Genome-Wide Analysis and Abiotic Stress-Responsive Patterns of COBRA-like Gene Family in Liriodendron chinense.

ABSTRACT

The COBRA gene encodes a plant-specific glycosylphosphatidylinositol (GPI)-anchored protein (GAP), which plays an important role in cell wall cellulose deposition. In this study, a total of 7 COBRA-like (COBL) genes were identified in the genome of the rare and endangered woody plant Liriodendron chinense (L. chinense). Phylogenetic analysis showed that these LcCOBL genes can be divided into two subfamilies, i.e., SF I and II. In the conserved motif analysis of two subfamilies, SF I contained 10 predicted motifs, while SF II contained 4-6 motifs. The tissue-specific expression patterns showed that LcCOBL5 was highly expressed in the phloem and xylem, indicating its potential role in cellulose biosynthesis. In addition, the cis-element analysis and abiotic stress transcriptomes showed that three LcCOBLs, LcCOBL3, LcCOBL4 and LcCOBL5, transcriptionally responded to abiotic stresses, including cold, drought and heat stress. In particular, the quantitative reverse-transcription PCR (qRT-PCR) analysis further confirmed that the LcCOBL3 gene was significantly upregulated in response to cold stress and peaked at 24-48 h, hinting at its potential role in the mechanism of cold resistance in L. chinense. Moreover, GFP-fused LcCOBL2, LcCOBL4 and LcCOBL5 were found to be localized in the cytomembrane. In summary, we expect these results to be beneficial for research on both the functions of LcCOBL genes and resistance breeding in L. chinense.