| Résumé | Seed development ends with a maturation phase that imparts desiccation tolerance, nutrient reserves, and dormancy degree. Here we report the functional analysis of an Arabidopsis C2H2 zinc finger protein ENHYDROUS (ENY). Ectopic expression of ENY (2x35S::ENY) disrupted seed development, delaying endosperm depletion and testa senescence, resulting in an abbreviated maturation program. Consequently, mature 2x35S::ENY seeds had increased endosperm-specific fatty acids, starch retention, and defective mucilage extrusion. Using RAB18 promoter ENY lines (RAB18::ENY) to confine expression to maturation when native ENY expression increased and peaked, resulted in mature seed with lower ABA content and decreased germination sensitivity to applied ABA. Further, results of far-red and red light treatments of 2x35S::ENY and RAB18::ENY germinating seeds, and in artificial microRNA knockdown lines, suggest that ENY acts to promote germination. After using RAB18::ENY seedlings to induce ENY during ABA application, key genes in gibberellin (GA) metabolism and signaling were differentially regulated in a manner suggesting negative feedback regulation. Furthermore, GA treatment resulted in a skotomorphogenic-like phenotype in light-grown 2x35S::ENY and RAB18::ENY seedlings. The physical interaction of ENY with DELLAs and an ENY-triggered accumulation of DELLA transcripts during maturation support the conclusion that ENY mediates GA effects to balance ABA-promoted maturation during late seed development. |
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