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

Abstract

Background Ascorbic 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. Results In 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. In addition, expression analyses indicated the remarkable expression of SlMIOX genes in different plant tissues. Furthermore, transgenic lines were obtained by over-expression of 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 AsA biosynthesis was mainly improved by Myo-inositol pathway in leaves and fruits. MIOX4 overexpression lines exhibited a betterlight response, abiotic stress tolerance, and AsA biosynthesis capacity. Conclusions These 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 MIOX gene family and their involvement in ascorbate biosynthesis in tomato.

A Transcriptional Analysis of the Genes Involved in the Ascorbic Acid Pathways Based on a Comparison of the Juice and Leaves of Navel and Anthocyanin-Rich Sweet Orange Varieties

“…This is the first time that the MyoIPS gene has been investigated in citrus. Our data highlighted its potential involvement, together with MyoOx , in the leaves, in accordance with previous studies [ 29 , 71 ]. However, other studies assert that MyoOx contributes minimally to the AsA content in the leaf tissue [ 25 , 28 ].…”

Genome-Wide Identification and Characterization of The MIOX Gene Family in Cotton

“…MIOX proteins are conserved and present in nearly all eukaryotes. MIOX is crucial in abiotic stress tolerance and previous studies on the MIOX gene family have been performed in many plants [2,5], including Arabidopsis thaliana [3,4], Oryza sativa [9] and Solanum lycopersicum [24]. In this study, we performed a comprehensive identi cation of MIOX genes in 5 tetraploid cotton species, 3 diploid cotton species and a cotton closely related species Gossypioides kirkii, with an aim of understanding the important and diverse roles of this gene family in abiotic stress tolerance in plants.…”

Methylation profiling of biosynthetic genes reveals the role of D-galacturonic acid reductase in ascorbic acid accumulation in tomato fruit

“…In higher plants, major biosynthesis pathways of L-ascorbic acid have been clari ed, including the Dmannose/L-galactose pathway, D-glucosone pathway, D-galacturonate and myo-inositol pathway (Wheeler et al, 1998;Lorence et al, 2004;Bulley and Laing, 2016). In tomato, multiple enzymes are involved in each biosynthesis pathway, including GDP-D-mannose pyrophosphorylase (GMP), GDP-Dmannose-3,5-epimerase (GME), GDP-L-galactose-phosphorylase (GGP), L-galactose-1-P phosphatase (GPP), L-galactose dehydrogenase (GalDH); L-galactono-1,4-lactone dehydrogenase (GLDH), Myo-inositol oxygenase (MIOX) and D-galacturonate reductase (GalUR) (Smirnoff and Wheeler, 2000;Davey et al, 2006;Zou et al, 2006;Mellidou and Kanellis, 2017;Munir et al, 2020). In plants, reduced L-ascorbic acid can be oxidized by ascorbate peroxidase (APX) and ascorbate oxidase (AO) (Bulley and Laing, 2016).…”