AUTHOR=Jiang Wei , Li Chao , Li Leiting , Li Yali , Wang Zhihao , Yu Feiyu , Yi Feng , Zhang Jianhan , Zhu Jian-Kang , Zhang Heng , Li Yan , Zhao Chunzhao 

TITLE=Genome-Wide Analysis of CqCrRLK1L and CqRALF Gene Families in Chenopodium quinoa and Their Roles in Salt Stress Response

JOURNAL=Frontiers in Plant Science

VOLUME=13

YEAR=2022

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2022.918594

DOI=10.3389/fpls.2022.918594

ISSN=1664-462X

ABSTRACT=<p><italic>Chenopodium quinoa</italic> is a halophyte with exceptional nutritional qualities, and therefore it is potentially an ideal crop to grow in saline soils, not only addressing the problem of land salinization, but also providing nutrient food for the health of humans. Currently, the molecular mechanisms underlying salt tolerance in quinoa are still largely unknown. In <italic>Arabidopsis thaliana</italic>, <italic>Catharanthus roseus</italic> receptor-like kinase (<italic>Cr</italic>RLK1Ls) FERONIA (FER) and its ligands rapid alkalinization factors (RALFs) have been reported that participate in the regulation of salt tolerance. Here, we performed a genome-wide analysis and identified 26 <italic>CqCrRLK1L</italic> and 18 <italic>CqRALF</italic> family genes in quinoa genome. Transcriptomic profiling of the leaf, root, stamen, and pistil tissues of quinoa reveals that different <italic>CqCrRLK1L</italic> and <italic>CqRALF</italic> genes exhibit tissue-specific expression patterns, which is consistent with that observed in other plant species. RNA-seq data show that three <italic>CqCrRLK1L</italic> genes are highly up-regulated after salt treatment, suggesting that some <italic>CqCrRLK1L</italic> family genes are transcriptionally responsive to salt stress in quinoa. Biochemical study indicates that CqRALF15, a paralog of Arabidopsis RALF22, is physically associated with <italic>Cr</italic>RLK1L proteins CqFER and AtFER. CqRALF15 and AtRALF22 are functionally conserved in inducing the internalization of AtFER and in triggering root growth inhibition in both quinoa and Arabidopsis. Moreover, overexpression of <italic>CqRALF15</italic> in Arabidopsis results in enhanced leaf bleaching under salt stress, indicating that <italic>CqRALF15</italic> is involved in salt stress response. Together, our study characterizes <italic>CqCrRLK1L</italic> and <italic>CqRALF</italic> family genes in quinoa at genomic, transcriptional, and protein levels, and provides evidence to support their roles in salt stress response.</p>