vsiRNAs derived from the miRNA-generating sites of pri-tae-miR159a based on the BSMV system play positive roles in the wheat response to Puccinia striiformis f. sp. tritici through the regulation of taMyb3 expression.

Plants live in a complex environment, exposed to stresses, such as unsuitable climates, pests and pathogenic microorganisms. Pathogens are one of the most serious factors that threaten plant growth. Wheat stripe rust, caused by Puccinia striiformis f. sp. tritici (Pst), is one of the most destructive diseases worldwide. Virus-induced gene silencing (VIGS) is a popular tool for the functional analysis of wheat genes, generating abundant small RNAs (sRNAs). sRNAs are key components in gene regulatory networks, silencing corresponding genes at the post-transcriptional level. In this study, we transduced pri-tae-miR159a into plant tissues using the barley stripe mosaic virus (BSMV) system, and demonstrated that vsiRNAs were generated from the same miRNAs generating sites of pri-tae-miR159a, with the function of Dicer RNase III-like classes of endonucleases (DCL4). In addition, the accumulation of vsiRNAs in wheat leaves challenged with Pst Chinese yellow rust 23 (CYR23), resulted in a resistant phenotype, and in the compatible interaction, the sporation of Pst was limited. Whereas, infection with a control construct had no effect on the resistance or susceptibility. The results of the histological observation also supported these phenotype changes. Interestingly, vsiRNAs were also involved in the interactions between wheat and Pst through the tae-miR159-mediated regulation of taMyb3 expression. Moreover, these results also supported the speculation that vsiRNAs were generated from the same sites of pri-tae-miR159a. These studies indicated that vsiRNAs from miRNAs generating sites of pri-tae-miR159a based on the BSMV system play positive roles in the wheat response to Pst through the regulation of taMyb3 expression.