Molecular genetic variability of Italian binucleate <Emphasis Type="Italic">Rhizoctonia</Emphasis> spp. isolates from strawberry |
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| Authors: | Luisa M Manici Patrizia Bonora |
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| Institution: | (1) Agriculture Research Council (C.R.A.) – I.S.C.I, Via di Corticella 133, Bologna, 40129, Italy |
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| Abstract: | Fifty-eight binucleate Rhizoctonia isolates were collected over six years from strawberry plants displaying symptoms of black root rot in Italy. Almost all
isolates were able to produce necrosis on strawberry roots, most of them also showed this ability on faba bean and, with lower
frequency, on a crucifer and a cereal crop used in rotation with strawberry in Italy. The sequence alignment of Internal Transcribed
Spacer (ITS) regions of 51 binucleate Rhizoctonia were analyzed and compared with a set of eight sequences representative of Rhizoctonia isolate Anastomosis Groups (AG) already found to be pathogenic on strawberry (AG-A, AG-G, AG-I and AG-F). The neighbour-joining
tree, based on ITS region sequences, divided Italian strawberry Rhizoctonia isolates into two main clusters corresponding to AG-A and AG-G. The results were confirmed by hyphal anastomosis tests. The
clustering obtained with the phylogenetic tree was also confirmed using PCR-Restriction Fragment Length Polymorphism of 28S
rDNA to compare some isolates, defined as AG-A and AG-G on the basis of ITS region sequence analysis, with representative
AG isolates pathogenic on strawberry. The AG-A and AG-G Rhizoctonia spp. were widespread in Italian strawberry-growing areas, although with different relative frequencies: AG-G was most frequent
in northern (latitude 44°N) and AG-A in southern (latitude 39–40°N) Italy. Analysis of MOlecular VAriance, based on geographic
location, showed that Rhizoctonia molecular variations between northern and southern Italy accounted for 36.6% of the total, but most of the variations (61%)
occurred within each of the four geographical regions from where the isolates originated. |
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| Keywords: | Black root rot Fragaria × ananassa ITS region Nucleotide sequence |
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