Dynamic change in photosynthetic pigments and chlorophyll degradation elicited by cereal aphid feeding

Abstract

The concentration of photosynthetic pigments (i.e., chlorophylls a and b, and carotenoids) and chlorophyll degradation enzyme (i.e., chlorophyllase, oxidative bleaching, and Mg‐dechelatase) activities on aphid‐damaged and non‐damaged regions of the infested leaves were determined with two infestation periods (6 and 12 days). Russian wheat aphid [Diuraphis noxia (Mordvilko) (Hemiptera: Aphididae)] feeding caused significant losses of chlorophylls a and b and carotenoids in the damaged regions. However, bird cherry‐oat aphid [Rhopalosiphum padi (L.) (Hemiptera: Aphididae)] feeding did not, except a significantly lower level of carotenoids was observed in the damaged regions from the short‐infestation (6‐day) samples. Interestingly, the non‐damaged regions of D. noxia‐infested leaves on both sampling dates had a significant increase of chlorophylls a and b and carotenoid concentrations when compared with the uninfested leaves. Although D. noxia feeding did not cause any changes in either chlorophyll a/b or chlorophyll (a+b)/carotenoid ratio between the damaged and non‐damaged leaf regions on short‐infestation (6‐day) samples, a significantly lower chlorophyll a/b ratio was detected in long‐infestation (12‐day) samples. The assays of chlorophyllase and oxidative bleaching activities showed no significant differences between the damaged and non‐damaged regions of the infested leaves on either sampling date. Mg‐dechelatase activity, however, was significantly higher in D. noxia‐damaged than non‐damaged leaf regions from the short‐infestation samples, while no differences were detected from the long‐infestation samples. Furthermore, the long‐infestation samples showed that Mg‐dechelatase activity from both D. noxia‐damaged and non‐damaged regions increased significantly in comparison with the respective regions of either uninfested or R. padi‐infested leaves. We infer that non‐damaged regions of D. noxia‐infested leaves compensate for the pigment losses in the damaged regions, and that Mg‐dechelatase activity changed dynamically from a localized response to a systemic response as infestation duration extends. The findings from this study on cereal aphid‐elicited chlorosis (or desistance) would help us to elucidate plant resistance mechanisms, in particular plant tolerance to non‐defoliating herbivory.

Differential photosynthetic performance of three Mediterranean shrubs under grazing by domestic goats

“…In contrast, the decrease in pigment concentrations recorded for grazed plants of M. communis in July did not lead to a significant decline in the photochemistry of PSII of these species. Ni et al (2002) also found significant loss of chlorophylls and carotenoids as a result of Russian wheat aphid infestation, mediated by increased Mg-dechelatase activity.…”

Changes in carotenoid content and distribution in living plant tissue can be observed and mapped in situ using NIR-FT-Raman spectroscopy

“…However, Fleischmann et al (2004) have recently found that the content of xanthophyll-cycle carotenoids significantly increased in Phytophtora citricola-infected leaves of Fagus sylvatica. It has been also reported that aphids feeding on wheat leaves stimulated the carotenoid accumulation (Ni et al 2002). To our knowledge, there is no information available on biochemical mechanism of Septoria petroselini invasion and therefore the nature of the observed phenomenon of carotenoid accumulation is to be further investigated.…”

Impact of scale insect infestation on the content of photosynthetic pigments and chlorophyll fluorescence in two host plant species

“…The chlorophyll content in plant tissue is one of the primary parameters involved in the interactions between host plants and insects. Chlorophyll levels change during plant development, and nutritional deficiencies occur in response to a wide variety of stresses including biotic stresses such as insect feeding and pathogen infections (Ni et al 2001(Ni et al , 2002Heng-Moss et al 2003;Goławska et al 2010). These changes can be helpful for investigating plants' resistance mechanisms and allow exploration of using photosynthetic pigments as markers for identifying different kinds of chlorosis-causing insects.…”