| Up to now,the sericulture industry is still a traditional labor-intensive industry.The growth of mulberry leaves is limited by seasons and regions.Picking mulberry and raising silkworms is time-consuming,labor-intensive,and inefficient.Therefore,the development of time-saving labor-saving factory silkworm cultivation has become an important direction for the development of the silkworm industry.Establishing a standardized artificial feed sericulture system is an important or even necessary condition for achieving industrialized sericulture.The key foundations are the development of low-cost,nutritious artificial feeds,and the second is the selection of silkworm varieties with good adaptability to artificial feeds.Bombyx mori GS01 is a fine edible strain obtained from the silkworm gene resource bank of Southwest University.It can feed on leaves of various non-mulaceae plants such as cabbage.Exploring the genetic basis of GS01 for artificial feed infestation will not only help us understand the molecular mechanism of silkworm feeding,but also have important theories and practices for the research and development of low-cost artificial feed for silkworms and the selection and breeding of excellent silkworm varieties.significance.In this study,GS01,a silkworm omnivorous strain,was used as the research material to evaluate the practical potential of artificial feed rearing,and candidate genes involved in GS01 phagocytosis were identified by transcriptome sequencing.The main findings are as follows:1.Silkworm GS01 has good adaptability to artificial feedingInvestigated the feeding situation of two kinds of artificial feeds by the worm-feeding strain GS01 of silkworm,and found that GS01 not only has good feeding properties on ordinary granular artificial feeds,but also has good feeding properties and adaptability to low-cost artificial granular feeds with reduced mulberry leaf powder content Both types of artificial feeds can be cocooned and complete generation development.Compared with Guangshi No.1 and Youshi No.1 bred in Shandong,the weight,total cocoon weight,cocoon layer weight,cocoon weight production efficiency,and cocoon layer production efficiency of the three have decreased to a certain extent compared with mulberry leaf full-age breeding.From the significance of the comparison of the decline of mulberry leaves in various indicators,GS01 has good adaptability to ordinary pellet artificial feed,and has good practical potential for artificial feed raising.2.Transcriptome sequencing analysis of GS01 chemical receptorThe silkworm uses the chemosensory system(olfactory and taste)to recognize the volatile odors of plants in the environment for food selection.The chemical receptors of the silkworm are mainly antennae and jaw,as well as feet and epidermis.In this study,GS01,a wide-feeding strain and Dazao,a non-wide-feeding strain,were selected as the research materials.The antennae,jaw,and pectoral feet of the 5th-instar silkworm were used as materials.Total RNA was extracted and sequenced(Contains 3 biological replicates).Transcriptome sequencing analysis showed that there were 1583 genes with extremely significant differential expression in the antennae,1687 in the lower jaw,1882 in pectoral and foot,and 1034 differential genes in common in the three tissues.Our team’s early behavioral testing found that GS01 has weak olfactory sensitivity and cannot accurately target food sources and produce trending behavior.Further analysis found that there were two olfactory receptor genes in the extremely significantly differentially expressed genes analyzed by this transcriptome sequencing.3.Target BmOr39 and BmOr J as candidate genes involved in GS01 diet formationThe olfactory receptor(Or)gene is the key to the formation of olfactory in silkworm.Based on the new silkworm genome,a total of 73 olfactory receptor genes were re-identified in this study,and they were serially numbered and named.Through detailed analysis and comparison,they were anchored to the specific positions of 28 silkworm chromosomes..Among the extremely significantly differentially expressed genes analyzed by this transcriptome sequencing,there are two olfactory receptor genes,namely BmOr39 and BmOr J,which are respectively located in the two previously located Nos.3 and 21 that are associated with the GS01 eutrophic mutation On the chromosome,we use these two olfactory receptor genes as candidate genes for GS01 olfactory mutation.4.The expression patterns of BmOr39 and BmOr J are consistent with the feeding rules of silkworm.BmOr39 and BmOr J genes tissue and period expression profile results show that the two genes have low expression in almost all tissues.It is speculated that the two genes not only function as olfactory receptor genes but also participate in other life activities of the silkworm;The expression of these genes was down-regulated during the dormant silkworm and up-regulated during the emergence of the silkworm.It is speculated that this trend may be related to the behavior of the silkworm not eating during sleep and feeding during sleep.Investigated the correlation between BmOr39 and BmOr J gene expression and GS01 phagophagous phenotype,and detected the antennae of BmOr39 and BmOr J genes in wild-type Dazao and phagotrophic strain GS01 from the fourth instar,fourth instar dormant and fifth instar larvae by q RT-PCR.The results showed that compared with wild type Dazao,the expression of BmOr39 and BmOr J genes in GS01 was down-regulated,and the expression of silkworm antennae was more down-regulated.Therefore,it is speculated that the expression of BmOr39 and BmOr J genes is related to the feeding behavior of silkworm larvae.5.Genomic Variation Analysis of BmOr39 and BmOr J in Silkworm GS01The ORF sequences of candidate genes BmOr39 and BmOr J were investigated in multiple wild-type strains and the silkworm phagocytosis line GS01.It was found that in the phagomorphic strain GS01,there were 5 SNPs and 1 specific 2bp base on the ORF of BmOr39.Base deletion,leading to the premature termination of the protein sequence of the gene,but the functional domain of the gene was not disrupted;it was found through multi-line verification that compared to multiple wild-type lines,the ORF of BmOr J was present in the edible line GS01 Nine SNPs and one specific single base deletion resulted in premature translation termination of the protein and disrupted the functional domain of the gene.This further indicates that BmOr39 and BmOr J genes are involved in the formation of feeding mutations in silkworm GS01,and their functions need to be further verified.In summary,we used the silkworm phagocytosis strain GS01 as the research material,and identified the excellent adaptability of the GS01 strain to artificial feeding of all ages.We also integrated molecular mapping,transcriptome sequencing,re-identification of olfactory receptor genes,and candidate genes.As a result of specific mutation analysis,two genes BmOr39 and BmOr J involved in the feeding of silkworms were identified.In the worm-feeding strain GS01,the ORF sequences of the BmOr39 and BmOr J genes were mutated,protein translation was terminated prematurely,and gene expression was significantly down-regulated,suggesting that the two genes may be formed by the GS01 phagocytosis Important genetic factors.This research not only helps us to further understand the molecular basis of the formation of the silkworm’s feeding habits,but also has important theories and practices for the development and improvement of low-cost artificial feed for silkworms,the breeding of polyphagous silkworm varieties,and the selection of excellent adaptive strains.significance. |
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