Analysing the colonisation of inoculated cyanobacteria in wheat plants using biochemical and molecular tools

The modulation in physiological and metabolic attributes associated with colonisation by cyanobacteria in wheat has been little explored. In the present investigation, the performance of six selected cyanobacterial strains was evaluated with wheat (variety HD2687). The fresh weight of plants, measured after 2 weeks, exhibited a 30-60 % increase, while 14-40 % increase in plant dry weight was also recorded, as compared to uninoculated control. The nitrogen-fixing potential (expressed as acetylene-reducing activity or ARA) was 20-fold higher in the treatment involving inoculation of Anabaena laxa RPAN8 as compared to that in the uninoculated control. The inoculation of Calothrix sp. RPC1 brought about a more than 90 % increase in endoglucanase activity and root chlorophyll. Comparison of DNA fingerprints (highly iterated palindrome (HIP)-TG profiles) of wheat roots with those of corresponding pure cultures revealed a high degree of similarity, confirming the colonisation. Significant correlation of plant parameters with nitrogen-fixing potential and growth attributes and fingerprints of cyanobacteria from roots further illustrated the novelty of our results. This represents a first report on understanding hydrolytic enzyme-mediated colonisation of cyanobacteria on roots of wheat plants using plant growth parameters and DNA fingerprints. Such synergistic combinations of cyanobacterium and wheat can lead to savings of nitrogen and increased yields, besides being a prelude to generating nitrogen-independent wheat plants.