为深入探究HD-Zip转录因子家族成员GLABRA2(GL2)在杨树(Populus spp.)根毛生长发育中的作用，对吴屯杨(P. wutunensis)GL2基因进行克隆，同时进行生物信息学分析和组织特异性表达分析，并通过在拟南芥〔Arabidopsis thaliana (Linn.) Heynh.〕中过表达PwGL2分析该基因的功能。结果显示：PwGL2的cDNA总长度为2 283 bp，编码760个氨基酸；PwGL2蛋白的相对分子质量为84 353.28，属于亲水性蛋白，定位于细胞核；该蛋白的三级结构主要为α螺旋和无规卷曲，且该蛋白具有HD结构域和START结构域，符合HD-Zip家族特征。同源比对和系统发育分析结果显示：PwGL2蛋白与另4种杨树的GL2蛋白亲缘关系较近，且与黄瓜（Cucumis sativus Linn.）的GL2蛋白聚在同一分支。组织特异性表达分析结果显示PwGL2基因在吴屯杨根中相对表达量最高。过表达PwGL2拟南芥根毛密度显著（P＜0.05）低于野生型，表明PwGL2可能为根毛发育的负调控因子。盐胁迫下，过表达PwGL2拟南芥中PwGL2基因的相对表达量显著升高，表明PwGL2参与植株耐盐性调控；而盐胁迫下，过表达PwGL2拟南芥中丙二醛含量显著高于野生型，表明PwGL2可能负调控植株对盐胁迫的耐受性。综上所述，PwGL2基因可能抑制吴屯杨根毛生长发育，并负调控植株耐盐性。

 To investigate the role of HD-Zip transcription factor family member GLABRA2 (GL2) in root hair growth and development of Populus spp., the GL2 gene of P. wutunensis was cloned, bioinformatics analysis and tissuespecific expression analysis were simultaneously performed, and the gene function was analyzed through overexpression PwGL2 in Arabidopsis thaliana (Linn.) Heynh. The results show that the total cDNA length of PwGL2 is 2 283 bp, encoding 760 amino acids; the relative molecular mass of PwGL2 protein is 84 353.28, which is a hydrophilic protein and is localized in nucleus; the tertiary structure of this protein mainly consists of α-helixes and random coils, and it contains both HD domain and START domain, which is consistent with HD-Zip family characteristics. The homology alignment and phylogenetic analysis results show that the relationships between PwGL2 protein and GL2 proteins of other four Populus spp. are relatively close, and are clustered into one branch with GL2 protein of Cucumis sativus Linn. The tissue specific expression analysis result shows that the relative expression of PwGL2 gene is the highest in roots of P. wutunensis. The root hair density of PwGL2-overexpression A. thaliana is significantly (P<0.05) lower than that of wild type, suggesting that PwGL2 may act as a negative regulator of root hair development. Under salt stress, the relative expression of PwGL2 gene significantly increases in PwGL2overexpression A. thaliana, indicating that PwGL2 is involved in salt tolerance regulation of plant; while malondialdehyde content in PwGL2overexpression A. thaliana is significantly higher than that in wild type under salt stress, indicating that PwGL2 may negatively regulate salt tolerance of plant. In conclusion, PwGL2 gene may inhibit root hair growth and development of P. wutunensis, and negatively regulate plant salt tolerance.