Sucrose metabolism in P. indica-nematode-plant interaction

The beneficial endophytic fungus Piriformospora indica colonizes roots of many plant species, including the model plant Arabidopsis thaliana, and promotes their growth, development and seed production as well as confers resistance to various biotic and abiotic stresses. For this service the endophyte withdraws carbohydrates from the host. There are indications that P. indica for its proper development requires simple sugar molecules such as hexoses glucose and fructose, however this still needs to be confirmed. Therefore, due to this apparent lack in the knowledge, in the course of this proposal changes in sugar metabolism caused by P. indica colonization in Arabidopsis roots will be analysed in detail. In addition, the impact of altered sugar levels caused by the fungus on development and parasitism of plant-parasitic cyst and root-knot nematodes will be determined. Hypothetically, both organisms require different sugar molecules as primary energy source (P. indica simple sugars; nematodes unprocessed sucrose) and it can be thus speculated that they may significantly affect each other. Moreover, the fungus colonization may also significantly reduce the susceptibility to nematodes, which could primarily be based on modified sugar metabolism. To test this hypothesis, first it will be checked whether the fungus specifically changes the expression of several sucrose synthase (SUS) and invertase (INV) genes, which are responsible for conversion of sucrose to glucose and fructose. Further, SUS and INV Arabidopsis mutants will be used to test the colonization efficiency of the fungus. In addition, an invertase activity assay as well a sugar pool analysis of plants colonized with P. indica will shed light on the changes in sugar household during this mutualistic interaction. Further, the systemic effects of P. indica on the parasitism of both cyst and root-knot nematodes in split-root system will be tested. Finally, several fungus-derived SUS and INV genes will be knockdown in P. indica in order to elucidate their role during plant colonization as well as their impact on nematode parasitism. The results obtained in the course of this proposal will significantly widen our knowledge about up to date largely unknown sugar metabolism in roots colonized with P. indica. Further, these newly gained details of the interaction between P. indica and its host plant could have promising potential for improving crop productivity and protection against plant- parasitic nematodes and other pests.

The beneficial endophytic fungus Serendipita indica colonizes roots of many plant species, including the model plant Arabidopsis, and promotes their growth, development and seed production as well as confers resistance to various biotic and abiotic stresses. For this service the endophyte withdraws carbohydrates from the host. There are indications that S. indica for its proper development requires simple sugar molecules such as hexoses glucose and fructose, however this still needs to be confirmed. Therefore, due to this apparent lack in the knowledge, in the course of this proposal changes in sugar metabolism caused by S. indica colonization in Arabidopsis roots will be analysed in detail. In addition, the impact of altered sugar levels caused by the fungus on development and parasitism of plant-parasitic cyst and root-knot nematodes will be determined. Hypothetically, both organisms require different sugar molecules as primary energy source (S. indica simple sugars; nematodes unprocessed sucrose) and it can be thus speculated that they may significantly affect each other. Moreover, the fungal colonization may also significantly reduce the susceptibility to nematodes, which could primarily be based on modified sugar metabolism. To test this hypothesis, first it will be checked whether the fungus specifically changes the expression of several sucrose synthase (SUS) and invertase (INV) genes, which are responsible for conversion of sucrose to glucose and fructose. Further, SUS and INV Arabidopsis mutants will be used to test the colonization efficiency of the fungus. In addition, an invertase activity assay as well a sugar pool analysis of plants colonized with S. indica will shed light on the changes in sugar household during this mutualistic interaction. Further, the systemic effects of S. indica on the parasitism of both cyst and root-knot nematodes in split-root system will be tested. Finally, several fungus-derived SUS and INV genes will be knockdown in S. indica in order to elucidate their role during plant colonization as well as their impact on nematode parasitism. The results obtained in the course of this proposal will significantly widen our knowledge about up to date largely unknown sugar metabolism in roots colonized with S. indica. Further, these newly gained details of the interaction between S. indica and its host plant could have promising potential for improving crop productivity and protection against plant-parasitic nematodes and other pests.