BGS 130, Early maturity 10, eam10

Early maturity sp = easp (10).

Monofactorial recessive (10).
Located in chromosome 3HL (10); eam10.m is about 2.0 5.8 cM from the Est1-Est4 (Esterase 1, Esterase 4) locus (10); about 5.8 cM distal from RFLP marker Xmwg546 (1); eam10.m is associated with SNP marker 1_1516 (position 249.75 cM) in 3H bin 16 of Bowman backcross-derived line BW284 (4); at the position of SNP marker 2_1500 [171.64 (252.98) cM] (2), in 3H bin 16.

In winter nurseries at Cuidad Obregón, Sonora, Mexico and Davis, California, USA, plants of Super Precoz 2H head about 11 days earlier than lines with the genes eam7.g or eam8.k for photoperiod insensitivity from Atsel and Sv Mari, respectively (10). The eam10.m gene appears to suppress expression of the eam7.g and eam8.k genes (10). Plants expressing eam10.m become chlorotic (yellow green) under photothermal stress. Zeaxanthin increased at the expense of chlorophyll and other pigments (9). The chlorotic appearance was similar to that observed in plants homozygous for other recessive genes for early maturity (eam7, eam8, and eam9) (3, 8, 9). Plants in the Bowman eam10.m line, BW284, headed one to three days earlier than Bowman under long days and about 12 days earlier under short days (7). BW284 plants were slightly shorter and had two to three fewer kernels per spike (7). Rate of stem elongation was accelerated in eam10 mutants, but the timing of meristem development closely followed that of Bowman (2). The candidate gene underlying the eam10 locus was reported to be Hvlux1, an ortholog of the Arabidopsis circadian gene LUX ARRHYTHMO. Of the sixteen polymorphic haplotypes of HvLUX1 characterized in accessions, most were present in wild barley (Hordeum vulgare subsp. spontaneum) (2). Campoli et al. (2) also demonstrated that eam10 caused circadian defects and interacts with the strong photoperiod response gene Ppd-H1 (Eam1) to accelerate flowering under both long- and short-day conditions.

Present in Super Precoz 2H (PI 527381) from Russia (9), but originating probably as an induced mutant in MC20 (5, 6, 9).

eam10.m in Super Precoz 2H (PI 527381) plus a dominant maturity enhancer ( 6, 8, 9); eam10.m in Amber Nude (GSHO 2505) without the enhancer (6).

eam10.m in Super Precoz 2H (GSHO 2504); eam10.m in Amber Nude (GSHO 2505); eam10.m from Super Precoz in Bowman (PI 483237)*4 (GSHO 3421); eam10.m from Super Precoz in Bowman*5 (BW284, NGB 20568); eam10.m from Amber Nude in Bowman*3 (BW283, NGB 20567).

1. Börner, A., G.H. Buck-Sorlin, P.M. Hayes, S. Malyshev and V. Korzun. 2002. Molecular mapping of major genes and quantitative trait loci determining flowering time in response to photoperiod in barley. Plant Breed. 121:129-132.
2. Campoli, C., A. Pankin, B. Drosse, C.M. Casao, S.J. Davis, and M. von Korff. 2013. HvLUX1 is a candidate gene underlying the early maturity 10 locus in barley: phylogeny, diversity, and interactions with the circadian clock and photoperiodic pathways. New Phytologist 199:1045-1059.
3. Dormling, I., and Å. Gustafsson. 1969. Phytotron cultivation of early barley mutants. Theor. Appl. Genet. 39:51-61.
4. 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.
5. Favret, E.A. 1972. El mejoramiento de las plantas por induccíon de mutaciones en latinoamerica. p. 49-59. In Induced Mutations and Plant Improvement. Int. Atomic Energy Agency, Vienna.
6. Favret, E.A., and G.S. Ryan. 1966. New useful mutants in plant breeding. p. 49-61. In Mutations in Plant Breeding. Int. Atomic Energy Agency, Vienna.
7. Franckowiak, J.D. (Unpublished).
8. Gallagher, L.W. (Unpublished).
9. Gallagher, L.W., A.A. Hafez, S.S. Goyal, and D.W. Rains. 1994. Nuclear mutations affecting chloroplastic pigments of photoperiod-insensitive barley. Plant Breed. 113:65-70.
10. 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.

L.W. Gallagher and J.D. Franckowiak. 1997. Barley Genet. Newsl. 26:166.

J.D. Franckowiak. 2007. Barley Genet. Newsl. 37:226-227.
J.D. Franckowiak. 2014. Barley Genet. Newsl. 44:86-87.