Plant jasmonoyl-L-isoleucine(JA-Ile)is a major defense signal against insect feeding,but whether or how insect salivary effectors suppress JA-Ile synthesis and thus facilitate viral transmission in the plant phloem re...Plant jasmonoyl-L-isoleucine(JA-Ile)is a major defense signal against insect feeding,but whether or how insect salivary effectors suppress JA-Ile synthesis and thus facilitate viral transmission in the plant phloem remains elusive.Insect carboxylesterases(CarEs)are the third major family of detoxification enzymes.Here,we identify a new leafhopper CarE,CarE10,that is specifically expressed in salivary glands and is secreted into the rice phloem as a saliva component.Leafhopper CarE10 directly binds to rice jasmonate resistant 1(JAR1)and promotes its degradation by the proteasome system.Moreover,the direct association of CarE10 with JAR1 clearly impairs JAR1 enzyme activity for conversion of JA to JA-Ile in an in vitro JAIle synthesis system.A devastating rice reovirus activates and promotes the co-secretion of virions and CarE10 via virus-induced vesicles into the saliva-storing salivary cavities of the leafhopper vector and ultimately into the rice phloem to establish initial infection.Furthermore,a virus-mediated increase in CarE10 secretion or overexpression of CarE10 in transgenic rice plants causes reduced levels of JAR1 and thus suppresses JA-Ile synthesis,promoting host attractiveness to insect vectors and facilitating initial viral transmission.Our findings provide insight into how the insect salivary protein CarE10 suppresses host JA-Ile synthesis to promote initial virus transmission in the rice phloem.展开更多
基金supported by the National Key Research and Development Program of China(2023YFD1400300)the Natural Science Foundation of Fujian Province(2021J01065 and 2022J01127)the National Natural Science Foundation of China(nos.61831920103014 and 32202270).
文摘Plant jasmonoyl-L-isoleucine(JA-Ile)is a major defense signal against insect feeding,but whether or how insect salivary effectors suppress JA-Ile synthesis and thus facilitate viral transmission in the plant phloem remains elusive.Insect carboxylesterases(CarEs)are the third major family of detoxification enzymes.Here,we identify a new leafhopper CarE,CarE10,that is specifically expressed in salivary glands and is secreted into the rice phloem as a saliva component.Leafhopper CarE10 directly binds to rice jasmonate resistant 1(JAR1)and promotes its degradation by the proteasome system.Moreover,the direct association of CarE10 with JAR1 clearly impairs JAR1 enzyme activity for conversion of JA to JA-Ile in an in vitro JAIle synthesis system.A devastating rice reovirus activates and promotes the co-secretion of virions and CarE10 via virus-induced vesicles into the saliva-storing salivary cavities of the leafhopper vector and ultimately into the rice phloem to establish initial infection.Furthermore,a virus-mediated increase in CarE10 secretion or overexpression of CarE10 in transgenic rice plants causes reduced levels of JAR1 and thus suppresses JA-Ile synthesis,promoting host attractiveness to insect vectors and facilitating initial viral transmission.Our findings provide insight into how the insect salivary protein CarE10 suppresses host JA-Ile synthesis to promote initial virus transmission in the rice phloem.
