Effects of the Mycovirus BbOCuV1 on the Growth and Development of Host Beauveria bassiana and Its Pathogenicity to Ostrinia furnacalis Larvae

doi:10.13560/j.cnki.biotech.bull.1985.2025-0053

Abstract

Abstract:

Objective By clarifying the effects of the mycovirus Beauveria bassiana orthocurvula virus 1(BbOCuV1) on the growth and development of the host Beauveria bassiana and on the pathogenicity of insect pests, we proved whether the mycovirus is a key factor that cause the decline of the pathogenicity of B. bassiana. Method Detoxification and horizontal transmission were used to study the effects of BbOCuV1 on the growth rate, spore production and biomass of B. bassiana colonies. The pathogenicity of B. bassiana on the second instar larvae of the Ostrinia furnacalis was determined. Transcriptome analysis was used to define the molecular mechanism of fungal viruses affecting the host strains. Result The growth rate, spore production and biomass of host strain significantly increased after virus BbOCuV1 infection, while the pathogenicity towards the insect pest significantly decreased. Transcriptome analysis showed that growth and development-related pathways and genes expression significantly upretulated, after virus infection, while the expressions of genes related to insect epidermis penetration and toxin metabolism significantly downregulated. Conclusion The growth and development as well as biomass of B. bassiana infected with virus BbOCuV1 increase, but pathogenicity against pests reduces, indicating that mycovirus infection is an important factor in the pathogenicity decline of B. bassiana to pests.

Key words: Beauveria bassiana, mycovirus, BbOCuV1, biological character, biological control

JIA Xue, SUI Li, ZOU Xiao-wei, LU Yang, ZHANG Zheng-kun, LI Qi-yun. Effects of the Mycovirus BbOCuV1 on the Growth and Development of Host Beauveria bassiana and Its Pathogenicity to Ostrinia furnacalis Larvae[J]. Biotechnology Bulletin, 2025, 41(7): 312-325.

Figures/Tables 11

Table 1 Primers for sequence amplification

引物名称 Primer name	序列 Sequence （5′-3′）	片段大小 Fragment size （bp）
dsRNA1-F1	CCTTCCTCCGGTCACTGAACC	1 419
dsRNA1-F2	GGTGGTGCTAAAGCTAAGGTGTCG	1 419
dsRNA1-R1	CGCGCTCAGTCTTGCCAT	1 085
dsRNA1-R2	GTCAACAGACCTACAACCGACACC	1 085
dsRNA2-F1	GCGCAGGTGGGAGGACA	1 019
dsRNA2-F2	ATCCAGCCATCATCGCGC	1 019
dsRNA2-R1	CCTGACCGAACAAATGCTCACC	935
dsRNA2-R2	CCATCGGTGCGGACGG	935

Fig. 1 dsRNA extraction and RT-PCR detection of Beauveria bassiana strain BbOCuV1A: Each lane indicates the test result of dsRNA extraction in strain BbOCuV1; "+" is dsRNA treated with DNase I and S1 nuclease; "-" is the dsRNA without enzymatic treatment. B: Each lane indicates the RT-PCR detection for strain BbOCuV1; "+" is a positive control for RT-PCR; and "-" is a negative control for RT-PCR and BbOCuV1-F

Fig. 2 dsRNA extraction and RT-PCR detection of B. bassiana strain BbOFDHOCuV and BbOFDH1-5-GFPA: dsRNA extraction test result in strain BbOFDHOCuV; "+"is dsRNA treated with DNase I and S1 nuclease; "-" is the dsRNA without enzymatic treatment. B: RT-PCR detection for strain BbOFDHOCuV; "+" is a positive control for RT-PCR, and "-" is a negative control for RT-PCR

Fig. 3 Colony morphologies and growth rates of B. bassiana inoculated on PDA mediumA: Colony morphology of strain BbOFDHOCuV and BbOFDH; B: colony morphology of strain BbOCuV1and BbOCuV1-F strains; C: growth rates of BbOFDHOCuV and BbOFDH strains; D: growth rates of BbOCuV1 and BbOCuV1-F strains. ** indicates P＜0.01; *** indicates P＜0.001, the same below

Fig. 4 Morphology of mycelium tip of B. bassiana

Fig. 5 Strain's sporulation yield per unit areaA: Sporulation yield per unit area of the toxified strain. B: Sporulation yield per unit area of the detoxified strain

Fig. 6 Determination of the biomass of B. bassiana strainsA: Biomass measurement of the toxified strains. B: Biomass measurement of detoxified strains

Fig. 7 Survival rates of 2-instar O. furnacalis within 8 dA: Survival rate of 2-instar Ostrinia furnacalis larvae infected with toxified strains B: Survival rate of 2-instar O. furnacalis larvae infected with detoxified strains;*P<0.05

Fig. 8 Transcriptome profile of RNA-Seq dataA: Principal component analysis of virus-free and BbOCuV1 groups; B: Volcano plot of RNA-Seq data using log2 fold change and log10p-value. Red and green dots denote up- and down-regulated genes, respectively, and blue dots indicate genes with no significant expression

Fig. 9 GO and KEGG enrichment analyses of DEGsA: GO enrichment analysis of upregulated genes. B: GO enrichment analysis of downregulated genes. C: KEGG enrichment analysis of upregulated genes. D: KEGG enrichment analysis of downregulated genes

Table 2 Padj values of differential genes

Gene ID	Padj
BBA_00890	5.05031204527094e-37
BBA_01635	5.19645125134483e-05
BBA_02155	7.19194419245941e-06
BBA_01808	4.57389790420523e-12
BBA_02822	1.45371968945862e-07
BBA_04028	0.00497034986646022
BBA_08424	2.58045865685601e-06
BBA_08699	0.00121775638944784
BBA_03616	0.00170577409824362
BBA_04374	8.74503508574553e-20
BBA_07338	1.08247806189268e-12
BBA_09043	5.05031204527094e-37
BBA_00611	4.4575588085647e-05
BBA_00635	0.000102945242727946
BBA_00702	1.47055069946437e-23
BBA_02264	0.00174335718176381
BBA_09043	5.05031204527094e-37

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