1H NMR analysis of Citrus macrophylla subjected to Asian citrus psyllid (Diaphorina citri Kuwayama) feeding
The Asian citrus psyllid (ACP) is a phloem-feeding insect that can host and transmit the bacterium Candidatus Liberibacter asiaticus (CLas), which is the putative causative agent of the economically important citrus disease, Huanglongbing (HLB). ACP are widespread in Florida, and are spreading in California; they are the primary mode of CLas transmission in citrus groves. To understand the effects of ACP feeding, different numbers of ACP [0 ACP (control), 5 ACP (low), 15–20 ACP (medium), and 25–30 ACP (high)] were allowed to feed on Citrus macrophylla greenhouse plants. After 7 days of feeding, leaves were collected and analyzed using 1H NMR. Metabolite concentrations from leaves of trees with ACP feeding had higher variability than control trees. Many metabolites were higher in concentration in the low ACP feeding group relative to control; however, leaves from trees with high ACP feeding had lower concentrations of many metabolites relative to control, including many amino acids such as phenylalanine, arginine, isoleucine, valine, threonine, and leucine. These results suggest ACP density-dependent changes in primary metabolism that can be measured by 1H NMR. The implications in plant defense are discussed.
KeywordsHuanglongbing (HLB) Asian citrus psyllid (ACP) Candidatus Liberibacter asiaticus (CLas)
The authors gratefully acknowledge support for this project from the Citrus Research Board. This project was made possible in part by support from the USDA National Institute of Food and Agriculture Hatch Project 1005945. We thank Steve Stearns for assistance with sample preparation, Dr. Cythia LeVesque for performing qPCR on the ACP colonies, Drs. Michelle Cilia, John Ramsey, and Greg McCollum for their suggestions and critical reading of the manuscript.
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