Role of microRNA319 in creeping bentgrass salinity and drought stress response

The microRNA319 family (miR319) is one of the most conserved and ancient microRNA (miRNA) families in plants. Transgenic creeping bentgrass (Agrostis stolonifera) overexpressing a rice miR319, Osa-miR319a, exhibited enhanced salt and drought tolerance. A comprehensive hypothetical model about the role of miR319 in creeping bentgrass response to salinity and drought stress was proposed. Salinity and drought stress induces elevated expression of miR319, resulting in downregulation of at least 4 putative target genes of miR319 (AsPCF5, AsPCF6, AsPCF8, and AsTCP14) as well as a homolog of the rice NAC domain gene AsNAC60, and therefore positively contributing to plant abiotic stress response. Hormones might also regulate miR319 and its targets, and the expression level of the miR319 targets might be a balance of miR319-mediated target cleavage and hormone regulation of the targets. Furthermore, HKT gene families involved in salt exclusion mechanisms as well as mechanisms controlling the timing of gene expression network are also hypothesized to play an important role in this pathway.