| Summary: | <i>Puccinia striiformis</i> f. sp. <i>tritici</i> is an obligate biotrophic fungus that causes destructive stripe rust disease in wheat. During infection, <i>Pst</i> secretes virulence effectors via a specific infection structure—the haustorium—inside host cells to disturb host immunity and promote fungal colonization and expansion. Hence, the identification and functional analyses of <i>Pst</i> effectors are of great significance in deciphering the <i>Pst</i> pathogenicity mechanism. Here, we identified one candidate <i>Pst</i> effector Pst_9302 that could suppress Bax-triggered cell death in <i>Nicotiana benthamiana</i>. qRT-PCR analyses showed that the transcript levels of <i>Pst_9302</i> were highly increased during the early infection stages of <i>Pst</i>. The transient expression of <i>Pst_9302</i> in wheat via the type-three secretion system (T3SS) significantly inhibited the callose deposition induced by <i>Pseudomonas syringae</i> EtHAn. During wheat–<i>Pst</i> interaction, <i>Pst_9302</i> overexpression suppressed reactive oxygen species (ROS) accumulation and cell death caused by the avirulent <i>Pst</i> race CYR23. The host-induced gene silencing (HIGS) of <i>Pst_9302</i> resulted in decreased <i>Pst</i> pathogenicity with reduced infection area. The results suggest that Pst_9302 plays a virulence role in suppressing plant immunity and promoting <i>Pst</i> pathogenicity. Moreover, wheat voltage-dependent anion channel 1 protein (TaVDAC1) was identified as candidate Pst_9302-interacting proteins by yeast two-hybrid (Y2H) screening. Pull-down assays using the His-Pst_9302 and GST-TaVDAC1 protein verified their interactions. These results suggest that Pst_9302 may modulate wheat TaVDAC1 to regulate plant immunity.
|
|---|