Transfer Of Potato Late Blight Resistance Gene RB Into Tomato And Analysis Of Signal Transduction

Late blight, caused by the oomycete Phytophthora infestans(Mont.)de Bary, is a devastating disease of two Solanaceous crops, tomato and potato. Now five R genes have been cloned from potato, such as R1, R3a, RB (Rpi-blb1), Rpi-blb2 and Rpi-blb3. RB from the two wild potato species Solanum bulbocastnum is known for its broad spectrum resistance to late blight. The cloned RB gene provides an important resource to develop late blight-resistance Solanaceous plant. Four tomato late blight resistance genes have been mapped, but their effectiveness is limited because of the fast evolving P. infestans pathogen in the field. RB from potato and Avrblb1 from P. infestans are a pair of R-AVR genes which have been cloned in potato and P. infestans which is the basic theory of our research. The results were as follows:1. In order to research that the potato resistance gene RB valid in tomato, the primary transformants of cultivar Moneymaker harboring the RB gene construct were generated. Then transgenic tomato plants were showed resistance to potato-derived isolates 89148-9 and tomato-derived prevalent isoletes and high virulence isolates. It suggests potato late bight gene RB can be used for the tomato late blight breeding and innovate gerplasm of tomato late blight resistance.2. We construct a marker-free vector of RB gene in order to apply with RB in the tomato late blight breeding and production. RB gene was integrated to marker-free vector pBINMF and transient expressed with Avrblb1 in the leave of N. benthamiana.The results showed that HR was induced in the leaves which suggesting that RB was transcripted and translated. The marker-free vector pBINMF: RB will be used in tomato lat blight resistance breeding which offered a new way for tomato late blight trangene breeding.3. R gene mediated resistance requires multiple signal transduction pathways. Virus-induced gene silencing (VIGS) is a powerful tool for studying genes participation in signal pathways. Eight genes, SIPK, NDR1, SGT1, HSP90, NPR1, Rar1, EDS1 and WRKY1 from other species are known to be involved in defence-related signal pathway. Suppressed expression of these genes by VIGS in Nicotiana benthamiana and the results were determined on HR symptoms induced by RB-Avrblb1. RB-mediated resistance was compromised by the silencing of HSP90 and SGT1, suggesting that the RB-Avrblb1 interaction is dependent on ubiquitin ligase-associated protein SGT1 and heat-shock protein HSP90.