The symbiotic effect of Piriformospora indica on induced resistance against bakanae disease in rice (Oryza sativa L.)

The root endophytic fungus, Piriformospora indica, colonizes roots of a large number of plant species including Cereals and Brasicaceae. There are several reports indicating that P. indica protects roots from different path- ogens. In the present study, rice plants were pre-inoculated with P. indica and were subsequently infected with Fusarium proliferatum, as the causal agent of root rot and crown rot (Bakanae) disease. The effects of P. indica on the protection of rice plants against F. proliferatum were evaluated. Transcription levels of some pathogenesis-related genes such as NPR1, PR1, PR4 and PR5, as well as two transcriptional factor genes namely WRKY62 and WRKY85 were quantified via quantitative real time PCR in rice roots. Pre-inoculated and challenged rice plants showed mild disease symptoms with two weeks delay compared to non P. indica colonized plants. Quantification of Fusarium in roots via q-PCR con- firmed the higher quantity of the fungi in non pre-inoculated plants. Expression analysis revealed a faster induction of pathogenesis related genes following F. proliferatum inoculation of pre-inoculated plants i.e. priming of these genes is a part of mechanism of P. indica induced systemic resistance.