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

In addition to direct tissue consumption, herbivory may affect other important plant processes. Here, we evaluated the effects of short-time leaf feeding by Spodoptera exigua larvae on the photosynthetic efficiency of tomato plants, using chlorophyll a fluorescence imaging analysis. After 15 min of feeding, the light used for photochemistry at photosystem II (PSII) (ΦPSII), and the regulated heat loss at PSII (ΦNPQ) decreased locally at the feeding zones, accompanied by increased non-regulated energy losses (ΦNO) that indicated increased singlet oxygen (1O2) formation. In contrast, in zones neighboring the feeding zones and in the rest of the leaf, ΦPSII increased due to a decreased ΦNPQ. This suggests that leaf areas not directly affected by herbivory compensate for the photosynthetic losses by increasing the fraction of open PSII reaction centers (qp) and the efficiency of these centers (Fv’/Fm’), because of decreased non-photochemical quenching (NPQ). This compensatory reaction mechanism may be signaled by singlet oxygen formed at the feeding zone. PSII functionality at the feeding zones began to balance with the rest of the leaf 3 h after feeding, in parallel with decreased compensatory responses. Thus, 3 h after feeding, PSII efficiency at the whole-leaf level was the same as before feeding, indicating that the plant managed to overcome the feeding effects with no or minor photosynthetic costs.

Local adaptation to continuous mowing makes the noxious weed Solanum elaeagnifolium a superweed candidate by improving fitness and defense traits

The role of disturbance in accelerating weed growth is well understood. While most studies have focused on soil mediated disturbance, mowing can also impact weed traits. Using silverleaf nightshade (Solanum elaeagnifolium), a noxious and invasive weed, through a series of field, laboratory, and greenhouse experiments, we asked whether continuous mowing influences growth and plant defense traits, expressed via different avenues, and whether they cascade into offspring. We found that mowed plants produced significantly less number of fruits, and less number of total seeds per plant, but had higher seed mass, and germinated more and faster. When three herbivores were allowed to feed, tobacco hornworm (Manduca sexta) caterpillars, gained more mass on seedlings from unmowed plants, while cow pea aphid (Aphis craccivora), a generalist, established better on mowed seedlings; however, leaf trichome density was higher on unmowed seedlings, suggesting possible negative cross talk in defense traits. Texas potato beetle (Leptinotarsa texana), a co-evolved specialist on S. elaeagnifolium, did not show any differential feeding effects. We also found that specific root length, an indicator of nutrient acquisition, was significantly higher in first generation seedlings from mowed plants. Taken together, we show that mowing is a selective pressure that enhances some fitness and defense traits and can contribute to producing superweeds.

Percutaneous endoscopic gastrostomy feeding effects in patients with neurogenic dysphagia and recurrent pneumonia

Background: Percutaneous endoscopic gastrostomy (PEG) feeding provides enteral nutrition to patients with neurological dysphagia. However, the conditions in which PEG should be applied to prevent pneumonia remain unclear. We aimed to evaluate the effect of PEG for patients with neurological dysphagia in preventing pneumonia. Methods: We undertook a retrospective data review of 232 patients with neurological dysphagia who had undergone PEG from January 2008 to December 2018 at Inha University Hospital, in Incheon, Korea. We excluded patients who had not been followed up 6 months pre- and post-PEG feeding. In total, our study comprised 42 patients. We compared pneumonia episodes and incidence pre- and post-PEG. Results: During the median post-PEG follow-up period, the 6-month pneumonia incidence among patients who had undergone PEG had decreased [median 0.3 (interquartile range (IQR) 0.0–0.7) versus 0.1 (IQR 0.1–0.3) episodes, p = 0.04]. In a multiple mixed model, PEG did not decrease the incidence of pneumonia ( p = 0.76). However, the association between PEG and the incidence of pneumonia differed significantly depending on the presence or absence of recurrent pneumonia ( p < 0.001). Conclusions: PEG could effectively reduce the incidence of pneumonia in patients with neurogenic dysphagia, especially in those who had experienced recurrent pneumonia. The reviews of this paper are available via the supplemental material section.