BGS 252, Early maturity 7, eam7

Early heading = ec (9).

Early maturity 7 = ea7 (8).

Monofactorial recessive (5, 8).
Located in chromosome 6HS (9); eam7.g is about 0.5 cM from the rob1 (orange lemma 1) locus (8); eam7.g is about 3.0 cM from the centromere (7); eam7.g is near the centromere and between markers mwg2264 and mwg916 (10); eam7.g is associated with SNP markers 2_0886 to 1_0978 (positions 3.28 to 156.09 cM) in 6H bins 01 to 06 of the Bowman backcross-derived line BW288 (1); eam7.g is associated with homozygous SNP markers 2_0886 to 2_0291 (positions 3.28 to 81.35 cM) in 6H bins 01 to 06 of the Bowman backcross-derived line BW287 (1), likely in 6H bin 05.
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Under short-day conditions in California, USA, plants with the eam7.g mutant bloomed about 4 weeks before California Mariout, produced relatively few tillers, and were fine stemmed and relatively short. Differences were less pronounced under long-day conditions (8). Mutants were partially insensitive to photoperiod and have a vernalization requirement (9). Under long-day conditions, segregates expressing the eam7.g gene were difficult to identify (6). The differences in heading dates for Atsel [Eam1.a (Early maturity 1) plus eam7.g] and Betzes (Eam1 and eam7) were 55 and 18 days under short and long days, respectively (10). When the Eam1.a (Early maturity 1) gene is not present, eam7.g plants headed 10 to 14 days earlier than Bowman in nurseries at Yuma, Arizona, USA, but only 3 to 5 days earlier at Fargo, North Dakota, USA (2). The Eam1.a gene present in California, Mariout apparently interacts with the eam7.g allele under short-day conditions to cause extreme earliness (2). The Bowman backcross lines for eam7.g, BW287 and BW288, were 4 to 10 days earlier than Bowman under short days, but no differences were observed under long days (2). The HvCO7 (Hordeum vulgare CONSTANS 7) gene was located on the same chromosome arm as eam7 gene (5).

A spontaneous mutant in Atlas (PI 539108) identified as Atsel (CIho 6250) (3); present in male sterile Club Mariout/6*California Mariout (PI 527380) (3, 9).

eam7.g in BC6 California Mariout (GBC326, GSHO 579) (4, 8); eam7.n (Ea1), eam7.o (Ea2), eam7.p (Ea3) in Chikurin Ibaraki 1 (OUJ069, CIho 7370) (11).

eam7.g in BC6 California Mariout (GSHO 579); eam7.g in Bowman (PI 483237)*3 (GSHO 2068, BW288, NGB 20572), eam7.g in Bowman*2 (BW287, NGB 20571).

1. Druka, A., J. Franckowiak, U. Lundqvist, N. Bonar, J. Alexander, K. Houston, S. Radovic, F. Shahinnia, V. Vendramin, M. Morgante, N. Stein, and R. Waugh. 2011. Genetic dissection of barley morphology and development. Plant Physiol. 155:617-627.
2. Franckowiak, J.D. (Unpublished).
3. Gallagher, L.W. (Unpublished).
4. Gallagher, L.W., K.M. Soliman, and H. Vivar. 1991. Interactions among loci conferring photoperiod insensitivity for heading time in spring barley. Crop Sci. 31:256-261.
5. Griffths, S. R.P. Dunford, G. Coupland, and D. A. Laurie. 2003. The evolution of CONSTANS-like gene families in barley, rice, and Arabidopsis. Plant Physiol. 131:1855-1867.
6. Kasha, K.G., D.E. Falk, and A. Ho-Tsai. 1978. Linkage data with genes on chromosome 6. Barley Genet. Newsl. 8:61-65.
7. Kramer, H.H., and B.A. Swomley Blander. 1961. Orienting linkage maps on the chromosomes of barley. Crop Sci. 1:339-342.
8. Ramage, R.T. 1962. Genetic and cytogenetic studies of barley. Barley Newsl. 6:67.
9. Ramage, R.T., and C.A. Suneson. 1958. A gene marker for the g chromosome of barley. Agron. J. 50:114.
10. Stracke, S., and A. Börner. 1998. Molecular mapping of the photoperiod response gene ea7 in barley. Theor. Appl. Genet. 97:797-800.
11. Ukai, Y., and A. Yamashita. 1981. Early mutants of barley induced by ionizing radiation and chemicals. p. 846-854. In M.J.C. Asher, R.P. Ellis, A.M. Hayter, and R.N.H. Whitehouse (eds.) Barley Genetics IV. Proc. Fourth Int. Barley Genet. Symp. Edinburgh. Edinburgh Univ. Press, Edinburgh.

C.R. Burnham. 1971. Barley Genet. Newsl. 1:155. Early heading, ea7.

J.D. Franckowiak and L.W. Gallagher. 1997. Barley Genet. Newsl. 26:233.

J.D. Franckowiak. 2011. Barley Genet. Newsl. 41:123-124.

J.D. Franckowiak. 2015. Barley Genet. Newsl. 45:118-119.