Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 9/21/2001
Publication Date: N/A
Technical Abstract: In recent years, Phytophthora infestans, the causal agent of late blight, has caused severe epidemics on potatoes in many parts of the world. Although late blight is endemic in Taiwan, studies were conducted to help assess factors that may have contributed to recent epidemics in potato and tomato crops. Numerous isolates of P. infestans from infected tomatoes in Taiwan have been collected and maintained by the Asian Vegetable Research and Development Center since 1991 in connection with its late blight resistance breeding program. Of these isolates, 144 were selected and characterized in terms of allozymes genotypes (glucose phosphate isomerase [GPI] and peptidase [Pep]), mating type, mitochondrial haplotype, pathotype and metalaxyl resistance. Genotype characterization of the isolates showed that a new genotype appeared in the 1998 collection and by 2000 all of the isolates recovered were of a new genotype to Taiwan. Furthermore, all of these isolates were resistant to metalaxyl. By analyzing these isolates for genetic and phenotypic diversity, it could be concluded that there has been a dramatic shift in P. infestans populations in Taiwan and it is representative of new pathogen populations that are currently prominent in many countries.