Working Document Series Open Access 2012 RUF-32482

Inheritance of Bacterial Leaf Blight Resistance in Crosses Involving Interspecific and Intraspecific Rice Genotypes

R. EdemaJ. LamoR.K. Lussewa

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Abstract

188 words

Bacterial leaf blight (BLB) of rice, caused by Xanthomonas oryzae pv. oryzae is a destructive disease prevalent in most rice growing countries. It is a serious problem under all managements, but especially in irrigated and high fertilizer input conditions, which are conducive to disease development. The disease causes reductions in crop yields as high as 80% and deterioration of grain quality under severe epidemics. Control of the disease through the use of chemicals is not cost effective or environmentally friendly for resource-constrained farmers. Use of resistant varieties is considered the only viable option. However, this requires prior information concerning the mode of inheritance of the BLB resistance trait. Some studies showed that resistance is a monogenic recessive trait, whereas in other studies it was found to be due to incomplete dominance, with preponderance of additive effect. In Ugandan rice populations, detection of epistatic effects on inheritance of BLB resistance and the resistance of “universally susceptible” IR24 to some local BLB pathotypes provides additional justification to dissect the nature of gene action and the magnitude of G x E in the new sources in order to guide breeding strategies.

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