Cross-infection potential of genetic groups of Colletotrichum gloeosporioides on tropical fruits.
Alahakoon P. W., Brown A. E., Sreenivasaprasad S.
Author Affiliation: Department of Applied Plant Science, Queen's University of Belfast, Belfast, UK.
Physiological and Molecular Plant Pathology 44 : 93-103
Abstract : Cross-inoculation experiments demonstrated variation in the level of host preference among C. gloeosporioides [Glomerella cingulata] isolates from 7 tropical fruit crops and also variation in the susceptibility of the hosts. In general, isolates were much more pathogenic on leaves of the original host than on those of alternative crops. Isolates from avocado, durian (Durio zibethinus) and mango showed the greatest degree of host preference while isolates from mangosteen (Garcinia mangosteen [G. mangostana]) and pini jambu (Syzygium jambos) were the most pathogenic on alternative crops. Avocado, mango and rambutan (Nephelium lappaceum) were the most susceptible and mangosteen and pini jambu were the least susceptible to G. cingulata isolates from the other crops. The extent of cross-infection appeared dependent on inoculum density. Molecular markers based on restriction fragment length polymorphisms (RFLPs) in ribosomal DNA (rDNA), mitochondrial DNA (mtDNA) and random amplified polymorphic DNA (RAPD) enabled genetic grouping of the G. cingulata isolates. In some instances, isolates from different hosts, e.g. 2 of the avocado isolates, all 3 durian isolates and 1 rambutan isolate, had identical rDNA and very similar mtDNA banding patterns (category 3) indicating a common ancestry, but differed in their host preference, implying adaptation to different crops.