Cassava MeRS40is required for the regulation of plant salt tolerance

Soil salinity affects the expression of serine/arginine-rich (SR) genes and isoforms by alternative splicing, which in turn regulates the adaptation of plants to stress. We previously identified the cassava SCL and SR subfamilies, belonging to the SR protein family, which are extensively involved in responses to abiotic stresses. However, the post-transcriptional regulatory mechanism of cassava RS subfamily in response to salt stress remains to be explored. In the current study, we identified 37 genes of the RS subfamily from 11 plant species and systematically investigated the transcript levels of the RS40and RS31genes under diverse abiotic stress conditions. Subsequently, an analysis of the conserved protein domains revealed that plant RS subfamily genes were likely to preserve their conserved molecular functions and played critical functional roles in responses to abiotic stresses. Importantly, we found that overexpression of MeRS40in Arabidopsisenhanced salt tolerance by maintaining reactive oxygen species homeostasis and up-regulating the salt-responsive genes. However, overexpression of MeRS40gene in cassava reduced salt tolerance due to the depression of its endogenous gene expression by negative autoregulation of its own pre-mRNA. Moreover, the MeRS40 protein interacted with MeU1-70Ks (MeU1-70Ka and MeU1-70Kb) in vivoand vitro, respectively. Therefore, our findings highlight the critical role of cassava SR proteins in responses to salt stress in plants.