In-silico mining and characterisation of sweet genes in Mango (Mangifera indica L.)

The present study focuses on the insilico identiûcation of SWEET transporter coding genes in mango and its expression in leaf, root, unripe pulp, ripe pulp and jelly seed. Twelve different SWEET transcription factors genes/ transcripts (MiSWEET1, MiSWEET2, MiSWEET3, MiSWEET4, MiSWEET5, MiSWEET6, MiSWEET7, MiSWEET10, MiSWEET12, MiSWEET14, MiSWEET16, MiSWEET17) were mined in the fruit transcriptome data of mango jelly seed tissue. Motif 5 is the most conserved motif and seven amino acid residues in this motif are identical in nearly all SWEET members harbouring this motif. The proline (P, 5th), Leucine (L, 6th), Valine (V, 12th and 18th), Serine (S, 17th), Methionine (M, 21st), and Phenylalanine (F, 23rd) of motif 5 are largely conserved in this family, which might be important for sugar intercellular exchange in mango. To decipher the role of SWEET factors in this disorder, the expression analysis through semi-quantitative RT-PCR was analysed at root, leaf, unripe pulp, ripe pulp and jelly seed, revealing that these SWEET genes play developmental and ripening roles. Expression patterns of the SWEET genes during fruit development and ripening indicated that they may be involved in development and ripening by the ethylene signalling pathway. Our findings provide for further functional characterization of the SWEET family genes in mango and open the window of investigation of an important SWEET transcription factor family of genes and its role in mango fruit development and ripening.