| | Breeding for resistance to Fusarium head blight (FHB) in barley, Hordeum vulgare, has involved introductions from many countries. Genetic factors for FHB resistance have been located in chromosome 2H, but this region also contains genes for early heading in response to long days. The early maturity genes (Eam) play a key role in adaptation of barley to various environments. Several Eam genes were backcrossed into Bowman (a spring, two-rowed cultivar) to study photoperiod responses in one genetic background. The long-day sensitive genes included: Eam1 (located in chromosome 2HS) in wild and winter barleys, Eam6 (chromosome 2H near the centromere) in Midwest six-rowed spring barley, and Eam11 [2HL near the six-rowed spike 1 (vrs1) locus] in European two-rowed barley. The short-day sensitive genes included: Eam5 [5HL near the rough awn 1 (Raw1) locus] in Indian and East Asian spring barleys, eam7 (6HS) in the Atsel mutant of Atlas, eam9 (4HS) in Chinese and Japanese cultivars, and eam10 (3HL) in Super Precoz 2H from Russia. The day-length neutral gene eam8 (1HL) was obtained from Kinai 5 and Early Russian and as ert-o and mat-a mutants in Swedish cultivars. The Eam genes show complex interactions with each other, with spring growth habit genes (sgh1, Sgh2, and Sgh3), and with the semidwarf 1 (sdw1) gene. Examples of spring barley cultivars having unusual combinations of maturity genes are Baronesse (eam11 and Eam5), Conlon (Eam11 and Eam6), and Steptoe (eam11, Eam1, plus winter growth habit). Utilization of early maturing Chinese cultivars as a source of FHB resistance is difficult because they contain combinations of maturity genes such as Eam1, Eam5, eam9, plus sdw1.
Jerome D. Franckowiak, Guotai Yu, and Nadejda Krasheninnik
Department of Plant Sciences, North Dakota State University, Fargo, ND 58105, USA
Presented at the 3rd Canadian Barley Symposium, June 19-20, 2003 |
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