Surveillance of Pathogenicity of Rhizoctonia solani Japanese Isolates with Varied Anastomosis Groups and Subgroups on Arabidopsis thaliana.

Mai Mohsen Ahmed Abdelghany,Maria Kurikawa,Yoshiteru Noutoshi,Yusuke Kouzai,Mikihiro Yamamoto,Megumi Watanabe,Kazuhiro Toyoda,Hidenori Matsui,Yuki Ichinose

doi:10.3390/life12010076

Mai Mohsen Ahmed Abdelghany, Maria Kurikawa + Show 7 more

Open Access

https://doi.org/10.3390/life12010076

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Abstract

Rhizoctonia solani is a necrotrophic plant pathogen with a wide host range. R. solani is a species complex consisting of thirteen anastomosis groups (AGs) defined by compatibility of hyphal fusion reaction and subgroups based on cultural morphology. The relationship between such classifications and host specificity remains elusive. Here, we investigated the pathogenicity of seventeen R. solani isolates (AG-1 to 7) in Japan towards Arabidopsis thaliana using leaf and soil inoculations. The tested AGs, except AG-3 and AG-6, induced symptoms in both methods with variations in pathogenicity. The virulence levels differed even within the same AG and subgroup. Some isolates showed tissue-specific infection behavior. Thus, the AGs and their subgroups are suggested to be not enough to define the virulence (host and tissue specificity) of R. solani. We also evaluated the virulence of the isolates on Arabidopsis plants pretreated with salicylic acid, jasmonic acid, and ethylene. No obvious effects were detected on the symptom formation by the virulence isolates, but ethylene and salicylic acid slightly enhanced the susceptibility to the weak and nonvirulent isolates. R. solani seems to be able to overcome the induced defense by these phytohormones in the infection to Arabidopsis.

Highlights

Surveillance of Pathogenicity of Rhizoctonia solani Japanese Isolates with Varied Anastomosis Groups and Subgroups on Arabidopsis thaliana
We previously found that foliar application of salicylic acid (SA) to B. distachyon and rice could induce sheath blight resistance caused by R. solani anastomosis groups (AGs)-1 IA [24]
National Agricultural and Food Research Organization (NARO) Genebank: four AG-1 isolates, eight AG-2 isolates, and single isolates for each of AG-3, AG-4, AG-5, AG-6, and AG-7 that were isolated from diseased crops and soil (Table 1)

Summary

Fungal Isolates and Plant Materials

Seventeen Rhizoctonia solani isolates were obtained from the Genebank of the National. MAFF numbers are descriptors for the microorganism genetic resources assigned by NARO (National Agriculture and Food Research Organization) Genebank in Japan. DifcoTM potato dextrose broth and 2% agar). The seeds were stored for three days at 4 ◦ C in dark condition before sowing. Arabidopsis seeds were plated on half-strength Murashige and Skoog (1/2MS) medium plates (2.23 g/L MS salt (Nihon Pharmaceutical, Tokyo, Japan) enriched with 0.1% (v/v). Gamborg’s vitamin solution (Sigma-Aldrich, St. Louis, MO, USA), 1% (w/v) sucrose, 0.05% MES, and 0.8% agar, pH 5.7 with KOH). Two-week-old Arabidopsis seedlings were transplanted into the soil (Supermix-A; Sakata Seed, Kanagawa, Japan) and grown for. 2–3 weeks in a long-day growth chamber with LED lights Instruments, Osaka, Japan) under a 16 h light/8 h dark photoperiod at 23 ◦ C

Inoculation Tests

Phytohormones Treatments

Pathogenic Behavior of the Rhizoctonia solani Isolates on Arabidopsis Leaves

Pathogenic Behavior of the Rhizoctonia solani Isolates on Arabidopsis Roots

Infectivity

Discussion