Bioinformatic and expression analysis of the OMT gene family in Pyrus bretschneideri cv. Dangshan Su

Abstract

ABSTRACT. With high nutritional value in its fruits, Dangshan Su pear has been widely cultivated in China. The stone cell content in fruits is a key factor affecting fruit quality in pear, and the formation of stone cells has been associated with lignin biosynthesis. O-Methyltransferase (OMT) is a key enzyme involved in lignin metabolism within the phenylpropanoid pathway. Here, we screened 26 OMT genes from the Pyrus bretschneideri cv. Dangshan Su genome using the DNATOOLs software. To characterize the OMT gene family in pear, gene structure, chromosomal localization, and conserved motifs of PbOMTs were analyzed. PbOMTs were divided into two categories, type I (designated PbCCOMTs) and type II (designated PbCOMTs), indicating the differentiation of function during evolution. Based on the analysis of multiple sequence alignment, cis-element prediction, and phylogenetic relationships, two candidate genes, PbCCOMT1 and PbCCOMT3, were selected for the analysis of temporal and spatial gene expression in pear. The promoter regions of both PbCCOMT1 and PbCCOMT3 contain regulatory motifs for lignin synthesis. Moreover, the two genes show high similarity and close phylogenetic relationships with CCOMTs in other species. Expression analysis showed that transcript levels of two PbCCOMTs were positively associated with the contents of both stone cells and lignin during the development of pear fruit. These results suggest that PbCCOMT1 and PbCCOMT3 are closely associated with lignin biosynthesis. These findings will help clarify the function of PbOMTs in lignin metabolism and to elucidate the mechanisms underlying stone cell formation in pear.

Characterization and analysis of CCR and CAD gene families at the whole-genome level for lignin synthesis of stone cells in pear (Pyrus bretschneideri) fruit

“…Factors such as the size, content and density of stone cells in pear are thought to greatly affect pear quality ( Jin et al, 2013 ; Cheng et al, 2016 ). It has been shown that the lignin content of mature stone cells is approximately 18% ( Lee et al, 2007 ).…”

Comparison of the transcriptomic analysis between two Chinese white pear (Pyrus bretschneideri Rehd.) genotypes of different stone cells contents

“…Dangshan Su is a pear variety originating in China that is known for its fruit, which bears a wealth of nutritional and medicinal value. ‘Dangshan Su’ has relatively high stone cell content in the fruit, which is a crucial factor influencing the quality of pear fruit by affecting not only sucrose and other nutrient contents but also flesh hardness and chewiness [ 1 , 2 ]. The ‘Lianglizaosu’ variety originated from a natural bud sport of ‘Dangshan Su’ pear.…”

PbMC1a/1b regulates lignification during stone cell development in pear (Pyrus bretschneideri) fruit

“…Stone cells are widely present in various parts of fruit, especially in the flesh, which reduces the quality of fruit [34][35][36] . Recent studies have focused on the cloning and regulation of lignin synthesis structural genes based on the pear genome and germplasm resources 37,38 .…”