Anastomosis Groups and Mycovirome of Rhizoctonia Isolates Causing Sugar Beet Root and Crown Rot and Their Sensitivity to Flutolanil, Thifluzamide, and Pencycuron

Abstract

Anastomosis groups (AGs) or subgroups of 244 Rhizoctonia isolates recovered from sugar beet roots with symptoms of root and crown rot were characterized to be AG-A, AG-K, AG-2-2IIIB, AG-2-2IV, AG-3 PT, AG-4HGI, AG-4HGII, and AG-4HGIII, with AG-4HGI (108 isolates, 44.26%) and AG-2-2IIIB (107 isolates, 43.85%) being predominate. Four unclassified mycoviruses and one hundred and one putative mycoviruses belonging to six families, namely Mitoviridae (60.00%), Narnaviridae (18.10%), Partitiviridae (7.62%), Benyviridae (4.76%), Hypoviridae (3.81%), and Botourmiaviridae (1.90%), were found to be present in these 244 Rhizoctonia isolates, most of which (88.57%) contained positive single-stranded RNA genome. The 244 Rhizoctonia isolates were all sensitive to flutolanil and thifluzamide, with average median effective concentration (EC50) value of 0.3199 ± 0.0149 μg·mL−1 and 0.1081 ± 0.0044 μg·mL−1, respectively. Among the 244 isolates, except for 20 Rhizoctonia isolates (seven isolates of AG-A and AG-K, one isolate of AG-4HGI, and 12 isolates of AG-4HGII), 117 isolates of AG-2-2IIIB, AG-2-2IV, AG-3 PT, and AG-4HGIII, 107 isolates of AG-4HGI, and six isolates of AG-4HGII were sensitive to pencycuron, with average EC50 value of 0.0339 ± 0.0012 μg·mL−1. Correlation index (ρ) of cross-resistance level between flutolanil and thifluzamide, flutolanil and pencycuron, and thifluzamide and pencycuron was 0.398, 0.315, and 0.125, respectively. This is the first detailed study on AG identification, mycovirome analysis, and sensitivity to flutolanil, thifluzamide, and pencycuron of Rhizoctonia isolates associated with sugar beet root and crown rot.

A Novel Strain of Fusarium oxysporum Alternavirus 1 Isolated from Fusarium oxysporum f. sp. melonis Strain T-BJ17 Confers Hypovirulence and Increases the Sensitivity of Its Host Fungus to Difenoconazole and Pydiflumetofen

“…The complementary DNA (cDNA) of a single strain was synthesized using Reverse Transcriptase M-MLV (TaKaRa, Dalian, China) following the manufacturer’s protocol. The RT-PCR was performed with a 25 µL PCR mixture as Zhao et al described [ 37 ]. The PCR products were verified by 1% agarose gel electrophoresis and sequenced by the Tsingke Biotechnology Co., Ltd. (Beijing, China).…”

“…Sensitivity of the two strains, T-BJ17 and T-BJ17-VF, to difenoconazole and pydiflumetofen were evaluated in vitro as described in previous studies [ 37 , 43 ], with minor modifications. The final concentrations of difenoconazole and pydiflumetofen were 5.00, 1.00, 0.50, 0.10, and 0.05 µg/mL, and 1, 0.50, 0.10, 0.05, and 0.01 µg/mL, respectively.…”

“…The final concentrations of difenoconazole and pydiflumetofen were 5.00, 1.00, 0.50, 0.10, and 0.05 µg/mL, and 1, 0.50, 0.10, 0.05, and 0.01 µg/mL, respectively. The median effective concentration (EC 50 ) of difenoconazole and pydiflumetofen against the two strains was calculated using previously described methods [ 37 , 43 ]. Three replicates were used for each strain–fungicide combination, and the experiment was repeated three times.…”

A Novel Strain of Fusarium oxysporum Virus 1 Isolated from Fusarium oxysporum f. sp. niveum Strain X-GS16 Influences Phenotypes of F. oxysporum Strain HB-TS-YT-1hyg

“…The sensitivity of the two strains, HB-TS-YT-1 hyg and HB-TS-YT-1 hyg -V, to difenoconazole [Active ingredient (AI): 94.50%], prochloraz (AI: 98.00%), and pydiflumetofen (AI: 98.00%) was evaluated in vitro, as described in a previous study [41]. The PDA media were amended with difenoconazole, prochloraz, and pydiflumetofen to establish the final concentrations of 5.00, 1.00, 0.50, 0.10, and 0.05 µg/mL, 0.50, 0.10, 0.05, 0.01, and 0.005 µg/mL, and 1.00, 0.50, 0.10, 0.05, and 0.01 µg/mL, respectively.…”

“…The PDA media were amended with difenoconazole, prochloraz, and pydiflumetofen to establish the final concentrations of 5.00, 1.00, 0.50, 0.10, and 0.05 µg/mL, 0.50, 0.10, 0.05, 0.01, and 0.005 µg/mL, and 1.00, 0.50, 0.10, 0.05, and 0.01 µg/mL, respectively. The median effective concentration (EC 50 ) of difenoconazole, prochloraz, and pydiflumetofen against the two strains was calculated as described by Zhao et al [41]. Four replicates were used for each strain-fungicide combination, and the experiment was repeated three times.…”