Exploring the Rhizobial Interactions with Non-Nodulating Legume Gleditsia Triacanthos
Mentor 1
Gyaneshwar Prasad
Mentor 2
Laura Ketelboeter
Mentor 3
Sreevidya Sambukumar
Location
Union Wisconsin Room
Start Date
28-4-2017 1:30 PM
End Date
28-4-2017 4:00 PM
Description
Legumes are by far the largest contributors of biologically fixed N2 to terrestrial environments due to their symbiotic association with bacteria (rhizobia). Although nodulation is often considered to be a distinguishing characteristic of legumes, many legume species do not nodulate. However, non-nodulating legumes live in the same native environments as their nodulating "cousins" and yet have the same in planta N concentrations. In contrast to detailed understanding of rhizobial interactions during nodulation and nitrogen fixation, very little is known if the non-nodulating legumes can interact with rhizobia and if they can fix nitrogen. To answer this questions, we are utilizing Gleditsia triacanthos, (honey locust) that is native to USA and is widely used for timber and ornamental purposes. This study encompasses a multi-directional approach to better understand the relationship between G. triacanthos and rhizobial bacteria. Analysis of the roots of naturally growing honey locust revealed the presence of nodule-like structure and microscopic observations showed presence of bacteria in these structures. Further isolation and 16S rDNA sequencing identified the bacteria as different species of Rhizobium. In a complementary approach surface-sterilized seedlings of honey locust were inoculated with various strains of legume-nodulating rhizobium marked with β-glucuronidase (GUS) and/or Green Fluorescent Protein (GFP) and colonization was studied by histochemical GUS staining and microscopy. Further work is in progress to determine if the similarities/differences of these associations vis a vis nodulating legumes and whether rhizobial infection in G. triacanthos leads to nitrogen-fixing symbiosis.
Exploring the Rhizobial Interactions with Non-Nodulating Legume Gleditsia Triacanthos
Union Wisconsin Room
Legumes are by far the largest contributors of biologically fixed N2 to terrestrial environments due to their symbiotic association with bacteria (rhizobia). Although nodulation is often considered to be a distinguishing characteristic of legumes, many legume species do not nodulate. However, non-nodulating legumes live in the same native environments as their nodulating "cousins" and yet have the same in planta N concentrations. In contrast to detailed understanding of rhizobial interactions during nodulation and nitrogen fixation, very little is known if the non-nodulating legumes can interact with rhizobia and if they can fix nitrogen. To answer this questions, we are utilizing Gleditsia triacanthos, (honey locust) that is native to USA and is widely used for timber and ornamental purposes. This study encompasses a multi-directional approach to better understand the relationship between G. triacanthos and rhizobial bacteria. Analysis of the roots of naturally growing honey locust revealed the presence of nodule-like structure and microscopic observations showed presence of bacteria in these structures. Further isolation and 16S rDNA sequencing identified the bacteria as different species of Rhizobium. In a complementary approach surface-sterilized seedlings of honey locust were inoculated with various strains of legume-nodulating rhizobium marked with β-glucuronidase (GUS) and/or Green Fluorescent Protein (GFP) and colonization was studied by histochemical GUS staining and microscopy. Further work is in progress to determine if the similarities/differences of these associations vis a vis nodulating legumes and whether rhizobial infection in G. triacanthos leads to nitrogen-fixing symbiosis.
