ARABIDOPSIS NITRATE REGULATED 1 acts as a negative modulator of seed germination by activating ABI 3 expression

Summary Seed germination is a crucial transition point in plant life and is tightly regulated by environmental conditions through the coordination of two phytohormones, gibberellin and abscisic acid ( ABA ). To avoid unfavorable conditions, plants have evolved safeguard mechanisms for seed germination. The present contribution reports a novel function of the Arabidopsis MCM1/AGAMOUS/DEFICIENS/SRF(MADS)‐box transcription factor ARABIDOPSIS NITRATE REGULATED 1 ( ANR 1) in seed germination. ANR 1 knockout mutant is insensitive to ABA , salt and osmotic stress during the seed germination and early seedling development stages, whereas ANR 1 ‐overexpressing lines are hypersensitive. ANR 1 is responsive to ABA and abiotic stresses and upregulates the expression of ABA Intolerant ( ABI ) 3 to suppress seed germination. ANR 1 and ABI 3 have similar expression pattern during seed germination. Genetically, ABI 3 acts downstream of ANR 1 . Chromatin immunoprecipitation and yeast‐one‐hybrid assays showed that ANR 1 could bind to the ABI 3 promoter to regulate its expression. In addition, ANR 1 acts synergistically with AGL 21 to suppress seed germination in response to ABA as evidenced by anr1 agl21 double mutant. Taken together, the results herein demonstrate that the ANR 1 plays an important role in regulating seed germination and early postgermination growth. ANR 1 and AGL 21 together constitutes a safeguard mechanism for seed germination to avoid unfavorable conditions.