Analysis Of Disease-resistance Pathway Of The Receptor Like Kinase StLRPK1

Potato( Solanum tuberosum L.) is the fourth most important cultivated crop worldwide. Late blight, caused by oomycete pathogen Phytophthora infestans, is the devastating disease of potato. The outbreak of this disease led to large scale production lost. St LRPK1, which was cloned by our lab in the previous research, was identified as a leucine rich repeat receptor like protein kinas. Transgenic and resistance analysis indicated that it play an important role in broad-spectrum in late blight resistant. In this study, Nicotiana benthamina and transgenic lines which constitutively over expression St LRPK1, transgenic lines of potato cultivar ‘E3’ were used as the materials to explore the resistance mechanism of St LRPK1 through the late blight resistance test, VIGS analysis, gene expression analysis and transcriptome sequencing analysis. The main results as follow:1. Homozygous N. benthamiana lines that constitutively expression St LRPK1 were selected with the method of Kanamycin resistance screening. P. infestans inoculation with isolate 88069 showed that the resistance level of transgenic lines was significantly improved.2. Gene expression analysis showed that the PTI marker genes were up-regulated in N.benthamiana transgenic lines. These genes also up regulated 24 h after treat with88069, but obvious increase was found in the transgenic lines. This indicate that St LRPK1 increase the P. infestans resistance through PTI.3. Transient expression the fusion protein St LRPK1-GFP showed that the St LRPK1 was located at plasmembrane.4. Use the kinase domain of St LRPK1 as the bait, we didn’t get anything in the Y2 H screen, and no interaction was detected in the specific interaction test between St LRPK1 and St BAK1.5. Nb SIPK and Nb WIPK were silenced in both wide type and transgenic N.benthamiana lines separately. When silenced Nb SIPK, same decrease level of P.infestans resistance was detected in both wide type and transgenic lines. But bigger decrease was detected in transgenic lines when silenced the Nb WIPK. This indicates that the Nb SIPK involved in the St LRPK1 signalling pathway, but Nb SIPK may not.6. Many protein kinases were constitutively down regulated in potato St LRPK1 RNA interference line compare to potato cultivar E3. Many kinases and a number of transcript factors were down regulated 24 h after P. infestanse inoculation. This indicated that St LRPK1 may regulate the resistance through multi kinases signal pathway.