Field reaction to Sclerotinia blight among transgenic peanut lines containing antifungal genes

Peanut (Arachis hypogaea L.) is susceptible to many diseases. In the southwestern USA and other regions where peanut is grown, diseases caused by fungi are a major threat to profitable production. Transgenic peanut lines possessing fungal resistance genes offer an alternative to traditional resistance and fungicide application in managing fungal diseases. Thirty-two transgenic peanut lines containing antifungal genes (a rice chitinase and/or an alfalfa glucanase) were evaluated for their reaction to Sclerotinia blight caused by Sclerotinia minor Jagger in small field plots (6.1 by 7.6 m) for 3 yr. Peanut lines were arranged in a complete randomized block design with three replications. Disease incidence was recorded throughout the growing season and data were analyzed for statistical significance. Over the 3-yr period, average disease incidence for the most resistant lines-188, Southwest Runner, 416, 540, and 654-was 0.0, 1.0, 10.0, 14.0, and 16.0%, respectively. The cultivar Okrun was most susceptible with an average disease incidence of 58.0%. All other lines had varying degrees of resistance but averaged at least 15.5% less disease than Okrun over the 3-yr period. Transgenic peanut lines with partial resistance to Sclerotinia blight were identified which may be useful in traditional breeding programs for fungal resistance.