Precise Expression of DREB1A Gene Is Required for Proper Seed Germination, Vegetative and Reproductive Development, and Seed Grain Yield in Arabidopsis thaliana

Life-history traits and biometrics of plant development are greatly influenced by their changing environment. To survive under various stressful environments, plants develop a multifaceted regulatory network that is mainly governed by transcription factors, including the dehydration responsive element binding (DREB) family. The roles of DREB1A have been investigated in responses of plants to various abiotic stresses, however, its effects on plants growth and development over the whole life cycle has not yet been fully described. Here, we studied detailed developmental characterizations of dreb1a T-DNA insertional mutant alongside a previously reported DREB1A overexpressing plants (OX28) in Arabidopsis thaliana. Seed germination, vegetative and reproductive growth stages and plant yield were also investigated. Under normal growth conditions, both dreb1a and OX28 plants exhibited reduced seed germination and delayed early development. In addition, both dreb1a and OX28 plants showed prolonged vegetative growth and delayed transition from vegetative to reproductive development. At the reproductive phase, the time between the emergence of flower stem bolting and opening of the first flower in dreb1a was 15% shorter in comparison to wild type (WTCol0). In contrast, the OX28 plant had a prolonged reproductive development with a remarkably increased number of flowers per plant. Interestingly, lateral branches on the main inflorescence stem showed a lower number in dreb1a, as opposed to the OX28 plant. Despite these observations, in both dreb1a and OX28 plants the total seed weight was decreased significantly. Our findings proposed that there was a relationship between a high expression level of the DREB1A gene with the development and seed yield of A. thaliana.