Expression profiling of DREB1 and evaluation of vegetation indices in contrasting wheat genotypes exposed to drought stress

DREBs, the Dehydration Responsive Element binding proteins belonging to the superfamily of AP2/ERF plant transcription factors regulate diverse processes of plant development and stress responses. The expression level of DREB1 transcription factor gene was examined under drought in wheat genotypes of Azerbaijani origin differing in drought resistance: two tetraploid wheat (Triticum durum Desf.), cultivars Barakatli 95 (tolerant), Garagylchyg 2 (sensitive) and two hexaploid wheat (Triticum aestivum L.), cultivars Azamatli 95 (less sensitive), Giymatli 2/17 (sensitive), as well as German hexaploid winter wheat cultivar Batis and the synthetic hexaploid wheat accession Syn022L. The seeds were sown in pots in control and drought blocks inside the growth chamber and 12-day-old seedlings were exposed to drought stress. These genotypes were thoroughly phenotyped for variability of vegetation indices like NDVI, SR, OSAVI, ARI1, GM2 and PRI using spectro-radiometer PolyPen RP400 & RP410 under control and drought stress. In tetraploid genotypes and synthetic wheat accession, the vegetation indices were less affected by drought than in hexaploids and the response to stress recovery was faster. Drought sensitive genotypes experienced lower vegetation indices as compared to the tolerant ones. The expression of DREB1 gene was analyzed at 7 days after stress, when the visible stress-related traits were observed. The transcript level was determined by qRT-PCR using the elongation factor 1 alpha (Elf1-alpha) gene as an internal control. There was no genotypic difference in the basal expression of DREB1 under control conditions. Overall, the transcript levels were significantly increased among all genotypes exposed to drought stress. Futher, under drought stress the expression level of DREB1 in tolerant genotypes increased more than in drought sensitive ones. The German wheat cultivar Batis revealed the highest up-regulation of DREB1 under drought stress conditions. These data will help to screen drought stress tolerance at large scale among the diverse wheat gene pool non-invasively using digital phenotyping.