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

Abstract

The content of stone cells has significant effects on the flavour and quality of pear fruit. Previous research suggested that lignin deposition is closely related to stone cell formation. In the lignin biosynthetic pathway, cinnamoyl-CoA reductase (CCR) and cinnamyl alcohol dehydrogenase (CAD), dehydrogenase/reductase family members, catalyse the last two steps in monolignol synthesis. However, there is little knowledge of the characteristics of the CCR and CAD families in pear and their involvement in lignin synthesis of stone cells. In this study, 31 CCRs and 26 CADs were identified in the pear genome. Phylogenetic trees for CCRs and CADs were constructed; key amino acid residues were analysed, and three-dimensional structures were predicted. Using quantitative real-time polymerase chain reaction (qRT-PCR), PbCAD2, PbCCR1, -2 and -3 were identified as participating in lignin synthesis of stone cells in pear fruit. Subcellular localization analysis showed that the expressed proteins (PbCAD2, PbCCR1, -2 and -3) are found in the cytoplasm or at the cell membrane. These results reveal the evolutionary features of the CCR and CAD families in pear as well as the genes responsible for regulation of lignin synthesis and stone cell development in pear fruit.

Identification of Homeobox Genes Associated with Lignification and Their Expression Patterns in Bamboo Shoots

“…The genes without autonomous transcriptional activities were constructed using pGBKT7 or pGADT7, respectively. The recombinant plasmids were co-transformed into yeast strain AH109 and then plated on selective media (SD/−Leu/−Trp and SD/−Leu/−Trp/−His/−Ade/X-α-GAL) to screen for positive clones [52].…”

Effects of Metaxenia on Stone Cell Formation in Pear (Pyrus bretschneideri) Based on Transcriptomic Analysis and Functional Characterization of the Lignin-Related Gene PbC4H2

“…The Wiesner method carried out the histochemical staining of the stone cells of the pear fruit [18]. The transmission electron microscopy (TEM) observation of the SCW of stone cells was performed in accordance with the method that was described by Jin et al [8].…”

“…Therefore, we systematically compared the structural gene expression profiles in the lignin biosynthesis, transport, and polymerization pathways of pear fruit ( Supplementary Table S7 and Figure S3). We previously analysed members of the 4CL (4-coumarate: CoA ligase), OMT (O-methyltransferase), CCR (cinnamoyl CoA reductase), CAD (cinnamyl alcohol dehydrogenase), UGT (family-1 uridine diphosphate-glycosyltransferases), and DIR (dirigent) gene families [11,17,18,40]. Therefore, members of these gene families have a fixed nomenclature.…”

“…Phenylalanine ammonia-lyase (PAL) and cinnamate 4-hydroxylase (C4H) are the key enzymes responsible for the synthesis of cinnamic acid and p-coumaric acid, respectively [14,15]. Although in silico analysis of some gene families that are related to pear lignin synthesis has been reported, it is unclear which families play a major role in stone cell lignification, and the function of most lignin metabolism-related members has not been validated [10,11,[16][17][18][19][20].…”

Molecular Characterization and Expression of the Cinnamyl Alcohol Dehydrogenase Gene Family in Sweet Potato (Ipomoea batatas) under Environmental Stresses

“…Many CAD genes in several plants have been studied. This gene belongs to a multigene family, with 9 members in Arabidopsis (Kim et al, 2004), 14 members in sorghum (Saballos et al, 2009), 12 members in rice (Tobias and Chow, 2005), 16 members in poplar (Barakat et al, 2009), and 26 members in pear fruit (Cheng et al, 2017). These CAD isoforms showed differential expression during plant development and environmental conditions and might have different kinetics and substrate preferences.…”