ANALYSIS OF PEST INSECT RESPONSE IN CITRUS USING ARRAY TRANSCRIPT PROFILING.

¹ USDA, ARS, USHRL, 2001 South Rock Road, Fort Pierce, FL 34945

Collaborative research on the adaptation of genomic methods to fit the needs of non-model plant insect interactions among multiple insects and Citrus will be presented. High throughput sequence generation and analysis has been performed on both citrus and on several of the economically important insect pests of citrus. Transcript profiling of high-density cDNA arrays was used to study insect damage response in citrus leaf tissue and to compare damage responses to developmental changes as leaves age. This work showed that many transcripts that accumulated in response to insect attack also became more abundant when leaves matured: a time when the leaves became more insect resistant. Also, comparison of chewing and phloem-feeding insects showed that the type of insect that is feeding could be as important of a determinant of plant transcriptome response as is the mechanism of feeding. For example, as a gene family, metallothionein-like proteins were the most responsive transcripts, being upregulated in response to a chewing (Diaprepes root weevil) and a phloem-feeding (Asian citrus psyllid) insect attack; however, another phloem-feeding insect (Brown citrus aphid) stimulated a much smaller accumulation of this/these transcript(s). Our work shows, that genomics approaches to non-model systems can be powerful and feasible when appropriate multidisciplinary collaborations are developed to generate the necessary tools.