Research On The Composition Of Gut Microbial Communities Of Two Euchorthippus Species And Their Adaptability To Saline-Alkali Stress Plants

During the coevolution between insect gut microbiota and their hosts in the long-term scale,the community composition and diversity are often changed to adapt to altered food resources.Grasshoppers are important primary consumers in grassland ecosystem,and grassland plants are their main food resources.The grassland plants are subject to saline-alkali stress due to intensive climate change and other disturbed factors.The composition of gut microbial community and its adaptability to saline-alkali plants have not been clearly understood when grasshoppers feed these stressed plants with saline-alkali.In this study,the composition and diversity of gut microbial communities of two dominant grasshoppers(Euchorthippus cheui and E.unicolor)in Songnen grassland were studied,and their adaptability to saline-alkali plants was further analyzed.The main conclusions of this study are as follows:1.Composition of gut microbiota of E.cheui and E.unicolor were dominant by common taxa.Proteobacteria(Relative abundance: 71.080%,96.390%)and Tenericutes(Relative abundance: 28.050%,1.460%)at the phylum level,Alphaproteobacteria(Relative abundance:36.780%,11.830%)and Gammaproteobacteria(Relative abundance: 34.170%,84.530%)of the class level,Rickettsiales(Relative abundance: 36.570%,11.820%)and Enterobacteriales(Relative abundance: 33.430%,2.040%)of the order level,Anaplasmataceae(Relative abundance: 36.570%,11.820%)and Enterobacteriaceae(Relative abundance: 33.430%,82.040%)of the family level,and Wolbachia(Relative abundance: 36.570%,11.820%)and Enterobacter(Relative abundance: 19.280%,45.010%)of the genus level were abundant among gut microbial taxa.2.The gut microbial communities of E.cheui and E.unicolor showed interspecific differences.From the perspective of composition,the relative abundance of taxa such as Tenericutes of the phylum level or Wolbachia of the genus level in the gut of E.cheui was higher than that of E.unicolor,and the opposite was found for Proteobacteria of the phylum level or Pantoea of the genus level.Compared with gut microbes of E.cheui,E.unicolor had specific dominant taxa,such as Firmicutes of the phylum level or Lactococcus of the genus level.The Alpha diversity of the gut microbial community of E.cheui was significantly lower than that of E.unicolor,and the gut microbial community compositions of the two Euchorthippus species showed significant difference.3.Under the saline-alkali stress,the changes of gut microbial community lead to adaptability of E.unicolor to Leymus chinensis under the saline-alkali stress.Compared with the control,there was no significant change in the alpha diversity of gut microbiota of E.unicolor under saline-alkali treatment,but there was significant difference in the beta diversity.Meanwhile,the relative abundance of Pantoea,Enterobacter,Raoultella,Pseudomonas and Klebsiella of E.unicolor in the saline-alkali treatment increased significantly.The results of functional prediction showed that the increased abundance of Pantoea and Enterobacter enriched the functional genes of amino acid metabolism to adapt to the low amino acid content of L.chinensis.The increase of Raoultella and Pseudomonas abundance led to the enrichment of functional genes related to detoxification metabolism,which could cope with the high total phenol content of saline-alkali L.chinensis.The increase of Raoultella and Klebsiella abundance corresponds to the significant enrichment of functional genes such as carbohydrate metabolism,so as to adapt to the increase of cellulose and lignin content.In summary,the gut microbiota community of E.cheui and E.unicolor are dominant by same taxa groups,but there is difference in the two grasshopper species.E.unicolor can regulate the gut microorganisms to adapt to the saline-alkali stress on L.chinensis.This study enriches the understanding of gut microbial community of Orthoptera,further helps to uncover potential mechanisms on the survival of grasshopper in the saline-alkali grassland,and provides theoretical basis for further explanation of the biological functions of insect gut microorganisms.