Comparison of structural damage caused by Russian wheat aphid (Diuraphis noxia Mordvilko) and Bird cherry-oat aphid (Rhopalosiphum padi L.) in a susceptible barley cultivar, Hordeum vulgare L. cv Clipper.

Saheed, S. A. and Botha, C.E.J. and Liu, L. and Jonsson, L.M.V. (2007) Comparison of structural damage caused by Russian wheat aphid (Diuraphis noxia Mordvilko) and Bird cherry-oat aphid (Rhopalosiphum padi L.) in a susceptible barley cultivar, Hordeum vulgare L. cv Clipper. Physiologia Plantarum, 129 . pp. 429-435. ISSN 0031-9317

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Official URL: http://dx.doi.org/10.1111/j.1399-3054.2006.00821.x

Abstract

The Russian wheat aphid (RWA, (Diuraphis noxia Mordvilko) and the Bird cherry-oat aphid (BCA, (Rhopalosiphum padi L.) cause severe damage to grain crops, including barley. An investigation of the effects of these aphids on a susceptible cultivar revealed that BCA-infested barley plants remained healthy-looking for two weeks after feeding commenced. In contrast, signs of stress and damage, including chlorosis and leaf necrosis were evident in RWA infested plants. Our study suggests that damage to the vascular tissue due to sustained feeding by BCA, was not as extensive as that caused by RWA. In addition, there is a marked difference in the salivary secretion pattern within xylem elements punctured by aphids tapping the xylem for water. RWA deposit electron-dense, amorphous to smooth saliva, which completely encases the inner walls of affected elements, and saliva encases pit membranes between xylem elements, and between xylem vessels and xylem parenchyma. Xylem tapped by BCA, contained more granular saliva, which apparently does not occlude vessel wall apertures or the pit membranes to the same extent as was observed with RWA. Damage to phloem tissue, including phloem parenchyma elements, sieve tube-companion cell (CC-ST) complexes as well as thick-walled sieve tubes, was extensive. Plasmodesmata between phloem parenchyma elements as well as pore-plasmodesmata between the CC-ST were occluded by callose. We conclude that severe, perhaps permanent damage to conducting elements in RWA infested leaves may be responsible for the detrimental chlorosis and necrosis symptoms. These symptoms are absent in BCA-infested plants.

Item Type:Article
Additional Information:The definitive version is available at www.blackwell-synergy.com
Uncontrolled Keywords:Russian wheat aphid, RWA, Diuraphis noxia Mordvilko, Bird cherry-oat aphid, BCA, Rhopalosiphum padi L., ultrastructural damage, barley, Hordeum vulgare L. var Clipper, aphid saliva
Subjects:Y Unknown > Subjects to be assigned
Divisions:Faculty > Faculty of Science > Botany
ID Code:678
Deposited By: Ms Vivien Botha
Deposited On:05 Jun 2007
Last Modified:01 Aug 2012 10:38
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