关键词: 黄瓜, CC-NBS-LRR（CNL）, 霜霉病, 白粉病, 基因表达

Abstract:

【Objective】 The bioinformatics and expression pattern analysis of the CC-NBS-LRR (CNL) gene family of the whole cucumber (Cucumis sativus) genome was carried out to provide a reference for further study of the functions of the CsCNL gene family in growth, development and disease stress response. 【Method】 Taking the CNL gene sequence of Arabidopsis thaliana as the reference, the genome of cucumber ‘9930’ was searched by local Perl language and Pfam software, and the members of CsCNL gene family were identified. CsCNL gene family was analyzed by some bioinformatics tools, such as ExPASY, GSDS2.0, MEGA, MEME, Tbtools and Mev. Transcriptome data, inoculating with downy mildew and powdery mildew pathogens (Pseudoperonospora cubensis and Podosphaera xanthii) and real-time quantitative PCR (qRT-PCR) were used to evaluate the expression of the genes. 【Result】 A total of 17 CsCNL genes were identified from cucumber genome. CsCNL genes are distributed on 6 chromosomes except chromosome 1. The encoded proteins are similar in structure to other plant CNLs. All CsCNL proteins contain conserved domains of CC, NBS and LRR. The amino acid sequence size ranged from 197 to 1 148 aa, with a molecular weight (MW) of 22.6 to 131.3 kD, and a protein isoelectric point (PI) ranged from 5.71 to 8.38. Collinear analysis showed that there were no segmental duplication and tandem duplication genes, and the multi-species phylogenetic relationship showed that CNL gene family members had high structural and functional similarities among Cucurbitaceae plants. There were many cis-acting elements related to disease resistance in the promoter of CsCNL genes. The expression of CsCNL genes was tissue-specific. At 2 d and 5 d after inoculation with P. cubensis, Csa3G815400, Csa3G822360 and Csa7G420890 were all significantly up-regulated in resistant variety, Csa4G015850 was down-regulated in resistant variety, and significantly different in susceptible variety. At 2 d and 5 d after P. xanthii inoculation, Csa2G008000 and Csa3G684170 were significantly up-regulated in susceptible variety and significantly down-regulated in resistant variety. Csa4G016360, Csa7G420890 and Csa7G425940 were significantly up-regulated in resistant variety, while unchanged or significantly down-regulated in susceptible variety. 【Conclusion】 CsCNL gene family has specific expression pattern in different tissues, and most of the CsCNL genes were induced by P. cubensis and P. xanthii. It is speculated that the increased expression of Csa3G815400, Csa3G822360 and Csa7G420890, and the decreased expression of Csa4G015850 can induce downy mildew resistance in resistant cucumber varieties. The increased expression of Csa4G016360, Csa7G420890 and Csa7G425940, and the decreased expression of Csa2G008000 and Csa3G684170 can induce the resistance to powdery mildew in resistant cucumber varieties, while the increased expression of Csa7G420890 can simultaneously induce disease resistance to downy mildew and powdery mildew in resistant cucumber varieties.

Key words: cucumber (Cucumis sativus), CC-NBS-LRR (CNL), downy mildew, powdery mildew, gene expression