P-236 - Charcoal rot resistance screening: a cut stem method effective in sesame

Macrophomina phaseolina, the cause of charcoal rot, is one of the most problematic pathogens to sesame production globally, including in developing countries. One challenge to research in this area are the limitations of soil infestation when examining large numbers of varieties, or when non-destructive data collection is desired. Cut stem inoculation methods have been useful in other cropping systems such as soybean, though no work has been conducted on sesame to determine if this is a viable method of inoculation. The objective of this work was to determine if the cut stem method of inoculation is effective as a screening tool for plant response to M. phaseolina challenge. Varieties of sesame were planted in 26.5L pots in a nethouse and grown to at least 7 sets of true leaves. Plants were cut above the 7^th set of true leaves with a clean razor blade, and PDA culture plugs of M. phaseolina were applied to the freshly cut tips with a sterile pipette tip and snugged down. Progress of symptoms were measured every 7 days, as well as the total length of the plant from the cut tip to the base for normalization. The same varieties were grown in infested soil. Data from inoculated varieties were compared with those from plants grown in infested soil. Plants with the cut stem inoculation method had significant correlation values (p < 0.05) with scores of those grown in infested soil. The cut stem method provided a method suitable to provide symptom progression measures and high throughput screening, which would be helpful tools for future research.