Genome-wide Expression Analysis and Metabolite Profiling Elucidate Transcriptional Regulation of Flavonoid Biosynthesis and Modulation under Abiotic Stresses in Banana.

Ashutosh Pandey,Mehar H Asif,Deepika Lakhwani,Prabodh K Trivedi,Anshu Alok,Jagdeep Singh

doi:10.1038/srep31361

Abstract

Flavonoid biosynthesis is largely regulated at the transcriptional level due to the modulated expression of genes related to the phenylpropanoid pathway in plants. Although accumulation of different flavonoids has been reported in banana, a staple fruit crop, no detailed information is available on regulation of the biosynthesis in this important plant. We carried out genome-wide analysis of banana (Musa acuminata, AAA genome) and identified 28 genes belonging to 9 gene families associated with flavonoid biosynthesis. Expression analysis suggested spatial and temporal regulation of the identified genes in different tissues of banana. Analysis revealed enhanced expression of genes related to flavonol and proanthocyanidin (PA) biosynthesis in peel and pulp at the early developmental stages of fruit. Genes involved in anthocyanin biosynthesis were highly expressed during banana fruit ripening. In general, higher accumulation of metabolites was observed in the peel as compared to pulp tissue. A correlation between expression of genes and metabolite content was observed at the early stage of fruit development. Furthermore, this study also suggests regulation of flavonoid biosynthesis, at transcriptional level, under light and dark exposures as well as methyl jasmonate (MJ) treatment in banana.

Highlights

Due to the selective and differential synthesis of flavonoids, biological activities differ across plant species as well as in different tissues of a plant
Structural genes encoding enzymes involved in various intermediate steps of the flavonoid biosynthesis pathway were identified through BLAST searches in banana genome using protein from different plant species as query sequences
To achieve this, corresponding genomic sequences were retrieved, and gene models were modified using online tool (Fgenesh program) followed by manual analysis of the intron–exon boundaries. This analysis led to the identification of a total of 28 genes encoding enzymes involved in flavonoid biosynthesis pathway in banana (Supplementary File S1)

Summary

Introduction

Due to the selective and differential synthesis of flavonoids, biological activities differ across plant species as well as in different tissues of a plant These differences have been correlated with the tight spatial and temporal regulation of genes involved in the biosynthesis of different flavonoids. Depending upon cellular, climatic and developmental conditions These factors are major limitation for proper exploitation of secondary plant products in the drug as well as neutraceutical development. Out of different biosynthetic pathways leading to secondary plant product biosynthesis, the phenylpropanoid pathway (Fig. 1) is probably the best characterized in terms of enzymatic steps and regulatory genes. Banana is a staple fruit crop for a major world population, especially in developing countries Certain agronomic traits such as fruit quality and stress resistance are of great importance in this plant species. Correlation between expression of specific gene family member with various metabolites in different tissues and throughout the fruit development as well as during various abiotic stresses has been established

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Discussion

Conclusion