Genome-wide analysis of Myo-inositol oxygenase gene family in tomato reveals their involvement in ascorbic acid accumulation

Shoaib Munir,Guolin Zhou,Muhammad Ali Mumtaz,Weifang Chen,John Kojo Ahiakpa,Yuyang Zhang,Yuyang Zhang,Wei Zheng,Zhibiao Ye,Genzhong Liu

doi:10.1186/s12864-020-6708-8

Shoaib Munir, Guolin Zhou + Show 8 more

Open Access

https://doi.org/10.1186/s12864-020-6708-8

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Abstract

BackgroundAscorbic acid (Vitamin C, AsA) is an antioxidant metabolite involved in plant development and environmental stimuli. AsA biosynthesis has been well studied in plants, and MIOX is a critical enzyme in plants AsA biosynthesis pathway. However, Myo-inositol oxygenase (MIOX) gene family members and their involvement in AsA biosynthesis and response to abiotic stress remain unclear.ResultsIn this study, five tomato genes encoding MIOX proteins and possessing MIOX motifs were identified. Structural analysis and distribution mapping showed that 5 MIOX genes contain different intron/exon patterns and unevenly distributed among four chromosomes. Besides, expression analyses indicated the remarkable expression of SlMIOX genes in different plant tissues. Furthermore, transgenic lines were obtained by over-expression of the MIOX4 gene in tomato. The overexpression lines showed a significant increase in total ascorbate in leaves and red fruits compared to control. Expression analysis revealed that increased accumulation of AsA in MIOX4 overexpression lines is possible as a consequence of the multiple genes involved in AsA biosynthesis. Myo inositol (MI) feeding in leaf and fruit implied that the Myo-inositol pathway improved the AsA biosynthesis in leaves and fruits. MIOX4 overexpression lines exhibited a better light response, abiotic stress tolerance, and AsA biosynthesis capacity.ConclusionsThese results showed that MIOX4 transgenic lines contribute to AsA biosynthesis, evident as better light response and improved oxidative stress tolerance. This study provides the first comprehensive analysis of the MIOX gene family and their involvement in ascorbate biosynthesis in tomato.

Highlights

Ascorbic acid (Vitamin C, AsA) is an antioxidant metabolite involved in plant development and environmental stimuli
Identification, sequence alignment and phylogenetic analysis of tomato Myo-inositol oxygenase (MIOX) genes Four Arabidopsis MIOX protein sequences were downloaded from the TAIR database as queries for homologous sequences in the tomato genome database as described in methods
The nucleotide sequences, amino acids, theoretical isoelectric point, molecular weight (Mw), sequence length, and other relevant information were obtained from the Sol Genomics Network (SGN) or ExPASy-ProtParam database (Table 1)

Summary

Introduction

Ascorbic acid (Vitamin C, AsA) is an antioxidant metabolite involved in plant development and environmental stimuli. Myo-inositol oxygenase (MIOX) gene family members and their involvement in AsA biosynthesis and response to abiotic stress remain unclear. Ascorbic acid (Vitamin C, AsA) is a ubiquitous metabolite in plants which is involved in resistance to environmental stresses. The discovery of plant AsA biosynthesis pathways makes it possible to increase its content in plants by regulating the expression of genes involved in this pathway for improved nutritive values and enhanced tolerance to environmental stresses. Plants rely on different alternate routes for AsA synthesis like the Dmannose/L-galactose (Man/Gal), L-gulose, Dgalacturonate (GalU), and Myo-inositol pathways [4]

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