Do phylloplane microfungi influence activity of Rubisco and Carbonic anhydrase

Abstract

Ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco; EC 4.1.1.39) and Carbonic anhydrase (EC 4.2.1.1) are key enzymes of photosynthesis in plants. Microfungi colonizing leaf surface are known to affect photosynthesis but their influence on chloroplast physiology is not well understood. The present study aimed at possible effect of phylloplane microbes on activity of two key enzymes in chloroplast. The activity of Rubisco and Carbonic anhydrase was estimated in aseptically raised tomato and barley plants treated with metabolites of Fusarium oxysporum and Aspergillus niger which were dominant phylloplane microfungi. The activity of Carbonic anhydrase and Rubisco was significantly enhanced on application of fungal metabolites, either singly or in combination. Both the metabolites could significantly increase the activity of Rubisco and Carbonic anhydrase within 72 h of treatment in both tomato and barley. The effect was more pronounced when the fungal metabolites were sprayed in combination, thereby indicating their cumulative positive effect on the plants. However, the metabolite effect was reduced if the plants were pre-infected with their respective pathogens. The study highlights the critical relationship of phylloplane microflora with functioning of these two chloroplast enzymes in higher plants. The application of these metabolites, either singly or in combination in the host plants demonstrated a positive correlation between rubisco and carbonic anhydrase.