Abstract:

【Objective】In order to provide important basis for effective pests control based on RNAi, the temporal and spatial expression characterizations and the biological functions of chitinase family genes from L. migratoria manilensis were investigated and chitinase genes causing locusts death during development were screened.【Method】Chitinase-like gene fragments were obtained from locustDB and the sequences of these genes were analyzed by bioinformatics methods. The first-strand cDNAs were synthesized using RNA isolated from the fourth day of different locust stages and the various tissues of the 5th nymphs and RT-PCR was carried out to analyze the gene expression patterns. Biological functions of LmCht6 that was highly expressed in the integument were studied by RNA interference. 【Result】 Seven chitinase-like gene fragments were gained from locustDB. The RT-PCR results showed that the temporal and spatial expression patterns among seven chitinase genes were significantly different and LmCht6 was highly expressed in the integument. RNA interference of LmCht6 showed that the corresponding transcript level was reduced in the nymphs after being injected with LmCht6 dsRNA compared with the control insects. The nymphs injected with LmCht6 dsRNA displayed slow development and failed to detach old cuticle during molting. Consequently, 72.2% of mortalities were observed.【Conclusion】More than one chitinase gene was present in locust and the temporal and spatial expression profiles of these genes were different. The RNAi results indicated that LmCht6 play an important role in the molting process of L. migratoria manilensis, and gene silencing can result in its ecdysis block and even death.

Key words: Locusta migratoria manilensis, chitinase gene, RT-PCR, RNA interference