Antisense-mediated suppression of C-hordein biosynthesis in the barley grain results in correlated changes in the transcriptome, protein profile, and amino acid composition

Antisense- or RNAi-mediated suppression of the biosynthesis of nutritionally inferior storage proteins is a promising strategy for improving the amino acid profile of seeds. However, the potential pleiotropic effects of this on interconnected pathways and the agronomic quality traits need to be addressed.

In the current study, a transcriptomic analysis of an antisense C-hordein line of barley was performed, using a grain-specific cDNA array. The C-hordein antisense line is characterized by marked changes in storage protein and amino acid profiles, while the seed weight is within the normal range and no external morphological irregularities were observed.

The results of the transcriptome analysis showed excellent correlation with data on changes in the relative proportions of storage proteins and amino acid composition. The antisense line had a lower C-hordein level and down-regulated transcript encoding C-hordein. The production of the S-rich B/gamma- and D-hordeins was increased and significantly higher steady-state expression levels of the corresponding genes were observed.

The increased synthesis of S-rich hordeins appeared to increase the demand for sulphur and the S-rich amino acids (cysteine and methionine), resulting in an up-regulation of key genes in the appropriate biosynthetic pathways. This study demonstrated the utility of the grain-specific cDNA microarray analysis to detect perturbations induced by antisense suppression of plant processes.