The Riptortus-Burkholderia symbiosis is a newly emerging insect-bacterium symbiotic system. This symbiosis system has a good merit as an experimental model system to produce the non-symbiotic (apo) and symbiotic (sym) host insect. In recent reported papers, the symbionts play important biological roles for the host insects. Meanwhile, juvenile hormone (JH) is one of major hormone synthesized corpora allata(CA) to control many physiology of insect. However, the study for cross-talk mechanism between symbionts and host hormones to control important physiological phenomenon of insects is almost none. In this study, we found that Riptortus speed up adult emerging and increase egg laying on presence of symbiont Burkholderia. Also we found that hexamerin proteins, which were controlled the expression by JH, were accumulated in sym-Riptortus hemolymph compare with apo-Riptortus. According as combined results, we hypothesized that the gut symbiont Burkholderia can control JH titer to conclude out beneficial effects such as development and reproduction of R. pedestris. To verify this hypothesis, we examined measurement of JH titer, expression of hexamerins as JH response genes and RNAi for hexamerin protein during whole Riptortus life on presence or absence of symbiont Burkholderia. All results demonstrated that gut symbiont controlled JH titer of Riptortus. Controlled JH amount by symbiont Burkholderia in host midgut regulated hexamerin protein expression for speeding up adult emerging and increasing egg production.

Citrus is one of the major fruits produced in Korea. There are about 20 species mainly grown in Jeju Island, Korea. Four representative species, which are quite different in the shape of leaf and the taste of fruit, were selected and were used to profile the transcriptomes. These species are ‘Miyagawa Wase’ (C. unshiu Marcov.) satsuma mandarin, ‘Kiyomi’ (C. unshiu Marcov. × C. sinensis) mandarin hybrid, ‘Dangyuja’ (C. grandis) and ‘Natsudaidai’ (C. natsudaidai). Classification of the up-regulated and down-regulated genes using the Cluster of Orthologous Groups of proteins (COG) database reveals that the number of genes included in each group differed significantly among the four species. Several genes that showed significant differences in expression on the microarray were selected and their expression patterns were examined by reverse transcription- ploymerase chain reaction. Metabolic genes such as tyrosine decarboxylase and β-glucosidase ligase were found to be highly expressed in Miyagawa Wase, relative to other species. On the other hand, the expression level of mannose phosphate isomerase was lower in Miyagawa Wase. An efflux pump gene was found to be up-regulated in Kiyomi, whereas cinnamyl-alcohol dehydrogenase was down-regulated. β-carotene 15,15’-dioxygenase, which is involved in the vitamin metabolism, was up-regulated in Natsudaidai. Interspecific differentiations of gene expression are analyzed in terms of the metabolic pathways and their possible roles in citrus species.