Dormancy-associated gene 1 (OsDRM1) as a growth repressor: Inhibiting bud outgrowth and plant development, and responsiveness to auxin in rice (Oryza sativa L.)

Dormancy-Associated Genes 1/Auxin-Repressed Proteins (DRM1/ARP) are associated with bud dormancy, repression of plant growth, and responsiveness to hormones. To further explore the function of DRM1 proteins in rice, we isolated a dormancy-associated gene1 (OsDRM1) through microarray analysis. In situ hybridization analyses revealed that OsDRM1 is predominantly expressed in dormant axillary buds, while it is weakly expressed in growing buds, indicating that OsDRM1 gene can be used as a molecular marker for bud dormancy in rice. Overexpression of OsDRM1 in transgenic plants delayed axillary bud outgrowth by suppressing cell division within the buds. Further studies in OsDRM1-overexpressing transgenic plants showed a reduction in plant height, inhibition of root and hypocotyl elongation, and delayed heading time. Under auxin treatment, overexpression of OsDRM1 in transgenic lines partially rescued the shortened length of the primary and crown root. Taken together, these results indicated that OsDRM1 delayed bud growth by arresting the cell cycle and act as a growth repressor affect rice development by modulated auxin signaling.