Abstract: 【Aim】 Receptor for activated C kinase 1 (RACK1) is involved in the transduction of some crucial signals in multicellular organisms to regulate their growth and development. The aim of the present study is to clone the RACK1 gene PxyRACK1 in the diamondback moth, Plutella xylostella, to vestigate its expression pattern and to find out its effect on pupation as well as its underlying mechanism. 【Methods】 The full-length cDNA of PxyRACK1 was cloned and subjected to bioinformatic analysis, and its expression profiles at different developmental stages (egg, 1st-4th instar larvae, prepupa, pupa and adult) of P. xylostella were detected by qPCR. The RNA interference of PxyRACK1 was carried out by microinjecting PxyRACK1 dsRNA into the 4th instar larvae of P. xylostella. After RNAi, the expression levels of PxyRACK1 and pupal specifier PxyBr-Z2/3 were detected, and the mortality, pupation rate, average pupation time and pupal weight of P. xylostella were recorded and calculated. 【Results】 The full-length cDNA of PxyRACK1 (GenBank accession no.: MW160739) of P. xylostella is 1 148 bp in length, with an open reading frame of 960 bp encoding 319 amino acids. The predicted amino acid sequence of PxyRACK1 protein contains seven WD40 repeats, each WD40 repeat consisting of 39-42 amino acids. PxyRACK1 was ubiquitously expressed at various developmental stages of P. xylostella, with the highest expression level in the day-2 4th instar larva and the lowest expression level in the 2 dold pupa. At 24 h after microinjection of dsPxyRACK1, the expression levels of PxyRACK1 and PxyBr-Z2/3 in the 4th instar larvae in the treatment group were significantly decreased by 36.26% and 83.46%, respectively, as compared to those in the control group (dsGFP injection group), and the microinjection of dsPxyRACK1 resulted in the increase in mortality, delay in pupation and decrease in pupation rate and pupal weight. 【Conclusion】 The results suggest that PxyRACK1 is involved in the regulation of pupal metamorphosis of P. xylostella. This study provides clues for further exploring of the signal regulation pathway of metamorphosis and developing novel insect growth regulators.

Key words: Plutella xylostella, PxyRACK1; PxyBr-Z2/3, RNA interference, microinjection