Proline Dehydrogenase Gene TaProDH1 Positively Regulates Wheat Resistance to Stripe Rust Disease

Proline dehydrogenase (ProDH) is a rate-limiting enzyme in the proline metabolism cycle that plays an important role in plant stress response and disease resistance. However, the function and mechanism of ProDH1 in the wheat–Puccinia striiformis f. sp. tritici (Pst) interaction remain poorly understood. In this study, a wheat proline dehydrogenase gene TaProDH1 was induced by stripe rust. qRT-PCR analyses showed that the transcript levels of TaProDH1 were highly increased during early infection. The transient expression of TaProDH1 in Nicotiana benthamiana leaves revealed that TaProDH1 increases the content of proline in leaves and induces the accumulation of reactive oxygen species. Silencing TaProDH1 via the barley stripe mosaic virus (BSMV)-induced gene silencing (VIGS) system led to compromised wheat resistance to the Pst avirulent pathotype CYR23, significantly increased proline content in the plant, and increased mycelial growth and sporulation of the pathogen. In addition, it was confirmed by the yeast one-hybrid (Y1H) and dual-luciferase reporter systems that the transcription factor TaMYB30 can activate its transcriptional activity by binding to the TaProDH1 promoter region. In summary, the TaProDH1 gene is a positive regulator of stripe rust resistance in wheat. It is activated by the upstream transcription factor TaMYB30 and accelerates the process of proline metabolism, which is conducive to enhancing the resistance of wheat to stripe rust.