We find that Rhizobium forms nodules on the roots of leguminous plants. Also, Frankia another microbe forms nitrogen-fixing nodules on the roots of non-leguminous plant Alnus.
(a) Can we artificially induce the property of nitrogen fixation in a plant-leguminous or non–leguminous?
(b) What kind of relationship is observed between mycorrhiza and pine trees?
(c) Is it necessary for a microbe to be in close association with a plant to provide mineral nutrition? Explain with the help of one example.
Ans.
(a) Scientists have tried to induce the property of nitrogen fixation in leguminous and non- leguminous plants through genetic engineering by transforming the nitrogen fixation genes from the bacteria into the plants. But the experiments have shown an exceptionally low success rate, and no viable alternative to natural nitrogen fixation is available.
(b) It is a mutual or symbiotic relationship.
(c) Yes, it is necessary for a microbe to be in close association with a plant to provide mineral nutrition. For example, we can illustrate the example of the symbiotic relationship between Rhizobium and leguminous plants. Rhizobium is a bacterium which is found in the root nodules of leguminous plants. The root provides shelter and food to the bacterium, and in return, the bacterium helps in nitrogen fixation in soil.