Comprehensive genome-wide analysis of the pear (Pyrus bretschneideri) laccase gene (PbLAC) family and functional identification of PbLAC1 involved in lignin biosynthesis
Comprehensive genome-wide analysis of the pear (Pyrus bretschneideri) laccase gene (PbLAC) family and functional identification of PbLAC1 involved in lignin biosynthesis
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DOI：
10.1371/journal.pone.0210892
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发表时间：
2019-02-12
期刊：
影响因子：
3.7
通讯作者：
Lin, Yi
中科院分区：
文献类型：
--
作者：
Cheng, Xi;Li, Guohui;Lin, Yi
石细胞团的含量和大小直接影响梨果实的品质，而石细胞团的聚合和在细胞壁中的沉积是石细胞形成的必要步骤。漆酶是木质素单体聚合的关键酶。然而，在梨（Pyrus bretschneideri）中没有关于LAC家族的报道，并且负责木质素合成的成员的身份尚未澄清。在梨全基因组中鉴定出41个拉克。所有的白梨拉克（PbLACs）均分布在13条染色体上，可分为4个系统发育群（I-IV）。此外，还发现了16个片段重复事件，这表明片段重复是PbLAC家族扩大的主要原因。还鉴定了来自三种蔷薇科物种（Prunus mummer、Prunus persica和Fragaria vesca）基因组的拉克，并进行了种间共线性分析。系统发育分析、序列比对和时空表达模式分析表明，PbLAC 1、5、6、29、36和38可能与果实中木质素合成和石细胞形成有关。选择Pyr-miR 1890（从梨果实中鉴定的与木质素和石细胞积累相关的microRNA）的两个靶基因PbLAC 1和PbLAC 14用于遗传转化。将PbLAC 1家族间基因转入拟南芥，可显著增加木质素含量（约17%），并使束间纤维和木质部细胞的细胞壁变厚，表明PbLAC 1参与木质素的生物合成和细胞壁的发育。然而，木质素含量和细胞壁厚度在PbLAC 14过表达的转基因拟南芥植株中没有显著变化。该研究揭示了PbLAC 1在木质素合成中的功能，并为PbLAC家族的特征和进化提供了重要的见解。
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 LACs were identified in the whole genome of pear. All Pyrus bretschneideri LACs (PbLACs) 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. LACs 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.