Comparative transcriptomic, proteomic, and amino acid content analyses of quinoa (Chenopodium quinoa) seed accessions...

Quinoa (Chenopodium quinoa), a pseudocereal native to the Andean regions, is mainly characterized by the quality and nutritional value of its proteins due to an excellent balance of essential amino acids. To identify nutritional attributes and compare different germplasm accessions, we conducted comparative transcriptomic and proteomic studies on a total of five quinoa accessions. These include four accessions from different genetic groups representing dry valleys, dry highlands, transition areas, and humid valleys in the Northwest Argentina region (NWA), as well as QQ74, a sequenced Chilean coastal accession.

We analyzed the quinoa seed transcriptome of four different accessions by aligning the RNA-seq results with the second version of the QQ74 genome (QQ74-V2). After filtering and normalizing 29,355 transcripts, we observed that QQ74 was most distinct compared to NWA accessions. Subsequently, we performed a transcript differential analysis in the ten pairwise comparisons and identified a total of 3,014 differentially expressed genes (DEGs). A Gene Ontology (GO) enrichment analysis of these DEGs showed that the accession representing the NWA transition area was enriched in terms related to oxidative phosphorylation and heat response. Furthermore, using 2D-gel electrophoresis followed by mass spectrometry, we demonstrated that storage proteins, specifically 11S globulin, 13S globulin and vicilin-like antimicrobial peptides, were the most abundant proteins in quinoa seeds of the five accessions. In addition, we observed that some of these proteins were differentially expressed between accessions. In terms of total amino acid content, statistically significant differences between some of the accessions were found only for lysine and leucine.

The comparison of RNA-seq profiles among accessions grown in various geographical regions unveiled DEGs that could play a role in heat tolerance and plant development. These genes may contribute to the enhancement of quinoa through selective breeding processes.