PagWRKY11 regulates leaf morphology and salt sensitivity in Populus alba×P.glandulosa.

WRKY transcription factors (TFs) are key regulators of plant tissue morphogenesis, defense responses, and metabolic regulation. However, the functions for most of WRKY TFs in 84K poplar (Populus alba × P. glandulosa) in regulating leaf morphology and responding to salt stress are remain unclear. In this study, overexpressing PagWRKY11 poplars were generated. Phenotypic analysis revealed that transgenic poplar leaves were narrower and smoother compared to the traditionally elliptical and relatively rough leaves of wild-type (WT) plants. Then, the apical buds of transgenic poplars were sharp and elongated, with young leaves pointing upwards and inwards, whereas WT buds were rounder with smoother young leaves pointing downwards. Functional analysis indicated that under salt stress, the activities of SOD and POD enzymes and the expression of their encoding genes were significantly lower in transgenic poplars compared to WT. Conversely, the accumulation of HO and MDA was significantly higher. These results suggest that overexpression lines of PagWRKY11 increase salt sensitivity by downregulating the expression of antioxidant enzyme genes. Meanwhile, overexpression of PagWRKY11 increased the natural water loss rate of poplar leaves, and negatively regulated salt stress by affecting water retention. In addition, yeast one-hybrid assays showed that PagWRKY11 binds specifically to W-box elements. These results provide a theoretical basis for further exploration of the molecular mechanisms by which PagWRKY11 regulates leaf morphogenesis and stress responses, and offer new potential strategies for resistance breeding.