Preliminary Study On The Function Of SlRop1-like And SlRop9 Genes Against Oidium Neolycopersici

Tomato powdery mildew is a worldwide fungal disease,which has been seriously spread and affected tomato yield in recent years.Chemical synthetic pesticides have negative environmental impact and there is the lack of tomato varieties against tomato powdery mildew that easily produces drug resistance.So it is important to screen resistant genes against the disease.Recently,the regulation of Rops genes in disease resistance has attracted more and more attention.In this study,we inoculated O.neolycopersici on resistant and susceptible tomato plants,respectively.Two Rops genes associated with resistance were preliminarily screened by real-time quantitative PCR(RT-qPCR).In addition,the Rops screened were silenced by virus induced gene silence(VIGS)and the function of these Rops was verified by phenotypic and histological observation.The results are as follows:The pathogen strain was identified as O.neolycopersici by morphological observation.We inoculated the pathogen on 20 varieties tomato plants and obtained the high resistant tomato variety Solanum habeochaites LA1777.The histological observation results showed that the formation time of conidium infection structure was delayed in resistant plant,HR and ROS production increased significantly compared with the susceptible plant.The expression of SlRop9 gene significantly up-regulated in resistant plant,peaked and was 10.24 times than that of the control by RT-qPCR.Meanwhile,SlRop1-like expression was significantly down-regulated in susceptible plant.The VIGS results showed that the silencing efficiencies of SlRop9 and SlRop1-like were76% and 50%,respectively.Compared with the control,the time was earlier about conidium germination,appressorium formation and haustorium formation in silenced-SlRop9 plant.Similarly,conidium germination,appressorium formation and haustorium formation rate were higher in silenced-SlRop1-like plant than that of control.In addition,HR and ROS formation rates were decreased in silenced-SlRop9 and silenced-SlRop1-like plants obviously.In conclusion,SlRop9 and SlRop1-like could be related to defense response triggered by O.neolycopersici infection.