Nano-diagnostic technique for detection of rice pathogenic fungus Pyricularia oryzae

Abstract

Rice blast caused by Pyricularia oryzae is considered as one of the most dangerous diseases in Egypt and worldwide. The fungus can infect rice plants at any growth stage. P. oryzae can be transmitted from seeds to seedlings and increase the possibilities of spreading the disease and could cause epidemics, so that blast was referred to seed-borne disease. Current investigation aimed to develop an advanced technique or procedure that would allow reliable, reasonably fast and accurate detection of dangerous seed-borne fungal diseases such as P. oryzae in rice. The most common seed health tests including washing test (WT), blotter method (BM), washing after incubation, modified (WAI), deep freezing method (DF) and potato dextrose agar method (PDA) were applied for detecting seed-borne fungi from rice seeds. Among other fungi, the blast fungus P. oryzae was recorded only for three times from rice seed samples with very low frequency values of 1.0 and 1.5 in 2015 season using WT and WAI, respectively, and 2.0 in 2016 season using WAI. PCR has many beneficial characteristics that make it highly applicable for detecting P. oryzae in seeds. So that, side by side, PCR reaction was used for detecting and identifing P. oryzae to overcome the time consuming and inacuracy of the common seed heath tests. Metallic nanoparticles, silver and iron oxide nanoparticles were also involved to enhance DNA extraction which considered an important step in the PCR technology. Silver and Iron oxide nanoparticles were able to enhance the quantity and purity of DNA template for successful PCR assay. Preferably, seed health methods should be sensitive, specific, rapid, robust, inexpensive and simple to be applicable and fit for plant quarantine purposes. Many detection methods occur for different seed-borne pathogens, but, few of the minimum requirements for adequate seed tests were satisfied. In conclusion Nano based PCR method could be applied as an appropriate test for rapid detection of rice pathogenic fungus P. oryzae.