Identification, characterization and expression analysis of ERF transcription factor VviERF073 and standardization of stable reference genes under salt stress in grape

Abstract

Salinity is one of the several abiotic factors affecting grape productivity and quality. Transcription factors belonging to AP2/ERF family play an important role in abiotic stress response. Based on the in silico analysis of salt stress libraries of grape ESTs, a transcription factor VviERF073, having a single AP2/ERF conserved domain was identified. The sequence of VviERF073 was analyzed in 'Thompson Seedless'. VviERF073 belonged to the B2 subfamily of ERF transcription factors. Under salt stress, the relative expression of VviERF073 increased 2.7 fold in the leaves of grafted grapevine within six hours of salt stress. The expression increased to 8.7 fold at 15 days of salt stress, thus indicating its role in early as well as late response to salt stress. However, expression of VviERF073 did not change significantly in grapevines raised on own roots. The expression varied in the roots of 'Thompson Seedless' but not in the roots of '110R'. Under salt stress conditions, GAPDH and EF1α for grafted vines and Actin and Tubulin for own root vines, were identified as the stable reference genes for qPCR data normalization.