Genome-Wide Identification and Analyses of Drought/Salt-Responsive Cytochrome P450 Genes in Medicago truncatula.

Yaying Xia,Lin Ma,Yongzhen Pang,Junfeng Yang,Su Yan

doi:10.3390/ijms22189957

Abstract

Cytochrome P450 monooxygenases (P450s) catalyze a great number of biochemical reactions and play vital roles in plant growth, development and secondary metabolism. As yet, the genome-scale investigation on P450s is still lacking in the model legume Medicago truncatula. In particular, whether and how many MtP450s are involved in drought and salt stresses for Medicago growth, development and yield remain unclear. In this study, a total of 346 MtP450 genes were identified and classified into 10 clans containing 48 families. Among them, sixty-one MtP450 genes pairs are tandem duplication events and 10 MtP450 genes are segmental duplication events. MtP450 genes within one family exhibit high conservation and specificity in intron–exon structure. Meanwhile, many Mt450 genes displayed tissue-specific expression pattern in various tissues. Specifically, the expression pattern of 204 Mt450 genes under drought/NaCl treatments were analyzed by using the weighted correlation network analysis (WGCNA). Among them, eight genes (CYP72A59v1, CYP74B4, CYP71AU56, CYP81E9, CYP71A31, CYP704G6, CYP76Y14, and CYP78A126), and six genes (CYP83D3, CYP76F70, CYP72A66, CYP76E1, CYP74C12, and CYP94A52) were found to be hub genes under drought/NaCl treatments, respectively. The expression levels of these selected hub genes could be induced, respectively, by drought/NaCl treatments, as validated by qPCR analyses, and most of these genes are involved in the secondary metabolism and fatty acid pathways. The genome-wide identification and co-expression analyses of M. truncatula P450 superfamily genes established a gene atlas for a deep and systematic investigation of P450 genes in M. truncatula, and the selected drought-/salt-responsive genes could be utilized for further functional characterization and molecular breeding for resistance in legume crops.

Highlights

Cytochrome P450 monooxygenases (P450s) are one of the largest enzymatic protein families
Less than half (151) putative P450s genes were identified for M. truncatula in the previous study [17], and they were clustered into only 9 clans and 44 families
The number of the P450 genes is larger in M. truncatula than in Arabidopsis, with 264 genes and 47 families, which might be due to gene expansion in M. truncatula for the production of diverse compounds

Summary

Introduction

Cytochrome P450 monooxygenases (P450s) are one of the largest enzymatic protein families. P450s are present in most organisms, from bacteria to plants, animals and humans, and account for about 1% of the protein-coding genes in plants [1,2]. The E-R-R triad (EXXR and PXRX) is required for locking the heme pockets into position, and assures the stabilization of core structure. Among these conserved domains, only the E-R-R triad and the cysteine in the heme-binding domain are conserved in all plant P450 sequences, and they are signature motif of plant P450s [5,8,9]

Methods

Results

Conclusion