Seven isolates of Colletotrichum gloeosporioides causing mango anthracnose were collected from Agri Export Zone (AEZ) of Andhra Pradesh and from Tamil Nadu (Cg1 to Cg7). They were identified to species by using species-specific Polymerase Chain Reaction (PCR) primers for a ribosomal Internal Transcribed Spacer (ITS) region and morphological characters. The isolates were evaluated for their pathogenic variability on mango seedlings and genetic diversity with molecular techniques like Random Amplified Ploymorphic DNA (RAPD) and Internal Transcribed Spacer-Restriction Fragment Length Polymorphism (ITS-RFLP). In pathogenicity, isolate Cg2 recorded maximum Percent Disease Incidence (PDI) followed by Cg7 and both were highly virulent (>40 PDI). Cg1, Cg6 and Cg3 were moderately virulent (>30-40 PDI) and Cg4 and Cg3 were less virulent (<30 PDI). In RAPD, the five random primers OPA-03, 04, 19, 20 and OPD-13 were used and the seven isolates were grouped into three main clusters.

Cluster I (Cg1 and Cg4), cluster II (IIa: Cg2 and Cg5; IIb: Cg3) and cluster III (Cg6 and Cg7). Clusters I and II have the genetic variability of 61%. Three clusters varied among themselves with a genetic variability of 84%. Out of five primers in RAPD, OPA 19 amplified two fragments of approximately 600 bp and 1400 bp for isolate Cg2 and one fragment of approximately 1300 bp for isolate Cg7. OPA 20 amplified 2700 bp fragment for Cg2 and 1400 bp for Cg7. These were unique fragments specific to highly virulent isolates Cg2 and Cg7. In ITS-RFLP, three enzymes RsaI, TaqI and PvuII produced uniform banding patterns for all isolates. However, enzymes HinfI and TruII differentiated the isolate Cg6 from others by unique banding pattern. The relationship between pathogenic variability and genetic diversity among the isolates of Colletotrichum gloeosporioides were discussed.

Mango (Mangifera indica L.), the "King of Fruits", is one of the most important commercial fruit crops and native to India and Southeast Asia. India is one of the leading producers of mango and shares around 56% of the total global production (Chadha, 2001). Andhra Pradesh ranks first in production and productivity among Indian states. To date, about 60 different diseases have been reported to be affecting mango, of which anthracnose caused by Colletotrichum gloeosporioides is an important destructive disease and major limiting factor in fruit production and export. All varieties of mango are reported to be susceptible to anthracnose. This disease is severe in most of the places and more severe where continuous rainfall, high temperature and high humidity prevail (Ann et al., 1994).

Genetic Diversity and Pathogenic Variability among Colletotrichum gloeosporioides Penz. Isolates: The Causal Agent of Mango Anthracnose,isolates, variability, genetic, Colletotrichum, anthracnose, production, primers, gloeosporioides, approximately, fragments, enzymes, banding, cluster, reported, pathogenic, Transcribed, diseases, amplified, export, evaluated, fragment, caused, global, characters, identified, humidity, affecting, moderately, Mangifera, morphological, pathogenicity