Structural Damage in the Vascular Tissues of Resistant and Non-Resistant Barley (Hordeum Vulgare L.) by Two South African Biotypes of the Russian Wheat Aphid

Abstract

The effects of the structural damage caused by the two South African biotypes of the Russian wheat aphid (RWA, Diuraphis noxia Kurdjumov), RWASA1 and RWASA2, through formation and distribution of wound callose in the phloem tissues of non-resistant and resistant barley (Hordeum vulgare L.) cultivars were investigated. Our results revealed that RWASA2 breeds faster than RWASA1 and both cause the deposition of feeding induce wound callose in the phloem tissue within 24h of infestation on both resistant and non-resistant barley lines, but the deposition was higher in the former than the latter. This wound callose deposition became more extensive and
pronounced with sustained feeding exposure of 3, 7 and 14 days, yet, it is more extensive in the non-resistant than in the resistant plants. The reduction in the amount of wound callose found in the veins of the resistant plants indicates that the resistance gene in them may have mitigated the effects of feeding by the two RWA biotypes. It is suggested that the resistant lines should be studied further to unravel the mechanism behind the seemingly differences in their responses to infestation by the two biotypes, in the endeavour to develop RWA-resistant barley lines.