The Invasion Mechanism Study Of Apple Snail(Pomacea Canaliculata) Based On Mulit-omics

As one of the members of the national list of invasive alien invasive species,the apple snail Pomacea canaliculata is widely distributed in various provinces in the south of China,and has formed geographical populations with different climate adaptability.Because of its fast growth rate,strong ability to resist environmental pressure,large amount of spawning and adapt to the ecological width,the apple snail has been widely invaded all over the world and caused great economic loss.However,the mechanism of its invasion has not been revealed.Using the three generation of Pacbio sequencing,its genome with the size of 440 Mb was successfully assembled and the genome was promoted to chromosomes level by Hi-C technology.Combining the analysis of gene family,repeat sequence,transcriptiome and intestinal metagenomics,the molecular mechanism of snail invasion was explained from 4 previously proposed hypothesis,namely the inherent superiority hypothesis,the competitiveness enhancement hypothesis,the new weapon hypothesis and the mutual benefit hypothesis.In terms of the inherent superiority hypothesis,the WGCNA(weighted gene co-expression network analysis)analysis of 33 transcriptomes shows that the core regulatory element is an energy compensation strategy,when the apple snail responds to environmental pressure and immune stimuli.Orexin,enterotryptin,dopamine,and thyrotropin releasing hormone receptors are at the core of the regulatory position,which means that the snails can use neurohormone regulation to stimulate appetite and enhance energy conversion when they are subjected to environmental or immune pressure to compensate for the loss of energy against stress.In addition,the apple snail has stronger cellular homeostasis and immune system.On the hypothesis of competitiveness enhancement,the genome of apple snail has rapid evolution and plasticity.Especially one group of the DNA transposons,have recently expanded peak,and their related gene expression activity has been enhanced.The CYP450 family expanded and evolved rapidly in the 2U subfamily.In addition,the CYP450 family genes exhibit versatile phenotypic plasticity in response to environmental stimuli and immune stimulation.In terms of the new weapon hypothesis,the snail can utilize the unique perivitelline fluid protein(PVF)in eggs to provide protective neurotoxins and red warning colors.In terms of mutual benefit hypothesis,the intestinal microbes of the snail can assist in the detoxification of the benzene ring substances and the digestion of cellulose,in order to enhance the environmental adaptability and to expand the source of energy.The results of this study will promote and deepen the understanding of the invasion mechanism of snail and provide reference for other invasive species.It will also provide a theoretical basis for the development of the prevention and control methods of the apple snail,in order to ensure the ecological security,agricultural production and human health in China.