摘　要：谷子白发病是威胁谷子产量和品质的重要系统性侵染病害。在抵抗病原菌的过程中，抗病相关基因起着尤为重要的作用。几丁质酶（Chitinase，EC.3.2.1.14）是植物抗病反应过程中的一类重要的病程相关蛋白，在植物防御病原菌侵染和害虫危害中扮演重要的角色。本研究在前期对白发病菌侵染抗感谷子品种转录组分析的基础上发现几丁质酶家族基因在抗感品种中显著差异表达，推测该家族基因可能参与谷子对白发病的抗病反应过程。基于此，本研究运用生物信息学相关技术对筛选出的30个谷子候选抗病相关几丁质酶家族基因进行染色体定位，利用TBtools等软件对该基因家族的理化性质、基因结构、发育树构建、蛋白序列及其转录水平进行分析。结果表明，30 个谷子几丁质酶家族基因分布在8条染色体上（第6条染色体除外）。几丁质酶蛋白均含有分泌信号肽，预测为分泌蛋白，且具有保守蛋白基序。系统发育树分析显示，该基因家族成员可分为3个亚组。结合白发病菌侵染抗感谷子转录组数据，根据其表达模式的差异，可分为上调、下调和不表达3 类基因。荧光定量 PCR 结果表明，Seita.1G225300、Seita.4G286000、Seita.5G389900、Seita.7G150600、Seita.7G150700和Seita.8G076900这些基因表达在抗感品种中存在显著差异，很可能参与抗白发病的调控过程。其研究结果有望为谷子抗病基因克隆及分子育种提供一定的理论参考。
关键词：谷子；白发病菌；几丁质酶；基因家族；抗病
中图分类号：S515                              文献标志码：ADOI：10.3969/j.issn.1007-7146.2022.04.011

Abstract: Downy mildew is an important systemic disease that reduces the yield and quality of foxtail millet. In the process of foxtail millet resisting to pathogen, resistance genes play a particularly important role. Chitinases (EC,3.2.1.14) are important pathogenesis-related protein families in plant disease resistance. They play a key role in the process of plant defense against pathogen and pest damage. In this study, based on the transcriptome analysis of  Sclerospora graminicola-infected resistant and susceptible foxtail millet varieties in the early-stage, it was found that the chitinase family genes were significantly differentially expressed in resistant and susceptible varieties. It is speculated that this family genes might be involved in the regulation of foxtail millet resistance. Therefore, we performed series of bioinformatics assays and experiments on these genes. The locations of 30 selected chitinase family genes in chromosomes were revealed by bioinformatics techniques. TBtools and other software were used to analyze the physical and chemical properties, gene structure, phylogenetic tree construction, protein conserved domain. Transcriptional expressions of chitinase genes were measured by quantitative PCR. The results showed that 30 chitinase genes were distributed on 8 chromosomes except chromosome 6. All chitinase proteins are predicated to be secreted proteins and they all have conserved motifs. Phylogenetic tree analysis revealed that the gene family members could be divided into three subgroups. Combined with the transcriptome data of resistant and susceptible varieties infected by S.graminicola, the expression of up-regulated and down-regulated genes were divided into three expression modes. The results of fluorescence quantitative PCR showed that Seita.1G225300, Seita.4G286000, Seita.5G389900, Seita.7G150600, Seita.7G150700 and Seita.8G076900 were significantly differentially expressed and most likely to be involved in S.graminicola and their expression trends were consistent with transcriptome data. The results are expected to provide a theoretical reference for cloning and molecular breeding of resistance genes in foxtail millet. 
Key words: foxtail millet; Sclerospora graminicola; chitinase; gene family; disease resistance
（Acta Laser Biology Sinica, 2022, 31(4): 368-378）