毛竹7个COBL基因的分子特征及表达分析

Molecular Characteristics and Expression Analysis of Seven COBL Genes of Moso Bamboo(Phyllostachys edulis)

COBL家族基因编码糖基磷脂酰基醇锚定蛋白,主要参与调控植物细胞壁纤维素的含量和细胞的定向伸长。研究毛竹COBL基因的分子特征和表达模式,对揭示其材性快速形成机制具有重要意义。利用生物信息学方法对毛竹COBL家族成员进行全基因组分析,共鉴定出7个具有完整保守结构域的COBL家族基因成员(Pe COBL1~Pe COBL7),其内含子数量为0~7个,编码的蛋白均具有CCVS保守结构域和潜在的ω位点,仅4个成员(Pe COBL3,Pe COBL4,Pe COBL5和Pe COBL7)具有CBM功能域。亚细胞定位预测表明,Pe COBLs均定位于细胞膜上,为膜蛋白,属于GPI-APs超家族。系统进化与蛋白motifs预测分析发现,Pe COBLs各成员与水稻的亲缘关系更为接近,其氨基酸序列同源性更高。RT-q PCR结果显示,Pe COBLs在毛竹不同组织中的表达存在明显差异,其中在展开叶中表达量高(低)的基因,在未展开叶中表达量则相对较低(高);Pe COBLs在毛竹不同高度笋基部第一节的上、中、下三部分的表达量均存在一定的差异。基因共表达分析表明,Pe COBLs与多种蛋白酶基因呈现正向共表达,其中包含纤维素酶5和类纤维素合成酶D2基因,表明Pe COBLs参与纤维素合成的功能是与其他基因共同实现的。本研究为深入开展Pe COBLs功能研究提供了参考,有助于揭示该家族成员在调控毛竹纤维素含量和细胞定向伸长中的作用机制。

The genes in the COBL family encode glycosylphosphatidylinositol-anchored proteins(GPI-APs),which are mainly involved in regulating the cellulose content of plant cell walls and the directional elongation of cells.Study on the molecular characteristics and expression patterns of the COBL genes in moso bamboo(Phyllostachys edulis)is of great significance to reveal the rapid formation mechanism of bamboo material.Whole-genome identification of the members belonged to COBL family in moso bamboo was carried out by using the bioinformatics method.A total of seven members(PeCOBL1~PeCOBL7)with the complete conserved domain of COBL were identified,and their intron numbers ranged from 0 to 7.The proteins encoded by PeCOBLs all had CCVS conserved domain and potentialω-site,only four members(PeCOBL3,PeCOBL4,PeCOBL5 and PeCOBL7)had the CBM functional domain.The prediction of subcellular localization indicated that PeCOBLs were located on the cell membrane and were membrane proteins,belonging to the GPI-APs superfamily.Phylogenetic analysis and protein motifs prediction revealed that the members of PeCOBLs were more closely related to those of rice and had higher amino acid sequence homology.The results of RT-qPCR showed that there were significant differences in the expression of PeCOBLs in different tissues of moso bamboo,among which the genes with high(low)expression levels in the expanded leaves were relatively low(high)in the unexpanded leaves.There were also some differences in the expression of PeCOBLs in the top,middle and bottom parts of the first internode at the base of moso bamboo shoots with different heights.Gene co-expression analysis demonstrated that PeCOBLs were positively co-expressed with various protease genes,such as cellulase 5 and cellulose-like synthetase D2 gene,indicating that the function of PeCOBLs involved in cellulose synthesis might be achieved together with other genes.This study provides a reference for further research on the function of PeCOBLs,which will help reveal the mechanism of each member associated with the regulation of cellulose content and cell-directed elongation in moso bamboo.