|
Résumé :
|
A resistant barley (Hordeum vulgare L., PI 366450) was used to compare physiological responses of a susceptible barley ('Morex') to the recently introduced pest, Russian wheat aphid, Diuraphis noxia (Mordvilko). As measured by chlorosis, leaf rolling, and streaking, damage by Russian wheat aphid was greater in 'Morex' than in PI 366450. The inhibition of growth, as measured by plant height, shoot dry weight, and number of leaves, also was greater in 'Morex' than in PI 366450. Relative water contents of leaves or stems showed no differences between 'Morex' and PI 366450 as a result of infestation. Well-watered PI 366450 showed greater stomatal closure in response to aphid infestation than 'Morex'. However, the stomatal resistance responses of water-deprived PI 366450 and 'Morex' to Russian wheat aphids could not be distinguished. The two-dimensional SDS-PAGE protein profiles of uninfested 'Morex' and PI 366450 leaves were virtually identical. Upon infestation, a complex of proteins (almost-equal-to 23 k D) was altered in the PI 366450 profile and had decreased levels in 'Morex'. Chlorophyll measurements indicated a greater relative loss of chlorophyll during infestation in 'Morex' than in PI 366450 when deprived of water; no differences could be distinguished when well watered. Measurements of the effectiveness of photosystem II to transfer electrons also showed no differences between well-watered resistant and susceptible barleys as a result of aphid infestation. However, the ability of the quinone pool in 'Morex' to recover after illumination was reduced greatly relative to that of PI 366450.
|
