| Microbes are ubiquitous in nature and contribute various functions that affect the survival and metabolism of hosts. The insects also contain microbiota, such as bacteria, fungi and virus. Up to data, many scientists focused on microbiotal communities that are related to insects and identified kinds of important roles of microbiota in insects. Cultivation of fungi in the lab is the most traditional method, and culture-independent methods, such as DGGE and T-RLFP, subsequently, the next-generation sequencing is used in study of fungal diversity. All these methods gradually provided more and more fungal sequences and taxa. Although this advanced method has been used by scientists to discover multiple important findings regarding the relationships between microbes and their hosts, due to the targeted sequencing for large amounts of fungal barcoding data and the price is inexpensive.In parallel with the technological advancement of high-throughput sequencing, there are many insects have obtained its genome and meta-transcriptome data, the total number of raw genomic or transcriptome sequences used to analyzing the host information and discovered a large amount of valuable information, but the non-host sequences which excluding the host assembled genome sequences has been overlooked. Uncover of the abundant fungal information that hidden in the non-host sequences, is significance in study of fungal microbiota.In this study, we analyze the richness and composition of fungal community in the fig wasp Ceratosolen solmsi bynon-host sequences. The non-host sequences included the genome and transcriptome sequences, the non-host sequences of transcriptome contained larval female and male, pupal female and male, pupal female and male, adult female and male; the non-host sequences of genome contained adult male.After excluding the assembled genome of C. solmsi, the percentage of non-host sequences ranged from 17% to 34%.To study of richness and composition of fungal community in non-host genome sequences, firstly, comparing two fungal reference datasets, internal transcribed spacer (ITS) and large ribosomal subunit (LSU) of rRNA, the ITS dataset discovered a more diverse fungal community and was therefore selected as the reference dataset for evaluating the fungal community based on the non-host sequences. Secondly, the threshold of 95% sequence identity revealed many more matched fungal sequences and fungal richness in the non-host sequences than those by identities above 95%. Thirdly, based on the threshold of 95% sequence identity, the fungal community of NHRG-CS was primarily composed of Saccharomycetes (88.4%) and two other classes (Agaricomycetes and Sordariomycetes,8.3% in total). Compared with the fungal community of other reported fig wasps, Agaricomycetes and Eurotiomycetes were found to be unique to C. solmsi. In addition, the ratio of total fungal sequences to NHRG-CS was estimated to be at least 4.8×10-3, which indicated that a large amount of fungal data was contained in NHRG-CS. However, rarefaction measure indicated that a deeper sequencing coverage with NHRG-CS was required to discover the entire fungal community of C. solmsi. This study investigated the richness and composition of fungal community in NHRG-CS and provided new insights into the efficient study of microbial diversity using non-host sequencing data.To discovered fungal diversity in non-host transcriptome sequences, we used ITS reference database to investigate the fungal diversity, and the dynamics of fungal diversity in different developmental stages of host fig wasp Ceratosolen solmsi was first represent. We followed such process:Bowtie 1, Bowtie 2 and Pathoscope 2, step by step, the accurate and comprehensive fungi have been obtained. Firstly, by comparing three fungal reference databsets of adult male--ITS, genome and mRNA, we found the ITS result discovered the greatest fungi than others, so selected ITS reference database as optimal database; while compared the ITS result of non-host genomic sequences with non-host transcriptome sequences, which showed two-third of fungal genera by transcriptome sequences were included in non-host genomic result. Secondly, by analysing the fungal rarefaction curves at 97% identity by ITS results of all samples, we found nearly saturate fungal diversity was discovered except larval stage. Thirdly, we used the total number of fungal reads from the host genome in criterion to estimate the percentage of fungal sequences and the abundant of fungi, the percentage of fungal sequences ranged from 0.02% to 0.89% andall stages of host harbored diverse of fungi. For the shared fungal genera in those developmental stages which the Galactomyces is the most abundant. The dynamic changes of fungal communities are consistent with developmental stages by up-95% and lower-95% of rarefaction curves. Therefore, the ITS database and 97% identity for fungal screening in host meta-transcriptome data is suitable. |
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