Genome-wide identification of the COBRA-Like gene family in Pinus tabuliformis and the role of PtCOBL12 in the regulation of cellulose biosynthesis

Abstract

COBRA-Like (COBL) genes encoding a plant-specific glycosylphosphatidylinositol (GPI) anchored protein, which have been proven to be key regulators in the cell expansion process and cellulose crystallinity. However, the function of COBL genes remains to be further elucidated in Pinus tabuliformis. We analyzed the P. tabuliformis genome and identified 15 COBL genes, which were anchored on 12 chromosomes and divided into three subgroups. Furthermore, we selected four COBL genes to explore their expression patterns in different seasons. The quantitative PCR results showed that COBL genes were mainly highly expressed in the active stage. Meanwhile, we analyzed the P. tabuliformis at different ages, and the expression level of the COBL genes in adult P. tabuliformis was much higher than that in juvenile. Most importantly, we found that PtCOBL12 overexpression in Arabidopsis thaliana improved plant growth and increased the cellulose content and relative crystallinity. Under drought stress, the germination rate and root length of transgenic plants were significantly higher than those of wild-type. Single-particle tracking analysis results showed that the particle velocity, dwell time, and motion range of PtCOBL12 on the plasma membrane increased significantly under drought conditions. Taken together, these results further clarify the molecular mechanism of COBL genes in the growth and development of conifers and provide a new view of the molecular dynamic model of COBL genes in response to drought stress.