Regulation of callose synthases and beta-1,3-glucanases during aphid infestation on barley cv. Clipper

Abstract: Plant resistance hypothesis says that under a period of time when a plant is exposed to powerful herbivore attack it will prioritise defence as a major metabolic function. In theory, induced plant defence (resistance) will provide opportunities for this organism to “invest” in other functions, in example growth when attackers are absent. One of the compounds taking part in plant defence is callose. This β-1,3-glucan is synthesised by callose synthase and broken down by β-1,3-glucanase. Deposition of callose occurs as a reaction to aphid attack an varies, depending on cultivars, and aphid species. In this experiment barley (Hordeum vulgare) cultivar Clipper is being infested with two types of aphids: Russian wheat aphid (RWA, Diuraphis noxia) and bird cherry-oat aphid (BCA, Rhopalosiphium padi) over a time period. Infestation by those two insects results in different callose formation and deposition level. Six sequences encoding for putative callose synthase genes and nine sequences encoding for β-1,3-glucanase were examined by RT-PCR and Real – Time PCR methods for different expression patterns. The results did not show any significant regulation of gene expression during RWA and BCA attack for any of these genes. Thus the pathway regulating aphid – induced callose deposition in barley reminds unresolved.