Question

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.

1. Can we artificially induce the property of nitrogen fixation in a plant – leguminous or non-leguminous?
2. What kind of relationship is observed between mycorrihiza and pine trees?
3. 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.

Answer 1

1. Yes, one can artificially induce the property of nitrogen fixation in a plant – leguminous or non-leguminous through genetic engineering which involves the introduction of specific genes to the host plant that synthesises nitrogenase enzymes.
2. Symbiotic relationship
3. Yes, it is necessary for a microbe to be in close association with a plant to provide mineral nutrition as seen in leguminous plants. Species of rod-shaped Rhizobium have such relationship with the roots of several legumes such as alfalfa, sweet clover, sweet pea, lentils, garden pea, broad bean, clover beans, etc. The most common association with roots is nodules. The nodule contains all the necessary biochemical components, such as the enzyme nitrogenase and leghaemoglobin. The enzyme nitrogenase is a Mo – Fe protein and catalyses the conversion of atmospheric nitrogen to ammonia.