Herbaceous peony (Paeonia lactiflora Pall.) PlDELLA gene negatively regulates dormancy release and plant growth

DELLA protein plays a significant role in plant growth and development. In this study, PlDELLA with the open reading frame of 1866 bp in length was isolated from Paeonia lactiflora. Overexpression of PlDELLA in Arabidopsis thaliana showed that seed germination was significantly repressed as it took 144∼192 h for the OEs to reach 100 % germination and it required only 60 h for the WT. The OEs were also inhibited in bolting time and in plant vegetative growth. When PlDELLA was silenced in peony by virus-induced gene silencing method, peony budbreak occurred earlier by 8∼10 d and the vegetative growth was significantly accelerated compared with the control group. These results collectively indicated that PlDELLA negatively regulated dormancy release and plant growth. During chilling process to release peony endodormancy, PlDELLA expression down-regulated, and the content of both endogenous active GAs and ABA decreased, indicating decreasing of PlDELLA expression under chilling was not caused by the known gibberellin signal transduction pathway. Besides, PlDELLA had no interaction with the four screened PlWRKYs, PlWRKY13, PlWRKY18, PlWRKY40 or PlWRKY50. These findings not only enrich the knowledge of DELLA protein family, but also provide insights into understanding the function of PlDELLA protein in endodormancy release in peony.