Role of Arbuscular Mycorrhizhal Fungi in Rice - Root Pathogens Interactions

Application of arbuscular mycorrhizal fungi (AMF) inoculum has been popular to increase the yield of rice plants by not just facilitating the nutrient uptake but also protecting against pathogens. Root knot nematode and parasitic plant, Striga are both serious pests in crops and it has been reported that AMF can protect against these pests in many crops. However studies evaluating cultivar differences in AMF colonization rates and the impact of AMF on root parasites are lacking in rice. Experiments were conducted to evaluate the influence of AMF (Rhizophagus intraradices) colonisation on infection of Meloidogyne graminicola and Striga (Striga hermonthica (Del.) Benth.), in two rice (Oryza sativa) cultivars, Azucena and Bala differing in susceptibility to these pests. AMF colonization rate was higher in Azucena (9.75%) than Bala (5.5%) and was reduced by nematode infection. Inoculation of AMF reduced the nematode gall numbers by 65-95% depending on cultivar and experiment, and reduced nematode reproduction success. Similarly, AMF colonisation was higher in both cultivars when Striga was absent. Numbers of Striga germinated were higher when AMF was absent. Until 42 DAS, in both cultivars, AMF reduced the numbers of Striga germination and the difference was more prominent in Bala than Azucena. This study emphasises that genotypic differences in AMF colonization rate exist in rice, highlights the potential of using biocontrol to reduce nematode and Striga infection in rice as shown in other crops and opens up an opportunity to explore rice-mycorrhiza- root pathogen interactions at the molecular level.