Vitellin(Vn)homeostasis is central to the fecundity of oviparous insects.Most studies have focused on the synthesis and transportation of Vn as a building block for developing eggs during vitellogenesis;however,less i...Vitellin(Vn)homeostasis is central to the fecundity of oviparous insects.Most studies have focused on the synthesis and transportation of Vn as a building block for developing eggs during vitellogenesis;however,less is known about how the utilization of this nutrient reserve affects embryonic development.Here,we show that the single ortholog of the knirps and knirps-like nuclear receptors,KNRL,negatively regulates Vn breakdown by suppressing the expression of hydrolase genes in the brown planthopper,Nilaparvata lugens.KNRL was highly expressed in the ovary of adult females,and knockdown of KNRL by RNA interference resulted in the acceleration of Vn breakdown and the inhibition of embryonic development.Transcriptome sequencing analysis revealed that numerous hydrolase genes,including cathepsins and trypsins were up-regulated after KNRL knockdown.At least eight of the nine significantly enriched Gene Ontology terms for the up-regulated genes were in proteolysis-related categories.The expression levels of five selected trypsin genes and the enzymatic activities of trypsin in the embryos were significantly increased after KNRL knockdown.Moreover,trypsin injection prolonged egg duration,delayed embryonic development,accelerated Vn breakdown and severely reduced egg hatchability,a pattern similar to that observed in A7V/?L-silenced N.lugens.These observations suggest that KNRL controls Vn breakdown in embryos via the transcriptional inhibition of hydrolases.Generally,this study provides a foundation for understanding how embryo nutrient reserves are mobilized during embryogenesis and identifies several genes and pathways that may prove valuable targets for pest control.展开更多
基金The National Natural Science Foundation of China(31601634,31670414,31770474 and 31870361)the Distinguished Youth Talent Program of Fujian Agriculture and Forestry University(XJQ201722,XJQ19009)support this work.
文摘Vitellin(Vn)homeostasis is central to the fecundity of oviparous insects.Most studies have focused on the synthesis and transportation of Vn as a building block for developing eggs during vitellogenesis;however,less is known about how the utilization of this nutrient reserve affects embryonic development.Here,we show that the single ortholog of the knirps and knirps-like nuclear receptors,KNRL,negatively regulates Vn breakdown by suppressing the expression of hydrolase genes in the brown planthopper,Nilaparvata lugens.KNRL was highly expressed in the ovary of adult females,and knockdown of KNRL by RNA interference resulted in the acceleration of Vn breakdown and the inhibition of embryonic development.Transcriptome sequencing analysis revealed that numerous hydrolase genes,including cathepsins and trypsins were up-regulated after KNRL knockdown.At least eight of the nine significantly enriched Gene Ontology terms for the up-regulated genes were in proteolysis-related categories.The expression levels of five selected trypsin genes and the enzymatic activities of trypsin in the embryos were significantly increased after KNRL knockdown.Moreover,trypsin injection prolonged egg duration,delayed embryonic development,accelerated Vn breakdown and severely reduced egg hatchability,a pattern similar to that observed in A7V/?L-silenced N.lugens.These observations suggest that KNRL controls Vn breakdown in embryos via the transcriptional inhibition of hydrolases.Generally,this study provides a foundation for understanding how embryo nutrient reserves are mobilized during embryogenesis and identifies several genes and pathways that may prove valuable targets for pest control.
