Identification of CDK gene family and functional analysis of CqCDK15 under drought and salt stress in quinoa

Abstract as one of the oldest cultivated crops in the world, quinoa has been widely valued for its rich nutritional value and green health. In this study, 22 CDK genes ( CqCDK01-CqCDK22 ) were identified from quinoa genome using bioinformatics method. The number of amino acids was 173–811, the molecular weight was 19,554.89 Da-91,375.70 Da, and the isoelectric point was 4.57–9.77. The phylogenetic tree divided 21 CqCDK genes into six subfamilies, the gene structure showed that 12 (54.5%) CqCDK genes ( CqCDK03 , CqCDK04 , CqCDK05 , CqCDK06 , CqCDK07 , CqCDK11 , CqCDK14 , CqCDK16 , CqCDK18 , CqCDK19 , CqCDK20 and CqCDK21 ) had UTR regions at 5’ and 3’ ends. Each CDK protein had different motifs (3–9 motifs), but the genes with the same motifs were located in the same branch. Promoter analysis revealed 41 cis-regulatory elements related to plant hormones, abiotic stresses, tissue-specific expression and photoresponse. The results of real-time fluorescence quantitative analysis showed that the expression level of some CDK genes was higher under drought and salt stress, which indicated that CDK genes could help plants to resist adverse environmental effects. Subcellular localization showed that CqCDK15 gene was localized to the nucleus and cytoplasm, and transgenic plants overexpressing CqCDK15 gene showed higher drought and salt tolerance compared to the controls. Therefore, CDK genes are closely related to quinoa stress resistance. In this study, the main functions of quinoa CDK gene family and its expression level in different tissues and organs were analyzed in detail, which provided some theoretical support for quinoa stress-resistant breeding. Meanwhile, this study has important implications for further understanding the function of the CDK gene family in quinoa and our understanding of the CDK family in vascular plant.