Functional Study Of StDeSI2 In Potato Late Blight Resistance And Creation Of Its Transgenic Materials

Potato is the world’s fourth largest food crop and the most important non-cereal crop that plays an important role in ensuring world food security.Late blight,caused by the pathogenic Phytophthora infestans,is the most important disease in potato production,seriously affecting potato growth and yield.Molecular disease resistance breeding has proved to be the most cost-effective method,so more potato late blight resistance gene resources need to be explored.In the early stage of this laboratory,Avr8 was used as bait to screen a target protein St De SI2(de SUMOylated proteases)in the potato cultivar Désirée by yeast two hybridization(Y2H),and the interaction was further verified by three protein interaction methods,and study of St De SI2 in potato late blight resistance in its transgenic materials,respectively.The main results are as follows:1.Two potato transgenic lines were obtained by transforming the Avr8 gene of P.infestans into Désirée through Agrobacterium-mediated stem segment transformation,and their late blight resistance was tested by detached leaf assay with inoculating the P.infestans isolate 88069.Results showed that the lesion size was significantly increased,which proved that Avr8 could promote the infection of P.infestans on potatoes.The interaction between Avr8 and St De SI2 was further verified by point-to-point Y2 H,split-luciferase complementation and co-immunoprecipitation assays.And Avr8 can reduce the accumulation of St De SI2 protein through 26 S proteasome.2.Then St De SI2 was transformed into Désirée,and a total of 11 RNAi and 5overexpressing potato transgenic lines were obtained.By detached leaf assay,P.infestans isolates 88069 were inoculated on the leaves of N.benthamiana that silenced or overexpressed De SI2 by Agrobacterium-mediated transient assay,as well as on potato with stable transformation of St De SI2.Compared to non-GMO strains,the lesion size was increased significantly after silencing St De SI2,while was decreased significantly after overexpressing St De SI2.The above results show that De SI2 plays a positive regulatory role in late blight resistance.3.The potato tubers of the RNAi and overexpressing transgenic lines of St De SI2 were measured and counted.Results showed that after silencing St De SI2,the number of tubers did not change significantly compared with the control Désirée,but the weight of tubers decreased significantly.In contrast,there was no significant change in the number and weight of tubers after overexpression of St De SI2.The statistical results of potato count and potato weight proved that St De SI2 did not affect potato yield while improving resistance to late blight,and was suitable for disease-resistant breeding.