Study On The Function Of Tyrosine Metabolic Pathway In The "Tree Top Disease" Of Lymantria Dispar

The subject about the tree top disease caused by Lymantria dispar multiple nuclear polyhedrovirus(Ld MNPV)has been the focus of many experts and scholars,but the mechanism is still unclear.In this study,L.dispar larvae were infected by Ld MNPV,fungi,and bacteria,separately.And the behavior of infected larvae and transcriptome analysis were carried out to study the differences between viruses and other pathogens.By analyzing the difference in transcriptome data between infected and healthy gypsy moth,the tyrosine metabolism pathway related to energy metabolism and which is also the upstream of the tricarboxylic acid cycle may be related to tree top disease.The genes in the tyrosine metabolism pathway and can influence the tricarboxylic acid circulation pathway,hpd and gstz1 were used as target to knock down by RNAi to discuss the role of this pathway to tree top disease.The results are as follows:1.Observe the climbing height within 72 hours of gypsy moth larvae treated with three pathogens: virus,fungus,and bacteria,and we can find that the larvae infected by the virus climb up obviously,which is significantly different from the larvae infected by bacteria or fungus(P<0.05).In addition,there is no significant difference between the fungus group and the bacteria group.2.Transcriptome sequencing was employed screen identified the differentially expressed genes in the gypsy moth infected with viruses,bacteria,and fungi at 72 hours,and identified 44994 unigenes.Compared with larvae infected by Ld MNPV,larvae infected by Staphylococcus aureus showed 308 up-regulated genes and 263 downregulated genes.Compared with larvae infected by Ld MNPV,larvae infected by Metarhizium anisopliae showed 623 up-regulated genes and 413 down-regulated genes.Compared with larvae infected by Staphylococcus aureus,larvae infected by Metarhizium anisopliae showed 417 up-regulated genes and 177 down-regulated genes.3.In pairwise comparison,KEGG enrichment analysis showed that Toll and IMD signal pathways were the most enriched pathways.In addition,peroxisome pathway,pentose and glucuronate interconversions pathway,metabolism of xenobiotics by cytochrome P450 pathway,lysosome pathway,and pyruvate metabolism pathway were other enriched pathways.4.Compared with larvae infected by bacteria or fungus,the larvae infected by virus showed the pathways related to energy metabolism such as the nicotinate and nicotinamide metabolism,pyruvate metabolism,citrate cycle,oxidative phosphorylation,cholesterol metabolism,which contains many up-regulated genes.It showed the climbing of gypsy moth induced by Ld MNPV was related to energy metabolism;and there were many up-regulated genes in the neuroactive ligand-receptor interaction pathway,which also showed the climbing of gypsy moth induced by Ld MNPV was related to nervous system.5.The hpd and gstz1 genes in the tyrosine metabolism pathway related to energy metabolism of the gypsy moth were selected to verify whether the climbing of gypsy moth infected by virus was related to energy metabolism.Feeding ds RNA that interfered with hpd and gstz1 genes did not cause death of Lymantria dispar larvae,and it also did not advance or delay the time when Lymantria dispar multiple nuclear polyhedrosis virus killed Lymantria dispar larvae.Compared to larvae fed with Lymantria dispar multiple nuclear polyhedrosis virus,the larvae fed with ds RNA that interfered with the hpd gene had a significantly weaker upward climbing ability.6.Compared to the larvae fed with Lymantria dispar multiple nuclear polyhedrosis virus,the larvae fed with ds RNA that interfered with the gstz1 gene had an extremely significantly weaker upward climbing ability.The above results indicated that gypsy moth larvae showed upward climbing behavior after infected by the virus,which was obviously different from the behavior after infected by fungus or bacterium,and it was a special biological phenomenon caused by virus.Transcriptomics data analysis showed that the gene expression related to energy metabolism and nervous system pathways of gypsy moth larvae infected by virus were significantly higher than larvae infected by bacteria or fugus.Further research found that the hpd and gstz1 genes in the tyrosine metabolism pathway related to energy metabolism of the gypsy moth had a certain correlation with the upward climbing behavior.