AUTHOR=Kaur Navneet , Pandey Ashutosh , Shivani  , Kumar Prateek , Pandey Pankaj , Kesarwani Atul K. , Mantri Shrikant S. , Awasthi Praveen , Tiwari Siddharth 

TITLE=Regulation of Banana Phytoene Synthase (MaPSY) Expression, Characterization and Their Modulation under Various Abiotic Stress Conditions

JOURNAL=Frontiers in Plant Science

VOLUME=8

YEAR=2017

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2017.00462

DOI=10.3389/fpls.2017.00462

ISSN=1664-462X

ABSTRACT=<p>Phytoene synthase (PSY) is a key regulatory enzyme of carotenoid biosynthesis pathway in plants. The present study examines the role of PSY in carotenogenesis and stress management in banana. Germplasm screening of 10 Indian cultivars showed that Nendran (3011.94 μg/100 g dry weight) and Rasthali (105.35 μg/100 g dry weight) contained the highest and lowest amounts of β-carotene, respectively in ripe fruit-pulp. Nendran ripe pulp also showed significantly higher antioxidant activity as compared to Rasthali. Meta-analysis of three banana <italic>PSY</italic> genes (<italic>MaPSY1, MaPSY2</italic>, and <italic>MaPSY3</italic>) was performed to identify their structural features, subcellular, and chromosomal localization in banana genome. The distinct expression patterns of <italic>MaPSY1, MaPSY2</italic>, and <italic>MaPSY3</italic> genes were observed in various tissues, and fruit developmental stages of these two contrasting cultivars, suggesting differential regulation of the banana <italic>PSY</italic> genes. A positive correlation was observed between the expression of <italic>MaPSY1</italic> and β-carotene accumulation in the ripe fruit-peel and pulp of Nendran. The presence of stress responsive <italic>cis</italic>-regulatory motifs in promoter region of <italic>MaPSY</italic> genes were correlated with the expression pattern during various stress (abscisic acid, methyl jasmonate, salicylic acid and dark) treatments. The positive modulation of <italic>MaPSY1</italic> noticed under abiotic stresses suggested its role in plant physiological functions and defense response. The amino acid sequence analysis of the PSY proteins in contrasting cultivars revealed that all PSY comprises conserved domains related to enzyme activity. Bacterial complementation assay has validated the functional activity of six PSY proteins and among them PSY1 of Nendran (Nen-PSY1) gave the highest activity. These data provide new insights into the regulation of <italic>PSY</italic> expression in banana by developmental and stress related signals that can be explored in the banana improvement programs.</p>