|Cooke, Louise - QUEENS UNIV., N. IRELAND|
|Black, L. - AVRDC, TAIWAN, ROC|
|Wang, T. - AVRDC, TAIWAN, ROC|
Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: December 15, 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, R.O.C., studies were conducted to help assess factors that may have contributed to recent epidemics in tomato crops. One-hundred forty-four isolates 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 the isolates recovered were of a new genotype. Furthermore, all these isolates were resistant to metalaxyl. Although the pathogen population was dominated by the 100:100:111 Gpi-genotype (characteristic of US-11), all the isolates were A1 mating types. 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.