Detection of Magnaporthe grisea in infested rice seeds using polymerase chain reaction.
OBJECTIVE
To develop a diagnostic assay based on polymerase chain reaction for the detection of Magnaporthe grisea from infested rice seeds.


RESULTS
Primers were designed based on the nucleotide sequence of the mif 23, an infection-specific gene of M. grisea. The primers amplified target DNA from genetically and geographically diverse isolates of the pathogen. The lowest concentration of template DNA that led to amplification was 20 rhog. No PCR product was detected when DNA from other fungi was used, indicating the specificity of the primers. With this PCR based seed assay, M. grisea was detected in rice seedlots with infestation rates as low as 0.2%.


CONCLUSIONS
The PCR detection of M. grisea is simple, rapid, specific, sensitive and suitable for the routine detection of the pathogen in infested seeds.


CONCLUSIONS
Introduction of the blast fungus into new areas where it has not been previously recorded could be avoided by the detection of infested seedlots. A PCR-based seed assay could facilitate risk assessment of naturally infested rice seeds; help design management programs and optimize fungicide use.
Chadha
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Nuclear Agriculture and Biotechnology Division, Bhabha Atomic Research Centre, Mumbai, India. schadha@barc.ernet.in
Gopalakrishna
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T
D004271:DNA, Fungal / Q000032:analysis; D020082:Magnaporthe / Q000302:isolation & purification*; D009181:Mycoses / Q000175:diagnosis*; D012275:Oryza / Q000382:microbiology*; D010935:Plant Diseases / Q000382:microbiology*; D016133:Polymerase Chain Reaction / Q000379:methods; D012639:Seeds / Q000382:microbiology; D012680:Sensitivity and Specificity
D004271:DNA, Fungal