A wheat NBS-LRR gene TaRGA19 participates in Lr19-mediated resistance to Puccinia triticina

Wheat leaf rust, caused by Puccinia triticina (Pt), is one of the most severe fungal diseases on wheat globally. Rational utilization of wheat leaf rust resistance (Lr) genes is still the best choice for control this disease. Wheat seedlings carrying Lr19 showed a high resistance phenotype to all Pt races in China. So far, all the cloned seedling Lr genes including Lr1, Lr10 and Lr21, encode protein with NBS-LRR domain. In this study, a wheat gene with NBS-LRR domain from previously established Lr19-resistance-related cDNA library was cloned and designated as TaRGA19. Full length of this gene was amplified by rapid amplification of cDNA ends (RACE). By blast against IWGSC wheat genome database, we have noticed that TaRGA19 was located on chromosome 2DS, which was different from Lr19 located on chromosome 7DL. Compared with susceptible Thatcher line, expression level of TaRGA19 was upregulated in wheat isogenic lines carrying Lr19 (TcLr19) after inoculation of Pt race THTS. By particle bombardment, TaRGA19-GFP fused protein was localized on plasma membrane of epidermal cells. Using virus-induced gene silencing (VIGS), TaRGA19-knockdown plants of TcLr19 showed reduced resistance and few sporulation phenotype upon Pt challenge. Further histological observation indicated that Pt hyphal growth at the infection sites was less suppressed in the TaRGA19-knockdown plants. In conclusion, we speculate this TaRGA19 gene was involved in the Lr19-mediated resistance to wheat leaf rust along with other components.