Abiotic Stress Response of Medicago truncatula Plants, Modified with Gain and Loss-of-function of GRAS7 Transcription Factor

Abstract

Abiotic stresses, among which salinity, are substantial limiting factors for crop yield in contemporary agriculture. Abiotic stress response in plants is governed by a plethora of hormonal signalling, which in turn causes a fine-tuning of gene expression, regulated by stress-responsive transcription factors. The GRAS family of transcription factors mediates the gibberellin signalling and plays a major role in growth and development. In the present study, the role of MtGRAS7 transcription factor in abiotic stress response was explored in the model legume Medicago truncatula. Three major biochemical markers, L-proline, malondialdehyde, and hydrogen peroxide, were measured under salinity, drought, and cold temperature stress in MtGRAS7 overexpressing and loss-of-function lines. Under drought and salinity, while not directly related to osmoprotection and antioxidant response, the overexpression of GRAS7 showed a positive effect on the plant stress response, possibly through improved nodulation. The same transcription factor may have a more direct role in response to cold stress, as suggested by our results and literature data.