Open AccessComprehensive genome-wide analysis of the pear (Pyrus bretschneideri) laccase gene (PbLAC) family and functional identification of PbLAC1 involved in lignin biosynthesis
Author(s) -
Xi Cheng,
Guohui Li,
Chenhui Ma,
Muhammad Abdullah,
Jinyun Zhang,
Hai Zhao,
Qing Jin,
Yongping Cai,
Yi Lin
Publication year - 2019
Publication title -
plos one
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.99
H-Index - 332
ISSN - 1932-6203
DOI - 10.1371/journal.pone.0210892
Subject(s) - lignin , pear , biology , cell wall , prunus , gene family , genome , gene , botany , monolignol , arabidopsis , genetics , biosynthesis , mutant
The content and size of stone cell clusters affects the quality of pear fruit, and monolignol polymerization and deposition in the cell walls constitute a required step for stone cell formation. Laccase (LAC) is the key enzyme responsible for the polymerization of monolignols. However, there are no reports on the LAC family in pear ( Pyrus bretschneideri ), and the identity of the members responsible for lignin synthesis has not been clarified. Here, 41 LAC s were identified in the whole genome of pear. All Pyrus bretschneideri LAC s ( PbLAC s) were distributed on 13 chromosomes and divided into four phylogenetic groups (I-IV). In addition, 16 segmental duplication events were found, implying that segmental duplication was a primary reason for the expansion of the PbLAC family. LAC s from the genomes of three Rosaceae species ( Prunus mummer , Prunus persica , and Fragaria vesca ) were also identified, and an interspecies collinearity analysis was performed. The phylogenetic analysis, sequence alignments and spatiotemporal expression pattern analysis suggested that PbLAC1 , 5 , 6 , 29 , 36 and 38 were likely associated with lignin synthesis and stone cell formation in fruit. The two target genes of Pyr-miR1890 (a microRNA identified from pear fruit that is associated with lignin and stone cell accumulation), PbLAC1 and PbLAC14 , were selected for genetic transformation. Interfamily transfer of PbLAC1 into Arabidopsis resulted in a significant increase (approximately 17%) in the lignin content and thicker cell walls in interfascicular fibre and xylem cells, which demonstrated that PbLAC1 is involved in lignin biosynthesis and cell wall development. However, the lignin content and cell wall thickness were not changed significantly in the PbLAC14 -overexpressing transgenic Arabidopsis plants. This study revealed the function of PbLAC1 in lignin synthesis and provides important insights into the characteristics and evolution of the PbLAC family.