| Fusarium head blight (FHB) is a devastating disease for barley ( Hordeum vulgare L.) produced in the Upper Midwest of the United States, which reduces yield and quality because the mycotoxin deoxynivalenol (DON) accumulates in infected grain. The development of improved cultivars with genetic resistance to FHB offers the greatest potential in controlling this disease, but genetic control of FHB reactions is complex. This study was conducted to determine the relationship between FHB resistance and morphological traits, such as lateral floret size, plant height, and heading date, which are associated with disease reactions. In order to determine if FHB severity is dependent on spike morphology in barley, 36 cultivars and Bowman backcross-derived lines with various spike morphologies were inoculated and screened for FHB resistance. The association between FHB severity and spike type was significant; however, the question of pleiotropy or tight linkage between barley spike morphology genes and FHB reaction remains unresolved. Another experiment identified quantitative trait loci (QTL) affecting FHB reaction, plant height, maturity, and DON accumulation in the doubled-haploid population of 140 lines derived from the 'Harrington'/'Morex' cross. A 107-marker skeletal map for this population was used to perform QTL analyses with the software package NQTL. In most environments, the QTL with the largest effect for all traits of interest were located on chromosome 2HL. Since coincident quantitative trait loci may be caused by use of a low-resolution map, close linkage, or pleiotropy, further investigation of 2HL is necessary. Adverse linkages in 2HL make development of resistant barley cultivars adapted to the Upper Midwest of the United States very challenging. The results obtained from this study contribute helpful information about the relationship between morphological traits and FHB reaction. |
