Cloning and characterization of DELLA genes in Artemisia annua

Gibberellins (GA) are some of the most important phytohormones involved in plant development. DELLA proteins are negative regulators of GA signaling in many plants. In this study, the full-length cDNA sequences of three DELLA genes were cloned from Artemisia annua. Phylogenetic analysis revealed that AaDELLA1 and AaDELLA2 were located in the same cluster, but AaDELLA3 was not. Subcellular localization analysis suggested that AaDELLAs can be targeted to the nucleus and/or cytoplasm. Real-time PCR indicated that all three AaDELLA genes exhibited the highest expression in seeds. Expression of all AaDELLA genes was enhanced by exogenous MeJA treatment but inhibited by GA3 treatment. Yeast two-hybrid assay showed that AaDELLAs could interact with basic helix-loop-helix transcription factor AaMYC2, suggesting that GA and JA signaling may be involved in cross-talk via DELLA and MYC2 interaction in A. annua.