title: Genome-wide identification, classification and analysis of HD-ZIP gene family in citrus, and its potential roles in somatic embryogenesis regulation.
abstract: The homeodomain-leucine zipper (HD-Zip) transcription factors, which belong to a class of Homeobox proteins, has been reported to be involved in different biological processes of plants, including growth and development, photomorphogenesis, flowering, fruit ripening and adaptation responses to environmental stresses. In this study, 27 HD-Zip genes (CsHBs) were identified in Citrus. Based on the phylogenetic analysis and characteristics of individual gene or protein, the HD-Zip gene family in Citrus can be classified into 4 subfamilies, i.e. HD-Zip I, HD-Zip II, HD-Zip III, and HD-Zip IV containing 16, 2, 4, and 5 members respectively. The digital expression patterns of 27 HD-Zip genes were analyzed in the callus, flower, leaf and fruit of Citrus sinensis. The qRT-PCR and RT-PCR analyses of six selected HD-Zip genes were performed in six citrus cultivars with different embryogenic competence and in the embryo induction stages, which revealed that these genes were differentially expressed and might be involved in citrus somatic embryogenesis (SE). The results exhibited that the expression of CsHB1 was up-regulated in somatic embryo induction process, and its expression was higher in citrus cultivars with high embryogenic capacity than in cultivars recalcitrant to form somatic embryos. Moreover, a microsatellite site of three nucleotide repeats was found in CsHB1 gene among eighteen citrus genotypes, indicating the possible association of CsHB1 gene to the capacity of callus induction.
authors.affiliation: Key Laboratory of Horticultural Plant Biology (Ministry of Education), Huazhong Agricultural University, Wuhan 430070, China; Center of Applied Biotechnology, Wuhan Institute of Bioengineering, Wuhan 430415, China. Electronic address: gexiaoxia15@aliyun.com.
authors.forename: Xiao-Xia
authors.initials: XX
authors.lastname: Ge
authors.affiliation: Key Laboratory of Horticultural Plant Biology (Ministry of Education), Huazhong Agricultural University, Wuhan 430070, China.
authors.forename: Zheng
authors.initials: Z
authors.lastname: Liu
authors.affiliation: Key Laboratory of Horticultural Plant Biology (Ministry of Education), Huazhong Agricultural University, Wuhan 430070, China.
authors.forename: Xiao-Meng
authors.initials: XM
authors.lastname: Wu
authors.affiliation: Key Laboratory of Horticultural Plant Biology (Ministry of Education), Huazhong Agricultural University, Wuhan 430070, China.
authors.forename: Li-Jun
authors.initials: LJ
authors.lastname: Chai
authors.affiliation: Key Laboratory of Horticultural Plant Biology (Ministry of Education), Huazhong Agricultural University, Wuhan 430070, China. Electronic address: guoww@mail.hzau.edu.cn.
authors.forename: Wen-Wu
authors.initials: WW
authors.lastname: Guo
mesh_terms: D001483:Base Sequence; D002957:Citrus / Q000235:genetics*; D018506:Gene Expression Regulation, Plant / Q000235:genetics; D005801:Genes, Homeobox / Q000235:genetics*; D018745:Genome, Plant / Q000235:genetics*; D018398:Homeodomain Proteins / Q000235:genetics*; D016350:Leucine Zippers / Q000235:genetics*; D008969:Molecular Sequence Data; D010940:Plant Proteins / Q000235:genetics*; D014157:Transcription Factors / Q000235:genetics; D015854:Up-Regulation / Q000235:genetics
chemical_list: D018398:Homeodomain Proteins; D010940:Plant Proteins; D014157:Transcription Factors
keywords: Citrus; HD-Zip genes; Somatic embryogenesis