Abstract

CHARACTERIZATION OF COLLETOTRICHUM SPECIES CAUSING BITTER ROT OF APPLES IN KASHMIR ORCHARDS

Gajendra Singh, Pushkar Choudhary, Rayees Ahmad, Rajveer Singh Rawat, Dr. Bhanwar Lal Jat*

Abstract

Morphology-based identification, as well as species-specific primer analyses, revealed that the Colletotrichum isolates sampled from bitter rot lesions in symptomatic apple from Kashmir orchards belong to two species complexes: the C. acutatum species complex and the C. gloeosporioz'des species complex. Multi-locus gene sequence-based identification using the TUB2 and GAPDH genes identified species within the C. acutatum species complex as C. fioriniae and C. nymphaeae, and species within the C. gloeosporioides species complex as C. siamense, C. theobromicola, and C. fructicola. Colletotrichumfioriniae is distinguished from the other species by the production of a red pigment in culture, and this enabled C. fz‘orinz‘ae to be recognized as the most abundant bitter rot species in Kentucky (approximately 70% of the total number of isolates). Pathogenicity to apple fruit differs between the two species complexes, as well as among the species within each species complex. The C. gloeosporioides species complex was more aggressive than the C. acutatum species complex, on average. Colletotrichum siamense was the most aggressive species among the five, causing larger and deeper lesions. The sensitivity of Colletotrichum species to thiophanate-methyl, myclobutanil, trifloxystrobin and captan was different, on average, between the two Species complexes, as well as among each species within each species complex. The C. acutatum species complex was more tolerant to tested fungicides compared to the C. gloeosporioides species complex. Among all five species, C. fioriniae was the most tolerant to the fungicides used in this study. Fingerprinting using RAPD analyses suggested that C. fopromoae represented a relatively homogenous population. Relatively diverse RAPD banding patterns were observed within species in the C. gloeosporioides species complex, indicating a potentially higher level of diversity.

Keywords: RAPD, Colletotrichum, PDB, RFLP, FDA, GAPDH and TUBZ.