An uncanonical transcription factor-DREB2B regulates seed vigor negatively through ABA pathway

Seed vigor is an important trait for ecology, agronomy, and economy and varies with different plant species and environmental conditions. Dehydration-Responsive Element-Binding Protein 2B (DREB2B), a subgroup of the DREB transcription factor family, is well-known in drought resistance. However, the role of DREB2B in the regulation of seed vigor has not been identified. Here, we found that DREB2B is a negative regulator of seed vigor by ABA-mediated pathway in Arabidopsis with loss of function mutant and over-expressed transgenic lines. Furthermore, DREB2B showed epistatic and parallel to ABI3 simultaneously in seed vigor regulation by genetic and molecular approaches. DREB2B homolog gene (GhDREB2B-A09) was also identified in cotton. The expression analysis indicated that transcripts of DREB2B were higher in mature dry seed, and the transgenic plants showed the conservative roles of DREB2B in Arabidopsis and cotton. In addition, we identified that DREB2B interacted with RADICAL-INDUCED CELL DEATH1 (RCD1) to involve seed vigor regulation together in Arabidopsis and cotton with BiFC experiment and mutant phenotypic analysis. Collectively it is concluded that DREB2B interacting with RCD1 or SRO1 function at upstream of and synergistic with ABI3 to regulate seed vigor negatively in Arabidopsis and cotton, which provides novel knowledge in the seed development study. HighlightsDREB2B transcription is seed specific and a negative regulator of seed vigor by ABA-mediated pathway, which interacts with RCD1s, and functions synergistically with ABI3 to affecet seed germination and vigor in Arabidopsis and cotton.