Expression of the sesame MYB transcription factor SiMYB305 boosts tolerance to drought and salt stress in Arabidopsis

Improving crop tolerance to environmental stresses is of paramount importance to global food security. To protect themselves from abiotic stress, plants translate environmental inputs into internal signals through hormones, such as abscisic acid (ABA), which in turn activate transcription factors at the genetic level. MYBs are a vital gene family with a large number of members which modulate various biological processes in plants including shoot growth and root formation. They have also attracted attention in various plant species for their involvement in plant abiotic stress tolerance. However, MYBs have yet to be fully investigated in sesame, an important oil crop grown largely in areas highly susceptible to drought and salt stress.

In a recent study published in AoBP, Dossa et al. investigate the function of the sesame SiMYB75 gene in mediating drought and salinity stress. The gene was cloned from sesame (Sesamum indicum L.) and was found to be strongly induced by the presence of drought, sodium chloride (NaCl), abscisic acid (ABA) and mannitol. SiMYB75 was expressed preferentially in roots. Ectopic over-expression of the gene in Arabidopsis thaliana demonstrated that it promotes root growth. SiMYB75’s involvement in drought and salinity tolerance is via the modulation of ABA related gene expression and the inhibition of reactive oxygen species production. The authors conclude that SiMYB75 is a promising candidate gene for the improvement of abiotic stress tolerance in sesame and other crop species. They hope that future work will identify natural variation in SiMYB75 expression across sesame genotypes that could be harnessed through molecular marker assisted plant breeding.