Rice blast disease which is caused by the filamentous ascomycetes Pyricularia
grisea is one of the most devastating diseases, showed high level of variability and
classified into various pathotype or races base on the infection pattern obtained on a set of
differential rice cultivars. However, an understanding of this phenomenon at the molecular
level is still lacking. Knowledge on the genetic and pathotypic diversity and structure of the
fungal population in the field is essential for plant breeders to determine the suitable host
resistance to be used. To study the basis of variability of blast pathogen, we analys is the
sequence-specific DNA that refer to pathogenesis of pathogen, i.e. Host-species specificity
(Pwl2) gene, Sterol delta 8à delta 7 isomerase (Erg2) gene, and Cutinase (Cut1) gene from
five field sites of the endemic rice blast disease, North Sumatera, West Sumatera, Bogor,
Lampung, and Sukabumi, respectively. The sequence-specific DNA of blast pathogen was
generated using a pair of specific primers corresponding to Pwl2, Erg2, Cut1 gene. Eight
haplotypes were detected in all of 230 isolates where 2.2% is haplotype A-000, 6.1%
haplotype B-001, 6.1% haplotype C-011, 60.9% haplotype D-111, 1.3% haplotype E-010,
5.2% haplotype F-110, 1.7% haplotype G-100, and 16.1% haplotype H-101, respectively.
Base on these data, different control strategies based on host resistance might be developed.
The phenotypic analysis indicated that seven major resistant genes were incompatible to
nine tested isolates. Those genes are Pik, Pik-h, Piz, Piz5, Pi1, Pi7(t) and Pik -m. Another
three resistant genes which are also effective are Pik-p, Pish, and Pi9 where they are just
compatible to one isolate and incompatible to the other isolates. Three resistant genes are
Piz-t, Pit, and Pi19 showed specific interaction to one of the tested isolates. The specific
interaction is incompatibility reaction between Piz-t gene and R-173Skb isolate (haplotype
D-111) and compatible to the others, while both Pit and Pi19 genes incompatible to 04-012
isolate (haplotype H-101) and compatible to the other isolates. |