Transcriptome analyses of quinoa leaves revealed critical function of epidermal bladder cells in salt stress acclimation

The ability of some halophytic plants such as Chenopodium quinoa to sequester large quantities of salt into epidermal bladder cell (EBC) is considered as one of the traits conferring their salinity stress resilience. In the current study, we used mRNA-seq to characterize transcriptome differences between intact and EBC-free quinoa leaves from plants that were treated with 400 mM NaCl for 4 weeks. Employing K-means clustering on differentially expressed genes identified clusters of genes showing distinct expression patterns, indicating significant differences between quinoa leaves with or without EBCs in response to salt stress. EBC-free leaves retained most transcriptome responses to salt stress as normal intact leaves. However, specific processes such as increased DNA replication activity failed to be induced in EBC-free leaves. This correlated with reduced expression of many immune response-related genes and increased expression of multiple phytohormone signaling components. These results revealed that EBCs play a critical role in salt stress acclimation of quinoa leaves and provided important candidate genes for further mechanistic studies.