The CONSTANS/CONSTANS-LIKE (CO/COL) gene family plays important roles in plants flowering and stress response. In this study, two variants of the MiCOL14B gene were identified from two different mango cultivars; they were designated as MiCOL14B-GQ and MiCOL14B-JH, which exhibited significant differences in sequence and B-box domain. Both genes were expressed in various tissues of mango, localized in the nucleus, and responsive to drought and salt stress. In transgenic Arabidopsis thaliana, MiCOL14B-GQ delayed flowering, while MiCOL14B-JH promoted flowering. This phenotypic divergence stemmed from their molecular regulatory specificity. Yeast one-hybrid (Y1H) and dual-luciferase reporter assays demonstrated that both variants directly bind to the promoters of florigen genes (MiFTs), with MiCOL14B-GQ repressing their transcription and MiCOL14B-JH enhancing it. Altered expression levels of MiFTs in the roots of transgenic mango further validated this mechanism. Moreover, both MiCOL14B-GQ and MiCOL14B-JH improved stress tolerance under drought and salt conditions in transgenic A. thaliana as well as in transgenic mango roots. These variants significantly increased stress tolerance by increasing proline (Pro) content and superoxide dismutase (SOD) activity, while reducing malondialdehyde (MDA) and hydrogen peroxide (H2O2) accumulation. Yeast two-hybrid (Y2H) and bimolecular fluorescence complementation (BiFC) assays revealed that MiCOL14B-GQ and MiCOL14B-JH interact with several stress-related proteins. This study demonstrates for the first time the functional effects of sequence variation in the MiCOL14B gene on flowering and stress responses, providing valuable genetic resources for mango molecular breeding.
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Zinc finger protein (ZFP) plays an important role in plant abiotic stress response. Therefore, to provide a theoretical basis for stress resistance breeding, this study aimed to analyze the response of two zinc finger protein genes of MiZAT10A and MiZAT10B transgenic Arabidopsis to abiotic stresses, such as salt, drought, heavy metals and exogenous hormones.
The promoter cis acting elements and motif of mango MiZAT10A and MiZAT10B genes were predicted and analyzed by online software PLACE and MEME, respectively. The chromosome location map was drawn by TBtools software and SiJiMi gene annotation file (GFF file and unpublished). Tissue expression patterns of MiZAT10A and MiZAT10B genes were analyzed by qRT-PCR. The overexpression vectors of MiZAT10A and MiZAT10B genes were constructed and transformed into Arabidopsis thaliana by Agrobacterium floral-dip method. The phenotype of MiZAT10A and MiZAT10B transgenic plant were observed and recorded under salt, drought, heavy metals, abscisic acid and gibberellin treatments.
Promoter cis element analysis showed that there were many light response elements, hormone response elements and abiotic stress response elements in the promoter region of MiZAT10A and MiZAT10B genes. Expression analysis showed that MiZAT10A and MiZAT10B were highly expressed in buds and flowers. 9 of MiZAT10A and 14 of MiZAT10B transgenic Arabidopsis strains were obtained. Overexpression of MiZAT10A and MiZAT10B significantly resulted early flowering compared with the control lines. The root length of MiZAT10A and MiZAT10B overexpressing transgenic Arabidopsis was significantly longer than that of control lines under salt stress, drought stress, heavy metal stress, GA3 and ABA hormone treatments.
Overexpression of MiZAT10A and MiZAT10B not only promoted transgenic Arabidopsis flowering early but also improved salt, drought, heavy metals and exogenous hormones GA3 and ABA resistance.
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