Transcriptome analysis of flowering genes in mango (Mangifera indica L.) in relation to floral malformation

Flowering is a complicated developmental process of physiological and morphological stages under the control of a number of external signals and internal factors. Floral malformation occurring during flower development stage is serious constraint having crippling effect on mango flowering and production leading to heavy economic losses. In mango there is lack of information about the gene expression profile during flower development. We therefore performed transcriptome analysis of Mangifera indica cultivar Amrapalli, by isolating total RNA from different stages of bud development in healthy and malformed tissues. The next generation sequencing were performed using 2 × 150 PE chemistry on the Illumina NextSeq platform resulting in 20.31, 20.77, 20.32, 27.92 and 18.59 million PE reads in MB-1, MB-2, MB-3, HB-1 and HB-2 stages respectively. Higher differential expressions copy numbers of seven flowering genes (MYB30, TPL, bHLH, FTIP1, CDKC2, CPK33, and ATH1) were observed in both the healthybud and panicle development stages as compared to malformed bud development stages. Among the other differentially expressed pattern of flowering genes in six possible combinations, the highly upregulated genes are UBP12, EFS, AGL8, AGL14, AGL20, AGL24, KIN10, MYB30, SUS2, FTIP1, CCT and LDL2 and down regulated genes were like TIL1, TIC, DCL3, GA20OX3, CCT, AP1, AGL6, AGL8, MYB30, AGL8, GCT and GA3OX1. The data set provides information on transcripts putatively associated with embryonic flower, earlier flowering, flowering time control, terminal flower and mads-box protein in healthy and malformed tissues. Out of the observed differentially expressed genes, the transcript profiles of GA20OX3, AGL24 and LDL2, the key genes regulating floral transition and differentiation, were validated through qRT-PCR. Our study provides a resource for exploring the complex molecular mechanisms in flower development and malformations in mango.