Future climate CO can harness ROS homeostasis and improve cell wall fortification to alleviate the hazardous effect of Phelipanche infection in pea seedlings.

Parasitic weeds such as Phelipanche aegyptiaca pose one of the most significant environmental constraints to cropping systems worldwide. The influence of P. aegyptiaca upon host plants is well studied, nevertheless, how future climate CO (eCO) can affect P. aegyptiaca parasite-host interactions is not yet investigated. Considering the protective effect of eCO, we studied its ability to mitigate the severity of P. aegyptiaca infection in pea plants (Pisum sativum). Our results revealed that Phelipanche infection strikingly reduced pea growth and photosynthesis. Moreover, infection with Phelipanche greatly burst the oxidative damage in pea plants by elevating photorespiration and NADPH oxidase activity. Contradictory, eCO extremely quenched the severity of P. aegyptiaca infection by diminishing the number and biomass of P. aegyptiaca tubercles. Additionally, eCO considerably mitigated the physiological and biochemical alterations exerted by Phelipanche upon pea seedlings. Within the physiological range, eCO augmented photosynthesis, that consequentially affected carbohydrate metabolism. Moreover, eCO highly mitigated the infection menace via quenching ROS overaccumulation which, sequentially reduced oxidative damage in infected pea plants. More interestingly, eCO improved cell wall fortification by enhancing lignin accumulation that considers the first line of defense against parasite penetration. Overall, this study concluded that pea plants grown in an atmosphere enriched with CO can efficiently cope with P. aegyptiaca infection via reducing Phelipanche tubercles, modulating ROS homeostasis, and enhancing cell wall fortification.