Biological characteristics and metabolic phenotypes of different anastomosis groups of Rhizoctonia solani strains

Rhizoctonia solani is an important plant pathogen worldwide, and causes serious target spot disease in tobacco in the last five years. This research studied the biological characteristics of four different anastomosis groups (R. solani AG-3, R. solani AG-5, R. solani AG-6, R. solani AG-1-IB) of R. solani from tobacco, and analyzed the metabolic phenotype differences of these strains using metabolic phenotype technology. The results showed that the suitable temperature for mycelial growth of four anastomosis group strains were all from 20 to 30 {degrees}C, and for sclerotia formation were from 20 to 25 {degrees}C. Under different lighting conditions, R. solani AG-6 strains produced the most sclerotium, followed by R. solani AG-3, R. solani AG-5 and R. solani AG-1-IB. All strains had strong oligotrophic survivability, and can grow on water agar medium without any nitrutions. They exhibited three types of sclerotia distribution form, including dispersed type (R. solani AG-5 and R. solani AG-6), peripheral type (R. solani AG-1-IB), and central type (R. solani AG-3). They all presented different pathogenicities in tobacco leaves, with the most virulent was noted by R. solani AG-6, followed by R. solani AG-5 and AG-1-IB, finally was R. solani AG-3. R. solani AG-1-IB strains firstly present symbtom about inoculation. Metabolic fingerprints of four anastomosis groups were different to each other. R. solani AG-3, AG-6, AG-5 and AG-1-IB strains efficiently metabolized 88, 94, 71 and 92 carbon substrates, respectively. Nitrogen substrates of amino acids and peptides were the significant utilization patterns for R. solani AG-3. R. solani AG-3 and AG-6 showed a large range of adaptabilities and were still able to metabolize substrates in the presence of the osmolytes, including up to 8% sodium lactate. Four anastomosis groups all showed active metabolism in environments with pH values from 4 to 6 and exhibited decarboxylase activities. One-sentence summaryRhizoctonia solani strains from different anastomosis groups have a different adaptability to habitats.