PATHOGENIC VARIABILITY IN PYRICULARIA-GRISEA AT A RICE BLAST HOT-SPOTBREEDING SITE IN EASTERN COLOMBIA

Citation
Fj. Correavictoria et Rs. Zeigler, PATHOGENIC VARIABILITY IN PYRICULARIA-GRISEA AT A RICE BLAST HOT-SPOTBREEDING SITE IN EASTERN COLOMBIA, Plant disease, 77(10), 1993, pp. 1029-1035
Citations number
28
Categorie Soggetti
Plant Sciences
Journal title
ISSN journal
01912917
Volume
77
Issue
10
Year of publication
1993
Pages
1029 - 1035
Database
ISI
SICI code
0191-2917(1993)77:10<1029:PVIPAA>2.0.ZU;2-C
Abstract
Forty-five international races of Pyricularia grisea, representing all nine race groups, were identified in a ''hot spot' breeding site (San ta Rosa) in Colombia, with the largest number included in the IA group . The international race system did not fully describe the virulence s pectrum of the isolates, since several races could be further differen tiated into different pathotypes when local commercial cultivars were used as differentials. Compatibility was present in the pathogen popul ation for at least 13 known resistance genes and resistance sources te sted. Frequency of virulent phenotypes on the 42 cultivars tested rang ed from 0.0 to 0.86, with no cultivar susceptible to all isolates. The lowest compatibility frequencies were associated with combinations of resistance genes. It was unusual to recover isolates compatible with cultivars K-8, Peta, Ceysvoni, IR-42, Fujisaka 5, Fukunishiki, Zenith, and NP-125. No isolates were recovered that were compatible with the newly released cultivars Oryzica Llanos 4 and 5 developed at this site , and very few infected CICA 9. Analysis of the compatibility frequenc y of isolates recovered from commercial rice cultivars revealed a mark ed specialization for cultivar origin. Some cultivars were infected ma inly by isolates recovered from the same cultivar. Virulence factors w ere accumulated in the most virulent isolates, but no isolate was viru lent to all rice cultivars. Regardless, matching virulence for all res istance genes is already present in the pathogen population, indicatin g that new combinations of resistance factors and/or new resistance ge nes are needed. Rare compatibility with particular cultivars suggests that combinations of certain virulence genes may be associated with po or fitness. Differences in the distribution of virulence genes of P. g risea among and within cultivars support the feasibility of gene deplo yment strategies.