Lack of the CCT domain changes the ability of mango MiCOL14A to resist salt and drought stress in Arabidopsis.

CONSTANS (CO) is the key gene in the photoperiodic pathway that regulates flowering in plants. In this paper, a CONSTANS-like 14A (COL14A) gene was obtained from mango, and its expression patterns and functions were characterized. Sequence analysis shows that MiCOL14A-JH has an additional A base, which leads to code shifting in subsequent coding boxes and loss of the CCT domain. The MiCOL14A-JH and MiCOL14A-GQ genes both belonged to group Ⅲ of the CO/COL gene family. Analysis of tissue expression patterns showed that MiCOL14A was expressed in all tissues, with the highest expression in the leaves of seedling, followed by lower expression levels in the flowers and stems of adult leaves. However, there was no significant difference between different mango varieties. At different development stages of flowering, the expression level of MiCOL14A-GQ was the highest in the leaves before floral induction period, and the lowest at flowering stage, while the highest expression level of MiCOL14A-JH appeared in the leaves at flowering stage. The transgenic functional analysis showed that both MiCOL14A-GQ and MiCOL14A-JH induced delayed flowering of transgenic Arabidopsis. In addition, MiCOL14A-JH enhanced the resistance of transgenic Arabidopsis to drought stress, while MiCOL14A-GQ increased the sensitivity of transgenic Arabidopsis to salt stress. Further proteinprotein interaction analysis showed that MiCOL14A-JH directly interacted with MYB30-INTERACTING E3 LIGASE 1 (MiMIEL1), CBL-interacting protein kinase 9 (MiCIPK9) and zinc-finger protein 4 (MiZFP4), but MiCOL14A-GQ could not interact with these three stress-related proteins. Together, our results demonstrated that MiCOL14A-JH and MiCOL14A-GQ not only regulate flowering but also play a role in the abiotic stress response in mango, and the lack of the CCT domain affects the proteinprotein interaction, thus affecting the gene response to stress. The insertion of an A base can provide a possible detection site for mango resistance breeding.