Pathogenicity, anastomosis groups, host range, and genetic diversity of Rhizoctonia species isolated from soybean, pea, and other crops in Alberta and Manitoba, Canada

Abstract

Root rot is a common disease in soybean (<i>Glycine max</i>) and field pea (<i>Pisum sativum</i>), which restrain increased production in Canada. Sixty-seven isolates of <i>Rhizoctonia</i> were recovered from various diseased plants in Alberta, Canada along with three isolates from diseased soybean plants in Manitoba, Canada. According to their anastomosis behavior, 23 (32.9%) of the isolates were identified as anastomosis group (AG) 4 (AG4), 7 (10.0%) were AG2-1, 10 (14.3%) were AG2-2, 7 (10.0%) were AG5, 3 (4.3%) were AG-E and the AGs of the remaining 20 (28.6%) isolates could not be determined. Isolates belonging to AG4 produced typical symptoms of stem rot and root rot on seedlings of soybean and pea and were more aggressive than the AG2-1, AG2-2, AG5 and AG-E isolates. Selected isolates of AG4, AG2-1, AG2-2, AG5 and AG-E were to some degree able to infect common crops in Alberta, which included barley, canola, corn, faba bean, flax, lupin, lentil, pea, potato, soybean and wheat. The genetic variability among these isolates was evaluated using phylogenetic analysis based on the rDNA ITS sequences and inter-simple sequence repeat (ISSR) markers. For the ITS sequence analysis, a neighbour-joining tree was constructed using the PAUP program, which clustered the <i>Rhizoctonia</i> isolates into five groups (Groups I to V). However, no correlation was observed between AGs, locations, aggressiveness or host origins. For the ISSR analysis, 54 polymorphic ISSR patterns were identified, indicating a high level of diversity among the isolates.

Identification of Fusarium spp. Associated with Chickpea Root Rot in Montana

“…Fusarium proliferatum has been reported to cause vascular wilt in chickpeas from Cuba [57]. A recent Canadian study by Yu et al [58] showed that canola and leguminous crops were highly susceptible to F. proliferatum. At the same time, barley and wheat were partially susceptible, indicating a broad host range for this species.…”

“…Given that F. avenaceum has a broad host range and can infect small grain crops such as barley, wheat, and canola [19,40], alternative non-host crops for this aggressive species must be incorporated into crop rotation programs. Previous studies [50][51][52][53][54][55][56][57][58][59][60][61][62] highlighted the need for identifying sources of resistance to F. oxysporum f. sp. ciceri.…”

Overview and Management of the Most Common Eukaryotic Diseases of Flax (Linum usitatissimum)

“…Current classification systems divide individual, multinucleate R. solani strains into 13 different anastomosis groups (AGs), based on hyphal fusion, culture morphology, rDNAinternal transcribed spacer sequences and pathogenicity [80]. Divergent studies revealed that AG 1, AG 2-1, AG 2-2, AG 4, AG 9 and to a lower degree AG 5 are the most aggressive anastomosis groups inducing seedling blight and/or root rot symptoms on flax [28,[81][82][83][84][85][86][87]. Strains belonging to AG 3 only attack older plants, resulting in limited root rot [86], and AG 6 and AG 7 do not appear to be pathogenic [28].…”

“…Strains belonging to AG 3 only attack older plants, resulting in limited root rot [86], and AG 6 and AG 7 do not appear to be pathogenic [28]. The binucleate Rhizoctonia AG-E has also been isolated from older flax plants, which showed typical symptoms of root rot [85].…”

Assessment of Genetic Variability and Evolutionary Relationships of Rhizoctonia solani Inherent in Legume Crops

“…These diverse markers were utilized to evaluate and characterize the genetic variability and AGs of R. solani. Among these molecular markers, the sequence analysis of the rDNA ITS1-5.8S-ITS2 region stands out as a particularly potent tool for investigating genetic diversity and phylogenetic relationships within the anastomosis groups (AGs) and AG subgroups of R. solani [25][26][27][28][29][30][31][32][33][34]. The rationale is that all eukaryotic genomes contain these regions, and they are rapidly evolving and are surrounded by nucleotide sequences that are highly conserved.…”