Interrelations of growth regulators, carbohydrates and expression of flowering genes (FT, LFY, AP1) in leaf and shoot apex of regular and alternate bearing mango (Mangifera indica L.) cultivars during flowering

Two mango cultivars, Amrapali (regular bearer) and Dashehari (alternate bearer), contrasting for bearing habit was assessed for endogenous phytohormone, carbohydrates and expression of floral inductive genes during flowering. Cultivar Amrapali had higher concentration of growth regulators like ABA, auxin, zeatin, salicylic acid and jasmonic acid and carbohydrates, whereas lower GA content compared to cv. Dashehari and the content increased during flowering when compared to vegetative stage. Gibberellic acid levels was higher in all the stages of bud growth in alternate bearer cv. Dashehari compared to the regular bearer cv. Amrapali. However, the starch content was higher in cv. Amrapali compared to cv. Dashehari. Studies on flower inducing genes indicated that the expression of MiLFY gene was found to be higher in the flowering panicles. Expression of MiFT gene was higher in regular bearer cv. Amrapali compared to the alternate bearer cv. Dashehari and the expression was observed only in leaves which are adjacent to the apical buds during flowering. Higher expression of MiAP1 gene was also observed in the leaves during the floral induction phase. MiFT and MiAP1 genes found to have a negative relation with gibberellic acid and its derivatives. The results indicate that positive regulators of flowering were higher in regular bearing cultivar Amrapali compared to alternate bearing cultivar Dashehari.