Genome-wide identification, characterization and functional analysis of the chitianse and chitinase-like gene family in Diaphorina citri.

BACKGROUND: Insect chitinases play vital roles in postembryonic development, especially during the molting process, and are potential targets for the RNA interference (RNAi)-based insecticidal strategy. Systematic functional analyses of chitinase genes have already been conducted on numerous insect pests, but similar analyses have not been carried out on Diaphorina citri. RESULTS: Eleven chitinase/chitinase-like genes and one endo-ß-N-acetylglucosaminidase (ENGase) gene were identified in the Diaphorina citri genome using various bioinformatic tools. Transcriptomes of the integument and midgut from fifth-instar nymphs and freshly-emerged adults of Diaphorina citri were generated and sequenced. Potential functions of 12 chitinase/chitinase-like genes were examined during nymph-adult transitions. Four chitinase genes, including DcCht5, DcCht7, DcCht10-1 and DcCht10-2, were mainly expressed in the integument of fifth-instar nymphs. These four genes were also up-regulated significantly under 20-hydroxyecdysone (20E) treatments. RNAi-mediated knockdown of these four genes suggests that they are essential for nymph-adult transition. CONCLUSION: Our results demonstrated essential roles of the chitinase/chitinase-like genes during the nymph-adult transition in Diaphorina citri, which are potentially useful targets for controlling the Diaphorina citri pest. © 2022 Society of Chemical Industry.

Design, synthesis, fungicidal property and QSAR studies of novel ß-carbolines containing urea, benzoylthiourea and benzoylurea for the control of rice sheath blight.

BACKGROUND: Rice sheath blight is a globally important rice disease. Unfortunately, this critical disease has not been effectively controlled, and the intensive and continuous use of the same fungicide might increase the risk of resistance development in the pathogen. To discover new active agents against rice sheath blight, in this study, three series of ß-carboline urea, benzoylurea and benzoylthiourea derivatives were designed, synthesized and evaluated for in vitro and in vivo fungicidal activity against Rhizoctonia solani. RESULTS: All these compounds (EC50 : 0.131-1.227 mmol L-1 ) exhibited better fungicidal activity than harmine itself (EC50 : 2.453 mmol L-1 ). Significantly, compound 17c (EC50 : 0.131 mmol L-1 ) displayed the best efficacy in vitro and superior fungicidal activity compared with validamycin A (EC50 : 0.397 mmol L-1 ). Moreover, the in vivo bioassay also indicated that compound 17c could be effective for the control of rice sheath blight. CONCLUSION: Based on the bioassay result and quantitative structure-activity relationship (QSAR) information, structure modification in ß-carboline warrants further investigation and its benzoylurea derivative 17c, which showed the best fungicidal activities, could emerge as a potential fungicide against rice sheath blight. © 2018 Society of Chemical Industry.