaites LA1777的两个渐渗系群体，将抗列当基因/QTL快速准确定位，揭示其抗性遗传机制；分析基因表达、根际类胡萝卜素和SL类似物组分，阐明番茄SL合成代谢；结合突变体，明确JA和SA是否介导SL信号传导途径。结果不仅可直接用于番茄抗列当新品种选育，而且为阐明SL合成调控、信号传导途径及与列当互作提供必要科学依据。

通过对92份（S. pennellii、S. habrochaites、S. pimpinellifolium PI365967、S.arcanum、S.corneliomulleri、S.chemielewskii、S.peruvianum、S.minutum和41份S. Chilense）资源2年接种列当，调查列当数、出土列当数、列当分枝数和列当鲜重等指标，发现20个野生品种（LA0716、PI365967、W0138、W0142、W0155、W0156、W0161、W0165、W0168、W0174、W0180、W0183、W0190、W0198、W0680、W0686、W0687、W0688、W0689、W0691）表现不同程度耐列当。利用来自耐列当的S. pennellii LA0716、S. habrochaites LA1777及其渐渗系群体，分析耐列当的位点，结果证明S. pennellii LA0716的14 个渐渗系ILs（1-2、2-2、2-3、4-1、4-3、6-2、6-3、7-4、8-1、8-2、9-1、9-2、10-1、10-3）与遗传背景M82 抗列当性差异达到显著或极显著水平，说明LA0716对列当的抗性由数量性状控制，该些渐渗系包含耐裂当的位点；进一步利用亚渐渗系群体对耐裂当的IL6-2进行精细定位，发现IL6-2-10渐渗片段耐裂当。S. habrochaites LA1777的2个渐渗系（LA3928、LA3933）连续2年表现耐列当。细胞学研究表明，LA0716与列当互作，在列当侵染过程中，寄主内皮层增厚阻碍列当的入侵。结合乙烯、水杨酸、茉莉酸激素突变体和番茄红素突变体及基因表达分析结果，表明水杨酸和茉莉酸介导番茄对列当的耐性；番茄红素合成代谢途径也参与番茄耐列当，而且hp较ogc更为明显。