S01 - Session O6 - Regulation of flowering in mango - a molecular perspective

Authors: Bal Krishna *, Sayali N Vyavahare, Sumersing I Patil, Prafullachandra Sane

Flowering is an important aspect of plant biology and in mango it is one of the most crucial events for commercial success of the crop. Flowering behaviour of many commercial mango cultivars is irregular and several flower in alternate years. The genetic factors associated with flowering operate through an intricate network of genes. In the past few years our group has been involved in characterization and expression studies of genes of flowering pathways in mango. The florigen or flowering factor known for a long time has now been identified as FLOWERING LOCUS T (FT) gene in a model plant. A homologue of the FT gene is also functional in mango and plays a central role in flowering regulation, It has at least three copies in the its genome. Structurally a close relative of FT, flowering repressors TERMINAL FLOWER LIKE 1 ( TFL1), MiTFL1 and MiTFL1a are also involved in regulation of flowering, especially in maintaining the vegetative phase in mango. The FLOWERING LOCUS D ( FD ) has also been identified by us in mango. Another important group of genes associated with flowering in mango are those regulated through the circadian rhythm. These include GIGENTIA ( GI ) , FLAVIN BINDING KELCH REPEAT F BOX 1 ( FKF1 ) , CYCLIC DOF FACTOR 1 LIKE ( CDF1 ) and CONSTANS ( CO ), with GI-FKF1-CDF1-CO working as a module and seems to be working in mango although it is a day-neutral crop. The presence of temperature-sensitive elements in the promoter region of MiGI2 may be the key to the temperature-dependent flowering regulation in mango. Other genes involved in regulation of mango flowering are SUPRESSOR OF OVEREXPRESSION OF CONSTANS1 ( SOC1 ) , SHORT VEGETATIVE PHASE ( SVP ) and APETALA 1. The micro RNA 172 (miR172) is a positive regulator and micro RNA 156 (miR156) is a negative regulator of flowering in mango. The interaction of above triggers ( MiCO1, MiCO2, MiFT1 , MiFT2 and MiFT3 , MiFD , MiGI2 , MiSOC1 and MiFKF1 ) and suppressors (MiCDF1, MiTFL1 , MiTFL1a , MiSVP and MiAP2) leads to ethe xpression of meristem identity genes APETALA 1 ( MiAP1-1 and MiAP1-2) and LEAFY ( MiLFY ), which regulate the development of floral organs.