Abstract
Hexokinase (HK) is a key enzyme in chitin biosynthesis in insects and plays an important role in development and energy regulation. It also performs a crucial role in the synthesis of Glucose-6-phosphate and its putative functions are studied via injection of dsRNA corresponding to the hexokinase gene from Cnaphalocrocis medinalis (CmHK). This study was designed to analyze the characteristics and expression patterns of HK-related genes in various tissues of C. medinalis at different developmental stages. The CmHK ORF is a 1359 bp in length, encoding a protein of 452 amino acids, with homology and cluster analysis showing that CmHK shares an 85.11% sequence similarity with hexokinase from Ostrinia furnacalis. CmHK was highly expressed in the ovary and in the fifth instar larvae. Injection of dsCmHK significantly suppressed mRNA expression (73.6%) 120 h post-dsRNA injection as compared to a control group. The results demonstrated an increased incidence of larval and pupal mortality of 80% and 78%, respectively, with significant variation in the sex ratio between males (68.33%) and females (35%), overt larval deformities, and a reduction in average weight gain observed 120 h post-dsRNA injection. In addition, dsCmHK-injected C. medinalis showed a significant reduction in ovulation per female and larval hatching rate, along with increased larval and pupal mortality and variation in male and female emergence over three generations (G1, G2, and G3). Taken together, the outcomes of the study provide a foundation to study gene function and a new dimension to control C. medinalis by transgenic RNAi technology.
Highlights
The cuticle is an integral part of the exoskeleton that plays a vital role in the growth and development of an organism
Upon the NCBI Blast, CmHK showed the highest similarity with OfHK of O. furnacalis (XM_028310711, 88.37% identity), followed by MsHK
Our results showed that phenotypic expressions, larval weight, transformation of larvae–pupae–adult emergence, oviposition, and mRNA level were disrupted after knockdown of CmHK (Figures 5 and 6)
Summary
The cuticle is an integral part of the exoskeleton that plays a vital role in the growth and development of an organism In insects, it plays a pivotal role in protecting them against adverse environments, pathogens, parasites, hazardous chemicals, and provides structural support and movement [1]. It plays a pivotal role in protecting them against adverse environments, pathogens, parasites, hazardous chemicals, and provides structural support and movement [1] Insects periodically shed their old cuticle or cuticular parts and replace them with new ones, especially during molting from one stage to another in which chitin plays a crucial role [1]. Chitin is the second most important and widespread amino polysaccharide in nature after cellulose. Disruption of natural processes of chitin synthesis and degradation can cause abnormalities, leading to death in severe cases [7]
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