Analysis of Biocontrol Effects of Mycoviruses on Sesame Stem Rot

WANG Jing; NI Yunxia; HE Bipo; ZHANG Chunyan; ZHAO Hui; LIU Xintao; ZHAO Xinbei; LIU Hongyan

doi:10.15933/j.cnki.1004-3268.2025.10.011

Abstract：Sesame stem rot is caused by the fungal pathogen Macrophomina phaseolina,and is the significant disease of sesame.Previous studies have found that M.phaseolina carries abundant resources of mycoviruses,while while the hypovirulent mycovirus is the green solution to control crop disease.In order to obtain the biocontrol strains against sesame stem rot,the biological characteristics of three hypovirulent strains(2012-19,2012-22,2012-161)carrying mycoviruses were studied,and the strong virulent strain 2012-63 was used as the control.The pathogenicity was compared by in vitro leaf and in vivo stem inoculation,and the control effect of three hypovirulent strains on sesame stem rot was evaluated by soil inoculation method.The results showed that the colony morphology of the highly virulent strain 2012-63 on the PDA plate showed radial growth,the aerial mycelium was lush,and the growth rate was 20.44 mm/d;the colony morphology of hypovirulent strains 2012-19,2012-22 and 2012-161 showed irregular growth,with obvious fanning area,and the growth rate was 2.94-13.19 mm/d,and the average growth rate of the three hypovirulent strains was significantly 60.54％lower than that of the highly virulent strain.After five days of inoculation of detached leaves,the lesions of the highly virulent strains had expanded to the entire leaf surface,resulting in browning and decay of the leaf surface,while the three hypovirulent strains only formed 28.26 mm2 lesions at the inoculation site.After 8 days of stem inoculation,the relative area under the disease progression curve(RAUDPC)of the three hypovirulent strains was 2.10-5.90,and the average RAUDPC of the three hypovirulent strains was reduced by 92.27％significantly than high-virulent strains(45.55).The indoor pot experiment showed that the control effects of three hypovirulent strains on sesame stem rot were 44.90％,56.40％and 75.30％,respectively,while the control effects of biocontrol agent(Trichoderma harzianum)and chemical agent(50％carbendazim)were 53.65％and 87.10％,respectively.It can be seen that the hypovirulent strain of M.phaseolina carrying the related virus can be used as a biological control resource to control sesame stem rot.