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.

Explanation

(a) It can be done only by genetic engineering
(b) Mutualism or symbiotic association.
(c) Microbe should be in close association with plant to provide mineral nutrition.
In subfamily Papilionatae of family Leguminosae, various plants contain symbiotic bacteria called rhizobium in their root nodules they act only when they are in close associtaion with root nodules.