Dwarf phenotype induced by overexpression of a GAI1-like gene from Rhus chinensis

DELLA proteins are a class of negative regulator of gibberellin signaling pathway and involved in diverse aspects of plant growth and development. However, the functions of DELLA homologous genes are largely unknown in Rhus chinensis. In this study, the full-length cDNA of RcGAI1L was isolated by reverse transcription (RT-PCR) method, which encoded 264 amino acids. Sequence analysis indicated that RcGAI1L only contained GRAS domain and amino acid sequence shared high identity with other plant species. Phylogenetic analysis showed that R. chinensis was the most closely related to Solanum pennellii. Quantitative reverse transcription PCR (qRT-PCR) analysis demonstrated that the expression of RcGAI1L was significantly down-regulated from the initial to terminal stage of gall development. The expression level of RcGAI1L was highest in leaf without gall, and lowest in galled leaf. Correlation analysis revealed that the expression of RcGAI1L was negatively correlated with GA content and gall volume. In addition, overexpression RcGAI1L in Arabidopsis led to a clear reduction in plant height, dry height, stem diameter, and delayed flowering compared to the wild-type plants. Taken together, these results suggest that RcGAI1L may negatively regulate GA response to affect gall development. This study provides new insights into the function of RcGAI1L gene in GA signaling and contributes to reveal the molecular regulatory mechanism of gall development.