TaMYB29: A Novel R2R3-MYB Transcription Factor Involved in Wheat Defense Against Stripe Rust

Abstract

Members of the R2R3-MYB transcription factor superfamily have been implicated in plant development, improved disease resistance, and defense responses to several types of stresses. To study the function of TaMYB29 transcription factor-a member of the R2R3-MYB superfamily-in response to an avirulent race of stripe rust pathogen, <i>Puccinia striiformis</i> f. sp. <i>tritici</i> (<i>Pst</i>), we identified and cloned the <i>TaMYB29</i> gene from wheat cultivar (cv.) AvS+<i>Yr10</i> following infection with <i>Pst</i>. The TaMYB29 protein, comprising 261 amino acids, contains two highly conserved MYB domains. We first showed that TaMYB29 is a transcription factor, whose transcriptional levels are significantly induced by salicylic acid (SA), abscisic acid (ABA), jasmonic acid (JA), ethylene (ET), and <i>Pst</i>. The results showed that TaMYB29 is involved in the wheat response to stipe rust. The overexpression of the <i>TaMYB29</i> gene resulted in the accumulation of reactive oxygen species (ROS) and pathogen-independent cell death in <i>Nicotiana benthamiana</i> leaves. The silencing of <i>TaMYB29</i> gene in wheat cv. AvS+<i>Yr10</i>, containing the stripe rust resistance gene <i>Yr10</i>, promoted hyphae growth, significantly downregulated the expression of pathogenesis-related (<i>PR</i>) genes, and substantially reduced the wheat resistance to <i>Pst</i> compared with the non-silenced control. In addition, the accumulation of hydrogen peroxide (H₂O₂) significantly decreased, and the activity of catalase, an enzyme required for H₂O₂ scavenging, was elevated. Altogether, TaMYB29 positively regulates the defense response against stripe rust in wheat AvS+<i>Yr10</i> by enhancing H₂O₂ accumulation, <i>PR</i> gene expression, and SA signaling pathway-induced cell death. These results provide new insights into the contribution of TaMYB29 to the defense response against rust pathogens in wheat.