Phylogenetic relationships and pathogenicity of Colletotrichum acutatum isolates from grape in subtropical Australia

Abstract

The identity of Colletotrichum acutatum as the causal pathogen of grape ripe-rot, which causes yield loss and a bitter taint that lowers wine quality in Australian subtropical wine-grape regions, was confirmed using species-specific primers. Cultural, morphological and molecular methods (RAPD-PCR and sequencing of parts of the 5·8S-ITS regions and the β -tubulin-2 gene) were used to determine the phylogenetic relationships of Australian C. acutatum isolates from wine grapes and other horticultural crops. A combination of RAPD-PCR and β -tubulin-2 gene data showed that all wine-grape ripe-rot isolates from northern regions of New South Wales (NSW) and Queensland belong to a proposed new C. acutatum group (A9), together with isolates from Australian strawberry, mango, blueberry and olive. The 5·8S-ITS sequences for these grape pathogens were identical to published sequences for an isolate from Cyclamen (the Netherlands) and differed by 1 bp from isolates from Capsicum (Taiwan) and orange (Costa Rica). The grape ripe-rot isolates from the Shoalhaven Valley (southern NSW) were clustered within two other C. acutatum groups: A2 and A5. In vitro infection studies showed that Australian C. acutatum isolates from almond, blueberry, chilli, grape, mango, olive, strawberry and tomato were able to infect grape and could also infect blueberry and strawberry, indicating a lack of host specificity. This lack of host specificity, the genetic similarity with non-grape isolates, and the fact that many of the non-grape hosts were isolated from wine-growing regions, suggest the potential for cross-infection between grape and other horticultural crops.

Chilli anthracnose disease caused by Colletotrichum species

“…However, in other cases, identification can be complicated because of overlapping ranges of conidial morphology and variation in colony characteristics (Adaskaveg and Hartin, 1997). Correct taxonomic identification is important in disease management such as choosing appropriate fungicides (Whitelaw-Weckert et al, 2007). For instance, it could be seen in different responses of C. acutatum and C. gloeosporioides to benzimidazole-based fungicides (Peres et al, 2004).…”

“…Some Colletotrichum species respond differently to various control measures, e.g., C. acutatum was found to be moderately susceptible to the fungicide, benzimidazole, while C. gloeosporioides was highly susceptible (Peres et al, 2004). Correct and accurate identification will thus ultimately lead to more effective disease control and management, e.g., selecting appropriate fungicides, or long lasting resistant cultivars (Whitelaw-Weckert et al, 2007).…”

Epidemiology of cashew anthracnose (Colletotrichum gloeosporioides Penz.) in Mozambique

“…Fungal mycelia were then harvested from PDA cultures in laminar hood and total genomic DNA extracted using the DNeasy Plant Mini Kit (Qiagen Inc.) (Anon., 2004). For PCR amplification, species-specific primers from the ITS1 region of the ribosomal DNA gene (Ivey et al, 2004) CaInt2 (5'-GGC-GCCGGCCCCGTCACGGGGG-3') and CgInt (5'-GGCCTCCCGCCTCCGGGCGG-3') for C. acutatum and C. gloeosporioides respectively, were individually coupled with the universal and conserved primer ITS4 (Ivey et al, 2004;Whitelaw-Weckert et al, 2007 …”

Morphological and molecular identification of Colletotrichum acutatum from tomato fruit

“…Traditional identification and characterization of Colletotrichum species has relied primarily on differences in morphological features such as colony colour, size and shape of conidia and appressoria, growth rate, presence or absence of setae, and existence of the Glomerella teleomorph (Smith and Black, 1990;Gunnell and Gubler, 1992;Sutton, 1992). However, due to their morphological variability, the ample range of hosting crops, and wide variety of isolates, they are partially difficult to identify by traditional taxonomic methods, which must be complemented with molecular techniques (Whitelaw-Weckert et al, 2007). Construction of species-specific primers, especially from the ribosomal DNA internal transcribed spacer (ITS) region, has been proposed as the most efficient and reliable system for detection and differentiation of Colletotrichum spp.…”