Role of histone deacetylase inhibitors in androgenic callus induction of Oryza sativa sub indica, in sight into evolution and mode of action of histone deacetylase genes.

Background: The potential of paddy breeding has reached its pinnacle, and hybrids have been the principal research outcome. Hence, our hypothesis was based on improvising the callus induction efficiency of recalcitrant Oryza sativa sub. indica hybrids by intervening into their cellular functions like cell division and histone regulation for the production of doubled haploids, a better output compared to hybrids.

Methodology And Results: Insight into the mechanism of cell division is the foremost concern in altering the same and hence studies on evolution, expression and action of histone deacetylase and its 12 genes (9 HDA and 3 HD-tunin genes) were chosen in the hypothesis. Expression of HDA genes at three stages (anther dehiscence, 1st callusing and second callusing stages) with inhibitor (trichostatin-A) interventions indicated 1st callusing stage as the most important in influencing callus induction and also the genes HDA19, 6, 15 and 5 were the most important. TSA alone had a significant impact on the regulation of the genes HDT 702, HDA19, HDA9, and HDA6. Higher expression of HDA19 and HDA6 was involved in maximizing callus induction; HDA15 had an antagonistic expression compared to HDA19/6 and might be involved in chlorophyll regulation during regeneration. Results of evolutionary analysis on histone deacetylases indicated a long and single lineage of origin denoting its importance in the basic cellular functions. The tubulin deacetylation gene HDA5, which was exclusively found in dicotyledons, had a recent evolutionary history only from terrestrial plants, and also had significant conservation in its motifs and NLS region.

Conclusion: By combating the recalcitrant nature of Indica cultivars, molecular editing on a combination of HDA genes will enhance the callus induction and regeneration efficiency of the next generation of doubled haploids, therby improving the total yield.