Changes in Light Energy Utilization in Photosystem II and Reactive Oxygen Species Generation in Potato Leaves by the Pinworm Tuta absoluta

Abstract

We evaluated photosystem II (PSII) functionality in potato plants (Solanum tuberosum L.) before and after a 15 min feeding by the leaf miner Tuta absoluta using chlorophyll a fluorescence imaging analysis combined with reactive oxygen species (ROS) detection. Fifteen minutes after feeding, we observed at the feeding zone and at the whole leaf a decrease in the effective quantum yield of photosystem II (PSII) photochemistry (ΦPSII). While at the feeding zone the quantum yield of regulated non-photochemical energy loss in PSII (ΦNPQ) did not change, at the whole leaf level there was a significant increase. As a result, at the feeding zone a significant increase in the quantum yield of non-regulated energy loss in PSII (ΦNO) occurred, but there was no change at the whole leaf level compared to that before feeding, indicating no change in singlet oxygen (1O2) formation. The decreased ΦPSII after feeding was due to a decreased fraction of open reaction centers (qp), since the efficiency of open PSII reaction centers to utilize the light energy (Fv′/Fm′) did not differ before and after feeding. The decreased fraction of open reaction centers resulted in increased excess excitation energy (EXC) at the feeding zone and at the whole leaf level, while hydrogen peroxide (H2O2) production was detected only at the feeding zone. Although the whole leaf PSII efficiency decreased compared to that before feeding, the maximum efficiency of PSII photochemistry (Fv/Fm), and the efficiency of the water-splitting complex on the donor side of PSII (Fv/Fo), did not differ to that before feeding, thus they cannot be considered as sensitive parameters to monitor biotic stress effects. Chlorophyll fluorescence imaging analysis proved to be a good indicator to monitor even short-term impacts of insect herbivory on photosynthetic function, and among the studied parameters, the reduction status of the plastoquinone pool (qp) was the most sensitive and suitable indicator to probe photosynthetic function under biotic stress.

Induction of a Compensatory Photosynthetic Response Mechanism in Tomato Leaves upon Short Time Feeding by the Chewing Insect Spodoptera exigua

“…These contradictory results can be due to different experimental strategies, including differentially time-scheduled spatiotemporal measurements [ 4 , 5 , 6 ] and/or to the lack of spatiotemporal measurements [ 7 , 8 , 9 ]. In addition, increased NPQ at the whole leaf level is considered a major component of the systemic acquired resistance in many photosynthetic species-specific responses to insect herbivory [ 89 ]. Due to global climate change, elevated average temperatures are expected to influence plant–insect interactions and increase crop damage for two reasons [ 90 ].…”

Leaf Age-Dependent Photosystem II Photochemistry and Oxidative Stress Responses to Drought Stress in Arabidopsis thaliana Are Modulated by Flavonoid Accumulation

“…Under most environmental stresses, the absorbed light energy exceeds what it can be used, resulting in ROS generation, such as superoxide anion radical (O 2 • − ), hydrogen peroxide (H 2 O 2 ) and 1 O 2 [ 38 , 41 , 61 , 62 , 63 , 64 , 65 , 66 ]. When ROS production is not counterbalanced by the antioxidant defense network, photo-oxidative stress occurs [ 24 , 41 , 61 , 62 ].…”

“…When ROS production is not counterbalanced by the antioxidant defense network, photo-oxidative stress occurs [ 24 , 41 , 61 , 62 ]. ROS–antioxidant interaction provides important knowledge for the redox state that impacts gene expression associated with plant stress responses modulating the initiation of photosynthetic acclimation or cell death [ 66 , 67 , 68 , 69 , 70 ].…”

“…However, ROS produced in chloroplasts are not only creating oxidative stress but also confer significant biological functions, such as redox signaling in the regulation of leaf development and translating information from the environment [ 69 , 70 , 74 , 80 , 81 , 82 ]. NPQ has also been suggested to be involved in the mechanism of plant acclimation to biotic or abiotic stress and to be a major component of the systemic acquired resistance [ 66 , 70 , 83 , 84 , 85 , 86 ].…”

“…Chlorophyll fluorescence analysis has been widely used to acquire knowledge about the function of the photosynthetic machinery and for the assessment of photosynthetic tolerance mechanisms to biotic [ 66 , 86 , 101 , 102 ] and abiotic stresses [ 103 , 104 , 105 , 106 , 107 , 108 ], including drought stress [ 21 , 22 , 96 , 108 , 109 , 110 ]. However, DS may not affect a plant leaf uniformly [ 97 ], thus photosynthetic performance may be extremely heterogeneous at the leaf surface, denoting conventional chlorophyll fluorescence measurements non-characteristic of the physiological status of the entire leaf [ 111 , 112 , 113 ].…”