Abstract:

The WRKYs are important plant transcription factors， which regulate growth and development， and responses to various stresses in plants. The aim of the research was to elucidate evolutionary links and explore ways to exploit the stress responsive members of the WRKY gene family in Chenopodium quinoa. Systematic bioinformatics methods were used to identify the genome-wide occurrence of WRKY genes in C. quinoa， determine their chromosomal location， classification and systematic evolutionary affinities， conduct synteny analysis and measure expression profiles under different stresses. In total， 90 WRKY genes were identified in the genome of C. quinoa. These were classified as group Ⅰ （18 members）， group Ⅱ （46） and group Ⅲ （12）. Fourteen WRKY family members could not be assigned to a group due to the lack of WRKYGQK peptide and dramatic variation of the zinc finger. The members of group Ⅱ were further assigned to five subgroups： Ⅱ-a （9）， Ⅱ-b （4）， Ⅱ-c （13）， Ⅱ-d （10） and Ⅱ-e （10）. A compiled phylogenetic tree identified WRKY gene clusters that were consistent with the WRKY gene classification， further supporting the accuracy of our classification of WRKY member genes. Additionally， the protein sequences of WRKY member genes from different groups revealed group-specific conserved domains. The syntenic genomic regions between C. quinoa， Chenopodium pallidicaule and Chenopodium suecicum demonstrated that the WRKY gene expansion in C. quinoa resulted from the whole genome duplication of C. quinoa. Under drought， heat， salt and low P， and groundnut chlorotic fan-spot virus （GCFSV） infection stresses， the expression levels of a number of WRKY genes were significantly down- or up-regulated， implying these WRKY genes participate in regulating the responses to these biotic and abiotic stresses. Our results indicate good gene candidates and provide reference information for future studies of stress tolerance in C. quinoa.

Key words: Chenopodium quinoa, WRKY, evolution, stress, transcriptional response