Effect of Toxic Compounds of Exserohilum turcicum on Chlorophyll Content, Callus Growth and Cell Viability of Susceptible and Resistant Inbred Lines of Maize

Toxicity of toxic compounds in the culture filtrates of Exserohilum turcicum towards seed germination, inhibition of shoot and root growth, callus growth and on reduction in chlorophyll content and cell viability of maize was studied. There was no germination in unautoclaved extracts at 100% (undiluted) and 50% concentrations, whereas germination was normal at all the concentrations of autoclaved toxic compounds. Inhibition of root growth was higher compared with that of shoot growth in al! the test preparations of toxic compounds. Reduction in total chlorophyll and also chlorophyll a and b contents of disease resistant (KWTC-17) and susceptible (DK-4) inbreds occurred at 50, 25 and \0% concentrations of toxic compounds, with maximum reduction in the susceptible compared with the resistant inbred. Chlorophyll a was found to be more sensitive, showing 7.2% reduction in content in susceptible inbred even at 5% toxin concentration. Callus cultures/cell suspensions derived from coleotible nodes of DK-4 were more sensitive compared with that of KWTC-17 in all the test concentrations of toxic compounds. Callus growth of susceptible inbred DK-4 was inhibited by 32.7% compared with 15.31% of resistant inbred KWTC-17 at 5% concentration of toxic compounds. Ceil viability of resistant and susceptible inbreds was 62.0% and 20.2% at 10% toxic concentration, respectively. Spore germination assay with four fungal species or leaf puncture assay were not found useful.