Overexpression of mango MiRZFP34 confers early flowering and stress tolerance in transgenic Arabidopsis

The RING zinc finger protein (RZFP) gene plays an important role in the response to stress in plants. In this study, full-length cDNA sequences of the RZFP homologous gene MiRZFP34 were obtained from mango. The open reading frame of MiRZFP34 is 858 bp in length and encodes 285 amino acids. Sequence analysis showed that MiRZFP34 had typical CHY zinc finger and RING-finger domains. Expression analysis showed that MiRZFP34 was highly expressed in flowers but was expressed at relatively low levels in juvenile tissues. Drought and low temperature treatment significantly upregulated the expression of MiRZFP34 in leaves. Transformation of Arabidopsis revealed that overexpression of MiRZFP34 promoted early flowering and significantly upregulated the expression levels of the flowering-related genes APETALA1 (AtAP1), FLOWERING LOCUS T (AtFT), and SUPPRESSOR OF OVEREXPRESSION OF CO1 (AtSOC1) in transgenic lines than WT plants. In addition, MiRZFP34-overexpressing lines showed resistance to drought and low temperature stress, which was accompanied by a higher expression of drought and low temperature responsive genes in these lines. Bimolecular fluorescence complementation (BiFC) assays showed that MiRZFP34 protein can interact with MiAP1-1, MiAP1-2, and MiCAL2. These results were the first to show that MiRZFP34 was involved in both flowering regulation and abiotic stress responses.