Singlet oxygen in signaling for aphid resistance in Arabidopsis

Singlet oxygen (¹O₂) is an overlooked reactive oxygen species as a signaling molecule for host-plant resistance to aphids. Because ¹O₂ is highly reactive, with a half-life of ~200ns, it can be difficult to study. This project aimed to determine if ¹O₂ production increases due to Myzus persicae infestation,  and if ¹O₂-signaling impacts aphid fitness, specifically through the EXECUTER1/2 signaling pathway. A luciferase-based reporter gene that is selectively stimulated by ¹O₂ was used to compare¹O₂ accumulation in infested and uninfested Arabidopsis. Results indicated that ¹O₂ levels were significantly higher in infested plants compared to uninifested controls 24h after infestation. In addition, the conditional flu mutant in Arabidopsis, which accumulates excess ¹O₂ when it is transferred from light to dark and back to light again (L:D:L shift), was used to test the effects of ¹O₂ on Myzus persicae infestations. When flu was grown in continuous light and did not accumulate excess ¹O₂, aphid population growth was comparable on flu and wild-type plants. In contrast, when the plants were exposed to a L:D:L shift, flu accumulated higher ¹O₂ than WT plants, and supported significantly fewer aphids. Furthermore, plants with the ex1/ex2 mutations, that are insensitive to ¹O₂ signaling, in the flu background did not have significantly lower aphid production. These results suggest that ¹O₂ may contribute to plant defenses against aphids.