Comparative Genome-Wide Analysis of the Malate Dehydrogenase Gene Families in Cotton.

Muhammad Imran,Jin-Yuan Liu,Kai Tang,Jinfa Zhang

doi:10.1371/journal.pone.0166341

Abstract

Malate dehydrogenases (MDHs) play crucial roles in the physiological processes of plant growth and development. In this study, 13 and 25 MDH genes were identified from Gossypium raimondii and Gossypium hirsutum, respectively. Using these and 13 previously reported Gossypium arboretum MDH genes, a comparative molecular analysis between identified MDH genes from G. raimondii, G. hirsutum, and G. arboretum was performed. Based on multiple sequence alignments, cotton MDHs were divided into five subgroups: mitochondrial MDH, peroxisomal MDH, plastidial MDH, chloroplastic MDH and cytoplasmic MDH. Almost all of the MDHs within the same subgroup shared similar gene structure, amino acid sequence, and conserved motifs in their functional domains. An analysis of chromosomal localization suggested that segmental duplication played a major role in the expansion of cotton MDH gene families. Additionally, a selective pressure analysis indicated that purifying selection acted as a vital force in the evolution of MDH gene families in cotton. Meanwhile, an expression analysis showed the distinct expression profiles of GhMDHs in different vegetative tissues and at different fiber developmental stages, suggesting the functional diversification of these genes in cotton growth and fiber development. Finally, a promoter analysis indicated redundant but typical cis-regulatory elements for the potential functions and stress activity of many MDH genes. This study provides fundamental information for a better understanding of cotton MDH gene families and aids in functional analyses of the MDH genes in cotton fiber development.

Highlights

Plant malate dehydrogenase (MDH, EC1.1.1.37) possesses multiple isoforms, and catalyzes the interconversion of malate and oxaloacetate (OAA) coupled to the reduction-oxidation of the NAD pool [1]
The results showed that most of the 25 G. hirsutum Malate dehydrogenases (MDHs) (GhMDHs) and 13 G. raimondii MDHs (GrMDHs) genes possessed signal sequences and were predicted to be located in the plastid, mitochondria and cytoplasm; only some genes were predicted to be located in the peroxisomes and chloroplast (Table 1)
Among the five detected GhMDHs, GhcMDH1 was significantly different from other members; this began to increase in fibers from 5 to 15 days post anthesis (DPA) and started to decline, implying that this gene plays a crucial role in fast fiber elongation (Fig 5A and 5B). These results indicate that GhcMDH1A and GhcMDH1D might jointly play a major role in fiber development, in the elongation stage of fiber

Summary

Introduction

Plant malate dehydrogenase (MDH, EC1.1.1.37) possesses multiple isoforms, and catalyzes the interconversion of malate and oxaloacetate (OAA) coupled to the reduction-oxidation of the NAD pool [1]. Comparative Analysis of MDH Gene Families in Cotton. Abundant MDH genes have been characterized from several plant species, including wheat [5], Arabidopsis [6], maize [7], apple [8] and cotton [9]. Among these MDH genes, the mitochondrial and cytosolic MDH genes are the most frequently investigated, likely because of their abundance in the plant kingdom. An increasing number of studies indicate that MDHs and their catalytic product malate are involved in several processes of plant growth and development, e.g., root growth [10], seed development [11], and leaf respiration [6]. MDHs play crucial roles in various biotic and abiotic stresses, such as pathogen [12], nutrient [9], salt and cold [8] stresses

Methods

Results

Discussion

Conclusion