GaMYB85 Plays a Role in Drought Tolerance in Transgenic Arabidopsis

MYB transcription factors (TFs) are involved in diverse biological, functional, and structural processes. Previously, very few studies on R2R3 MYB have been conducted in cotton in response to abiotic stresses. Hamama Islam Butt from the Institute of Cotton Research of Chinese Academy of Agricultural Science expressed GaMYB85, a cotton R2R3 MYB TF, in Arabidopsis thaliana to study the function of the TF in the transgenic plants.

Arabidopsis plants overexpressing GaMYB85 exhibited a higher seed germination rate in response to mannitol and salt stresses, and higher drought avoidance efficiency than wild-type plants. These plants also had notably higher levels of free proline and chlorophyll with subsequent lower water loss rates and higher relative water content.

Germination of GaMYB85 transgenics was found to be more sensitive to abscisic acid (ABA). Moreover, when subjected to treatment with different concentrations of ABA, transgenic plants showed reduced stomatal density, with greater stomatal size and lower stomatal opening rates than wild-type plants. Expression of GaMYB85 led to enhanced expression of stress-related marker genes such as RD22, ADH1, RD29A, P5CS, and ABI5.

These results show previously unknown roles of GaMYB85. This study found that it confers good drought, salt, and freezing tolerance, via an ABA-induced pathway. This TF can potentially be used to develop improved abiotic stress tolerance in cotton.

For more information, read the article in BMC Plant Biology.