CHANGES IN CHLOROPHYLL a FLUORESCENCE AND PIGMENTS COMPOSITION IN OAK LEAVES WITH GALLS OF TWO CYNIPID SPECIES (Hymenoptera, Cynipidae)

Abstract

Gall-inducing insects may cause multiple physiological changes in host plants, such as the loss of photosynthetic pigments and reduced photosynthetic capacity. However, the direction of these changes is usually insect species-dependent. Therefore, the objective of this research was to characterize the indirect effects of galls induced by asexual generation of Neuroterus numismalis (Fourc.) and N. quercusbaccarum L. on photosynthesis by comparing changes in photosynthetic and photoprotective pigments and chlorophyll a fluorescence in foliar tissue with and without galls in naturally growing pedunculate oak trees (Quercus robur L.). The presence of galls of both Cynipidae species caused a significant decrease of chlorophyll a, b and carotenoids contents. Moreover, photosynthetic parameters (F0, Fm, Fv/Fm, Y, qP, qN) were significantly decreased. These results provide valuable information for diagnosing the oak infections using a non-invasive method, such as chlorophyll a fluorescence and predicting the effect of infections on photosynthetic productivity.

Effect ofNeuroterus quercusbaccarum(L.) galls on physiological and biochemical response ofQuercus roburleaves

“…According to Dorchin et al (2006), gall-inducing species that feed on specialized nutritive tissues (e.g., cynipid wasps) cause less damage to surrounding tissues, thus it is more likely that assimilation rates will increase. However, other findings (Aldea et al, 2006;Kot et al, 2018b) and the results presented here showed no evidence to support this hypothesis. Galling process of N. quercusbaccarum on oaks leaves caused a decrease of the maximum quantum yield of photosystem II (F v /F m ), which characterizes the functional state of PSII in dark-adapted leaves.…”

“…Therefore, all fluorescence parameters mentioned above should also be analyzed (Huang et al ., 2013). In this study, a significant decrease of F m and F 0 values was observed, which proved, together with our previous study (Kot et al ., 2018 b ), that Cynipidae species that induce galls on leaves exerted a negative effect on photosynthetic rates. The occurrence of N. quercusbaccarum galls also resulted in a strong down-regulation of the effective quantum yield of photosystem II photochemistry ( Y ), i.e., the measure of the actual photochemical efficiency of PSII in illuminated leaves (Vassilev & Manolov, 1999).…”

“…The results of previous studies demonstrated that insect feeding had various effects on this parameter, depending on insect feeding modes or duration of infestation. For example, the presence of aphid galls (Kmieć et al ., 2018), midge galls (Nabity et al ., 2012), cynipid wasp galls (Kot et al ., 2018 b ) as well as aphids on barley (Gutsche et al ., 2009) caused a significant reduction of Y values. On the other hand, plants infested by scale insects showed increased (Retuerto et al ., 2004) or decreased (Kmieć et al ., 2016) values of this parameter.…”

Cynipid wasps systematically reprogram host metabolism and restructure cell walls in developing galls

“…It has been proposed that fatty acids are converted into sugars to feed the growing larva (Martinson et al, 2022). Finally, cynipid galls have previously been shown to contain lower concentrations of chlorophyll and carotenoids (Kot et al, 2018b;Kot et al, 2020), suggesting reduced photosynthesis as an explanation for the reduction in apocarotenoids observed here.…”

Comparative transcriptome reprogramming in oak galls containing asexual or sexual generations of gall wasps

“…The galls attached to leaves have a broader impact on the leaf to which it is attached. Leaves with galls exhibit reduced photosynthesis, chlorophyll, and carotenoid levels (Kot et al, 2018b, Kot et al, 2020). Additionally, there are increases in free radicals and defensive responses (Kot et al, 2018a, Kot and Rubinowska, 2018, Kot et al, 2019).…”