Exogenous application of luteolin enhances wheat resistance to Puccinia striiformis f. sp. tritici.

The accumulation of flavonoids facilitates plant resistance to biotic stress. However, few studies have explored the functions of flavonoids during the interaction between wheat and Puccinia striiformis Westendorp f. sp. tritici Eriksson (Pst). This study analyzed the expression profiles of flavonoids and their biosynthesis genes in the resistant accession Y0337 and the susceptible accession Y0402 infected with Pst. The results showed that flavonoid biosynthesis pathway (FBP) genes were induced during early Pst infection. Among these, 29 initial FBP DEGs exhibited higher expression during incompatible interaction. Further, the total levels of 12 identified flavonoids were higher during incompatible interaction; among these, apigenin, luteolin, cynaroside were accumulated and naringenin was decreased, they may play a crucial role in Pst resistance. Integrated analysis of the transcriptome and metabolome showed that 21 DEGs regulated four crucial flavonoids biosynthesis. The gene regulatory network suggested that the transcription factors EFRs, WRKYs, NACs, and bHLHs potentially regulated four flavonoids biosynthesis. Additionally, it was shown that luteolin inhibited spore germination and infection of Pstin vivo and in vitro. In summary, these results enhance our understanding of the flavonoids biosynthesis in wheat resistance to Pst and highlight the role of luteolin in this process.