Characterization of Salt Overly Sensitive 1 (SOS1) gene homoeologs in quinoa (Chenopodium quinoa Willd.)

Abstract

Salt tolerance is an agronomically important trait that affects plant species around the globe. The Salt Overly Sensitive 1 (SOS1) gene encodes a plasma membrane Na+/H+ antiporter that plays an important role in germination and growth of plants in saline environments. Quinoa (Chenopodium quinoa Willd.) is a halophytic, allotetraploid grain crop of the family Amaranthaceae with impressive nutritional content and an increasing worldwide market. Many quinoa varieties have considerable salt tolerance, and research suggests quinoa may utilize novel mechanisms to confer salt tolerance. Here we report the cloning and characterization of two homoeologous SOS1 loci (cqSOS1A and cqSOS1B) from C. quinoa, including full-length cDNA sequences, genomic sequences, relative expression levels, fluorescent in situ hybridization (FISH) analysis, and a phylogenetic analysis of SOS1 genes from 13 plant taxa. The cqSOS1A and cqSOS1B genes each span 23 exons spread over 3477 bp and 3486 bp of coding sequence, respectively. These sequences share a high level of similarity with SOS1 homologs of other species and contain two conserved domains, a Nhap cation-antiporter domain and a cyclic-nucleotide binding domain. Genomic sequence analysis of two BAC clones (98 357 bp and 132 770 bp) containing the homoeologous SOS1 genes suggests possible conservation of synteny across the C. quinoa sub-genomes. This report represents the first molecular characterization of salt-tolerance genes in a halophytic species in the Amaranthaceae as well as the first comparative analysis of coding and non-coding DNA sequences of the two homoeologous genomes of C. quinoa.

Transcriptome Analysis of Drought Induced Stress in <i>Chenopodium quinoa</i>

“…Recent genomic research in quinoa has successfully identified genes (e.g., SOS1, NHX1, etc.) associated with salt tolerance [26,27], further suggesting the possibility of unraveling the genetic basis of drought resistance in quinoa through transcriptome analysis.…”

Role of Na+/H+Antiporters in Na+Homeostasis in Halophytic Plants

“…The SOS1 mRNA preferentially accumulates higher in roots compared to shoots. ThSOS1 transcript expression was found 7-fold higher in roots relative to shoots under salt stress [66], whereas in C. quinoa, CqSOS1 expression was high at low salt concentration in the root tissue, which indicates that the SOS1 gene is hyper-inducible in the roots of halophytic plants at even low salt concentrations [67]. Nitric oxide (NO) treatment showed higher expression of SOS1 in A. marina plants [69].…”

“…SOS1 gene expression was found upregulated by NaCl stress in shoots (Thellungiella [66], Chenopodium quinoa [67], Puccinellia tenuiflora [68]). The SOS1 mRNA preferentially accumulates higher in roots compared to shoots.…”

Plant Abiotic Stress: Insights from the Genomics Era

“…For example in halophytes, salt treatment of Thellungiella halophila led to increased expression of an AtSOS1 homologue in the plasma membrane and increased H+ transport and hydrolytic activity of the H+-ATPase was observed in both the plasma membrane as well the tonoplast (Vera-Estrella et al, 2005). Chenopodium quinoa, a halophyte native to the Andes Mountains, was found to contain 2 AtSOS1 homologs (Maughan et al, 2009), with future work to include complementation of a mutant sos1 Arabidopsis line with the homologues from C. quinoa. Homologues of AtSOS1 have also been identified for multiple glycophyte plant species such as rice (Oryza sativa), the seagrass Cymodocea nodosa, and Populus trichocarpa, the woody perennial poplar tree (Martínez-Atienza et al, 2007, Garciadeblás et al, 2007, Tang et al, 2007.…”