First report of Rhizoctonia solani Kühn AG 2-2 LP in Zoyzia japonica Steud in Brazil

Abstract

The use of cultivated grasses in Brazil has grown by 40% between 2010 and 2015, and the species Zoysia japonica Steud, especially the cultivar ‘Esmeralda’, corresponds to 81% of the grass market in the country. The most important disease affecting zoysia grass, known as large patch, is caused by Rhizoctonia solani and occurs in the Brazilian lawns particularly during winter months. The aim of this study was to contribute to the identification and characterization of the anastomosis group of R. solani isolates from lesions typical of large patch collected from ‘Esmeralda’ grass at gardens and golf courses in the states of São Paulo and Bahia, Brazil. All 12 obtained isolates presented dark-brown colonies with aerial mycelial growth, multinucleated hyphae and absence of concentric zonation or sclerotia, and showed their greatest mycelial growth rate at 25°C. In pathogenicity experiments, except three out of R. solani isolates, reduced the growth of zoysia grass. Based on the analysis of sequences of the rDNA-ITS region, the isolates clustered with reference isolates of the anastomosis group AG 2-2 LP. Phylogenetic inference showed that the Brazilian isolates are grouped into two clades that shared the same common ancestral with 96% bootstrap. One of the clades includes only Brazilian isolates while the other one also includes American and Japanese R. solani isolates AG 2-2 LP. This is the first report and characterization of R. solani AG 2-2 LP in zoysiagrass in Brazil.

First occurrence of dsRNA in Rhizoctonia solani AG2-2 LP from turfgrass Zoysia japonica in Brazil / Primeiro relato de RNA dupla fita em Rhizoctonia solani AG2-2 LP, patógeno de Zoysia japônica no Brasil

“…The occurrence of several dsRNA segments in R. solani isolates from zoysiagrass is consistent with the ubiquitous presence of mycovirus in this fungus [18]. It was not possible to correlate dsRNAs segments with virulence, since in previous work, we found no significant difference in virulence among R. solani isolates [14]. The complex electrophoretic pattern could be due to the presence of segmented viral genomes, mixed infections or defective dsRNAs.…”

“…The isolates IBRS04, IBRS07, IBRS07S, IBRS11, IBRS15, IBRS16, IBRS18, IBRS19, IBRS20, IBRS21, IBRS22 and IBRS23 were collected from zoysiagrass lawns from cities in the state of São Paulo, Brazil during the winter. All isolates were characterized by Picarelli [14] and deposited in Micoteca Mario Barreto Figueiredo (MMBF), accredited in the World Federation for Culture Collection (WFCCregistration WDCM 942). The isolate IBRS07S was obtained from a sector of the isolate IBRS07.…”

“…Moreover, reports of hypovirulence associated with viral dsRNAs in R. solani AG 3 [6] and in R. solani AG1-IA [7] make mycoviruses promising candidates for biological control, which may be an effective strategy for controlling large patch disease, especially since it does not rely on the use of chemicals, ensuring safe contact between people and lawns. The aim of this work was thus to detect the presence of dsRNA viruses in R. solani AG2-2 LP infecting Brazilian zoysiagrass previously identified [14].…”