Identification and Sequence Analysis of β-D-Xylosidase Gene from Citrus grandis var. Shatinyu Hort

从沙田柚自交和异交花柱转录组测序中鉴定了β-D-木糖苷酶基因序列。该基因全长为2647 bp (GenBank登录号为KU925841)，开放阅读框(ORF)为2385 bp，共编码794个氨基酸，编码的蛋白质的分子量为87.30 kDa，理论等电点为5.87。β-D-木糖苷酶基因编码蛋白为亲水性蛋白，含有1个与糖基水解酶家族蛋白相同的保守CAS结构域。β-D-木糖苷酶基因在沙田柚在未授粉花柱中的表达量(RPKM)为0.07，自花授粉1、2、3 d花柱中的表达量(RPKM)分别为43.13、27.84、1.95，在异花授粉1、2、3 d花柱中基因的表达量(RPKM)则分别为33.90、76.14和49.63。系统进化树显示沙田柚β-D-木糖苷酶与甜橙(Citrus sinensis, XM_006468131)和克莱门柚(Citrus clementina, XM_006449591)亲缘关系很近，属于同一进化分支。 β-D-Xylosidase gene was identified from the transcriptome of the self-pollinated style and cross- pollinated style of Citrus grandis var. Shatinyu Hort. It is 2647 bp (GenBank accession number: KU925841) in length with an open reading frame (ORF) of 2385 bp, encoding 794 amino acids with deduced molecular weight of 87.30 kDa, and theoretical pI value of 5.87. Bioinformatics analysis showed that β-D-Xylosidase is a hydrophilic protein, and contained a same conserved CAS structure domain with the glycosyl hydrolase family. The expression of β-D-Xylosidase gene in unfertilized style was 0.07. in 1 - 3 day self-pollinated styles were 43.13, 27.84 and 1.95 respectively. Whereas, the expression of β-D-Xylosidase gene in 1 - 3 day cross-pollinated styles were 33.90, 76.14 and 49.63 respectively. Phylogenetic analysis revealed that β-D-Xylosidase showed closer kinship with that of Citrus sinensis and Citrus clementina, indicating that they belong to the same evolutionary branch.