Identification of the Chenopodium quinoa HSP90 Gene Family and Functional Analysis of CqHSP90.1c and CqHSP90.6a Under High-Temperature Stress in Transgenic Arabidopsis thaliana

Heat shock protein 90 (HSP90) is an evolutionarily conserved molecular chaperone. Numerous studies have shown that it is widely involved in protein folding, assembly, stabilization, activation, and degradation in response to various biotic and abiotic stresses in many normal cellular processes and under stress conditions. We identified 11 members of the <i>CqHSP90</i> gene family in the quinoa (<i>Chenopodium quinoa</i>) genome by bioinformatics analysis. Phylogenetic tree analysis showed that quinoa was more closely related to dicotyledonous plants than to monocotyledonous plants. Quinoa is susceptible to high-temperature stress during its growth and development. We analyzed the cis-acting elements of its promoter, and found that nearly 1/3 of the cis-acting elements were stress-responsive, and 2/3 of them had heat-responsive elements. The results of qRT-PCR showed that heat shock at 40 °C could induce a high expression of <i>CqHSP90.1c</i> and <i>CqHSP90.6a</i>. Subcellular localization indicates that they are all membrane proteins. At the same time, both <i>CqHSP90.1c</i> and <i>CqHSP90.6a</i> overexpression lines improved the tolerance of <i>Arabidopsis thaliana</i> under high temperature, indicating that both of them had a positive regulatory effect under heat stress. Results of this study could provide useful information for further study on the biological role of <i>CqHSP90.1c</i> and <i>CqHSP90.6a</i>, and provide theoretical basis for quinoa resistance breeding.