AUTHOR=Ling Siquan , Rizvi Syed Arif Hussain , Xiong Ting , Liu Jiali , Gu Yanping , Wang Siwei , Zeng Xinnian 

TITLE=Volatile Signals From Guava Plants Prime Defense Signaling and Increase Jasmonate-Dependent Herbivore Resistance in Neighboring Citrus Plants

JOURNAL=Frontiers in Plant Science

VOLUME=Volume 13 - 2022

YEAR=2022

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2022.833562

DOI=10.3389/fpls.2022.833562

ISSN=1664-462X

ABSTRACT=Intercropping can reduce agricultural pest incidence and represents an important sustainable alternative to conventional pest control methods. Citrus intercropped with guava (Psidium guajava L.) has a lower incidence of Asian citrus psyllid (ACP, Diaphorina citri Kuwayama) and huanglongbing disease (HLB), but the mechanisms are still not well understood. In this study, whether volatile organic compounds (VOCs) emitted from guava plants play a role in plant–plant communications and trigger defense responses in sweet orange (Citrus sinensis (L.) Osbeck) was tested in the laboratory. The results showed that the behavioral preference and developmental performance of ACP on citrus plants that were exposed to guava VOCs were suppressed. The expression of defense-related pathways involved in early signaling, jasmonate (JA) biosynthesis, and protease inhibitor (PI), terpenoid, phenylpropanoid, and flavonoid biosynthesis was induced in guava VOC-exposed citrus plants. Headspace analysis showed that guava plants constitutively emit high levels of (E)-β-caryophyllene and (E)-4,8-dimethyl-1,3,7-nonatriene (DMNT), which can induce the accumulation of JA and promote stronger defense responses of citrus to ACP feeding. In addition, exposure to guava VOCs also increased the indirect defense of citrus by attracting the parasitic wasp Tamarixia radiata. Together, our findings indicate that citrus plants can eavesdrop on the VOC cues emitted from neighboring intact guava plants to boost their JA-dependent anti-herbivore activities. Knowledge from this study may lead to a mechanism of citrus-guava intercropping for the ecological management of insect pests.