Overexpression of a novel F-box protein PsFFL1 from tree peony ( Paeonia suffruticosa ) confers drought tolerance in tobacco

Tree peony ( Paeonia suffruticosa ) is an important and famous horticultural plant with ornamental, edible, and medicinal values. Drought is one of the main environmental stresses that affects various processes such as plant growth and productivity. The mechanism of drought tolerance has been studied in some plants and crops but not in tree peony. In this study, we identified an F-box protein in tree peony; the protein was named as PsFFL1 (Ps F -box/ F BD/ L RR-repeat) based on the analysis of conserved domains, homologous sequence alignment and structure. Ectopic overexpression of PsFFL1 in tobacco plants demonstrated increased vigorous growth and drought tolerance, and it was significantly up-regulated under drought stress using quantitative RT-PCR (RT-qPCR) analysis. While, PsFFL1 was significantly down-regulated by exogenous naphthylacetic acid and gibberellin acid 3 treatment. Further, under normal or drought conditions, some drought stress-related genes including Late Embryogenesis Abundant5 ( LEA5 ), no apical meristem ( N AM ), Arabidopsis transcription activation factor ( A TAF ), cup-shaped cotyledon 2 ( C UC2 ) ( NAC ), Early Responsive to Dehydration 10 C ( ERD10C ), Calcium-Dependent Protein Kinase2 ( CDPK2 ), WRKY28 and Osmotin were upregulated in the transgenic tobacco lines. Moreover, we preliminarily identified some drought-associated proteins such as Cu/Zn-superoxide dismutase (Cu/Zn-SOD), alcohol dehydrogenases 3 (ADH3), and heat shock proteins (HSPs), which could interact with PsFFL1 as revealed by pull down-mass spectrometry (MS). These results indicated that PsFFL1 plays a positive regulatory role in drought stress response in tree peony. The functions of most of the F-box proteins are not elucidated to date, and studies on F-box protein are currently focused on model plants or herbaceous plants. Therefore, this study is helpful to understand the molecular mechanism of involvement of F-box protein involved in drought tolerance and has the potential to be utilized in molecular breeding to improve drought stress tolerance in woody plants.