Proteomic landscape presents cues for vegetative to reproductive transition in mango

Abstract: Proteome-based vegetative and flower bud formation characterization was utilized to identify and differentiate protein species with significant variable abundance during floral transition in mango cv. Dashehari using 2DE and corroborated the identified protein spots using gene expression analysis. Total soluble proteins were phenol-extracted from mango cv's vegetative and floral flush. Dashehari and separated on 2D gels at pH 4-7. The protein spots with variable intensity were identified through SameSpots software. The protein sequences of differentially accumulated spots were identified based on PI and MW using Citrus sinensis proteome isoelectric focusing database. Furthermore, these protein sequences were used to conduct (tBLASTn) against Mangifera indica to predict the protein. Real time gene expression was done to corroborate identified proteins. Total 301 spots were detected, out of which 16 were identified as differentially expressed (P?0.05) and a 2-fold change. These 16 protein spots were identified on the basis of in silico comparative mapping protein against genome of mango and citrus, a close relative. They were classified into eight categories: transcriptional regulation, phenylpropanoid pathway and cell wall /cytoskeleton metabolism-related proteins, hormone signalling, flowering time, signal-transduction, transport and protein synthesis to flowering. Five genes coding for shortlisted proteins were used for validation of results using gene expression analysis. SAM (S adenosyl methonine synthase) was found up-regulated in floral flush, involved in the biosynthesis of polyamines has association with flowering, and stress responses. Furthermore, ARF (Auxin Response Factor), serine/threonine kinase gene members were also found to play critical role in determining floral development process in mango, consistent with results obtained through 2DE. Protein species that are putatively involved in phenylpropanoid pathway were also identified, showing the process of mango flowering from a new perspective beyond the conventional view. This flowering related proteomics study provides an overview of the biological pathways and regulatory mechanisms associated with flowering developmental physiology.