A rapid and specific detection method for blast infection caused by Magnaporthe grisea in Setaria italica.

摘要

DNA samples isolated from infected and healthy leaves of Setaria italica plants raised in Kerala, India, after inoculation with M. grisea were subjected to PCR amplification. The primers pfh2a and pfh2b were used, which allow amplification of a 687-bp fragment of the pot2 transposon found in M. grisea causing blast of perennial ryegrass in the USA. The results showed that the new primers in a single amplification amplified the pot2 elements in the blast fungus in infected leaves. The infection was in the form of only one blast lesion. However, the primers failed to amplify DNA from uninfected or healthy S. italica and rice leaves showing multiple leaf blast lesions caused by inoculation with rice strains of M. grisea. Pot2 is present in rice- and non-rice-infecting isolates of M. grisea in equal copy number. However, the primer pair chosen for this protocol amplified a 687-bp region (from base pair 1055 to 1741) of the total Pot2 element for the specific detection of only the non-rice strains of M. grisea. The PCR results were reproducible for amplification of the 687-bp fragment in Setaria-infecting M. grisea, suggesting that this amplified region is common to isolates infecting foxtail millet and perennial ryegrass. This rapid detection procedure can be concluded within 3-4 h..