Characterization and absolute quantification of the Cellulose synthase-like F6 homoeologs in oats

The Cellulose synthase-like F6 (CslF6) gene has been reported as a key factor for β-glucan synthesis in grasses. However, the action of this gene on oat β-glucan content is poorly understood. The objectives of this study were: (i) to quantify the absolute expression of CslF6 transcripts in oats under field conditions; and (ii) to characterize the CslF6 homoeologs in oat genotypes with different levels of β-glucan content. Developing kernels of five oat genotypes were collected under field conditions in two planting dates. The CslF6 absolute quantification was performed using droplet digital PCR considering global and homoeolog-specific expressions. The third exon of the CslF6 gene, which covers approximately 62.2% of the coding region, was sequenced in each homoeolog. The CslF6 expression was highly influenced by planting date, kernel developmental stage, and genotype. High CslF6 transcript number was not associated with high β-glucan content, indicating the action of a complex biosynthesis pathway controlling this trait in oats. Under stressful conditions, the CslF6 expression was more pronounced and associated with β-glucan content. The CslF6 motif has 1767 bases pair and is highly conserved between A and D homoeologs. Single nucleotide polymorphisms were not identified among the assessed genotypes, regardless of the homoeolog. The results presented in this study may contribute for a better understanding of the CslF6 influence on oat β-glucan content.