Abstract
The Asian citrus psyllid (ACP), Diaphorina citri Kuwayama, is the only natural vector of bacteria responsible for Huanglongbing (HLB), a worldwide destructive disease of citrus. ACP reproduces and develops only on the young leaves of its rutaceous host plants. Olfactory stimuli emitted by young leaves may play an important role in ACP control and HLB detection. In this study, volatile organic compounds (VOCs) from healthy and HLB-infected young leaves of navel orange and pomelo were analyzed by headspace-gas chromatography-ion mobility spectrometry (HS-GC-IMS). A total of 36 compounds (including dimers or polymers) were identified and quantified from orange and 10 from pomelo leaves. Some compounds showed significant differences in signal intensity between healthy and HLB-infected leaves and may constitute possible indicators for HLB infection. Principal component analysis (PCA) clearly discriminated healthy and HLB-infected leaves in both orange and pomelo. HS-GC-IMS was an effective method to identify VOCs from leaves. This study may help develop new methods for detection of HLB or find new attractants or repellents of ACP for prevention of HLB.
Highlights
Huanglongbing (HLB), known as citrus greening disease, is a worldwide destructive disease of citrus [1]
As plant leaves are a major source of volatile organic compounds (VOCs) emitted in the atmosphere and plant foliar VOCs are very important in mediating plant–plant and plant–insect communication, many methods and analytical techniques have been developed for plant foliar VOC research [31]
Comparison of VOCs in navel orange and pomelo healthy and HLB-infected young leaves would be helpful to understand the role of VOCs played in the host plant of Asian citrus psyllid (ACP), which may be beneficial in designing ACP control strategies, as well as HLB detection
Summary
Huanglongbing (HLB), known as citrus greening disease, is a worldwide destructive disease of citrus [1]. The Asian citrus psyllid (ACP), Diaphorina citri Kuwayama, is the only vector of bacteria responsible for HLB [5]. Novel and sustainable approaches to the control of ACP are urgently needed for successful HLB management programs. ACP mates, oviposits, and develops exclusively on new flush shoots [6]. Recent studies have shown that volatile organic compounds (VOCs) emitted by flushing shoots may play an important role in the detection, location, and evaluation of potential host plants by ACP [7]. The ability to understand the chemical composition of citrus leaf VOCs may facilitate ACP’s ability to recognize the stimuli signal from its host plant and the interaction between them. Wenninger et al demonstrated that ACP used olfactory cues in orientation to host plants and suggested using plant VOCs to monitor and Molecules 2020, 25, 4119; doi:10.3390/molecules25184119 www.mdpi.com/journal/molecules
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