Abstract
Twenty six isolates of Colletotrichum gloeosporioides from anthracnose infected mango fruits were isolated from different places of Tamil Nadu, India and these isolates were identified as C. gloeosporioides by Internal transcribed spacer (ITS) and species specific (CgInt) primers. The sensitivity of C. gloeosporioides isolates to benomyl fungicide were evaluated at five different concentrations viz., 0.5, 1, 2, 5, 10 mg/l through poisoned food technique and were expressed very less to highly sensitiveness to the fungicide. All the twenty six isolates were able to grow at the lowest concentration of 0.5 mg/l benomyl amended medium and the average mycelial growth was 70.70 mm at even days after inoculation. At the highest concentration of 10 mg/l benomyl, only two isolates viz., MCG 7 and 16 were able to grow with the mycelial diameter of 12.00 and 18.00 mm, respectively and 100% inhibition was found in the remaining isolates. In addition, benzimidazole sensitive and resistance β - tubulin gene sequences of TUB 1 and TUB2 were amplified from the benomyl sensitive isolates of C. gloeosporioides. The results indicated the differential resistance or sensitivity to benomyl fungicide against C. gloeosporioides and thereby allowed to identify the variability and diversity of the isolates on regional basis. Key words: Mango, C. gloeosporioides, benomyl sensitive, β - tubulin gene.
Highlights
Many diseases are affecting mango, of which anthracnose caused by Colletotrichum gloeosporioides (Penz.) Sacc is the most devastating disease and major constraint in production and export of mango
Twenty six isolates of Colletotrichum gloeosporioides from anthracnose infected mango fruits were isolated from different places of Tamil Nadu, India and these isolates were identified as C. gloeosporioides by Internal transcribed spacer (ITS) and species specific (CgInt) primers
Sanders et al (2000) evaluated 158 isolates of C. gloeosporioides and reported, 17.7% were resistant to benomyl with 8.5% highly resistant due to mutations in the β - tubulin gene using this information, C. gloeosporioides isolates from mango fruits collected in India were evaluated for benomyl sensitivity and mutations in the β - tubulin gene in the present study
Summary
Many diseases are affecting mango, of which anthracnose caused by Colletotrichum gloeosporioides (Penz.) Sacc is the most devastating disease and major constraint in production and export of mango. Several studies have demonstrated that benzimidazole resistance is associated with point mutations in codon 198 or 200 of the β-tubulin gene in various fungi, including Venturia inaequalis, Botrytis cinerea, Monilinia fructicola, C. gloeosporioides and Mycosphaerella fijiensis (Ma et al, 2003; Peres et al, 2004; Chung et al, 2006; Kim et al, 2007). Maymon et al (2006) reported that sequence analyses of the β-tubulin genes, TUB1 and TUB2, of five sensitive and five resistant representative isolates of C. gloeosporioides from Limonium spp. revealed that the benomyl resistant isolates had an alanine substitute instead of a glutamic acid at position 198 in TUB2. Partial βtubulin sequences from C. gloeosporioides isolates of mango were amplified (Albertini et al, 1999; Yarden and Katan, 1993) as a molecular tool for the identification of benzimidazole-resistant isolates of C. gloeosporioides. Sanders et al (2000) evaluated 158 isolates of C. gloeosporioides and reported, 17.7% were resistant to benomyl with 8.5% highly resistant due to mutations in the β - tubulin gene using this information, C. gloeosporioides isolates from mango fruits collected in India were evaluated for benomyl sensitivity and mutations in the β - tubulin gene in the present study
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