Coordinator's report: Chromosome 3
T. Konishi
294 Okado, Mabi-cho, Kibi-gun, Okayama 710-13, Japan.

In the first issue of Barley Genetics Newsletter (1971), the current linkage map of chromosome 3 contained only 19 loci for visible characters, ranging from als on the short arm to xs on the long arm of the chromosome. The number of loci on chromosome 3 gradually increased up to 65, although around a half of them were not located definitely (Søgaard and Wettstein-Knowles 1987). Recently, more than 100 markers are located on two new linkage maps of chromosme 3 presented by both groups of Germany (Graner et al. 1993) and NABGMP (Kleinhofs et al. 1993).

During a quarter of a century after the first issue of BGN, a remarkable change of linkage map of chromosome 3 was made to reverse between the short arm and the long one by means of Giemsa N-banding technique to barley telotrisomics, locating xs on the short arm and als on the long arm of chromosome 3 (Singh and Tsuchiya 1982). The linkage map of the long arm has been developed from als to the distal end step by step, after assignments of new loci. Namely, mapping of cu2 contributed to elongate 46.2 cM from als (Konishi et al. 1984), and further Est4 extended 26 cM from cu2 (Konishi and Matsuura 1987). Meanwhile, xs still remains as a tentatively terminal locus on the short arm. Compared with the long arm of chromosome 3 in the NABGMP Steptoe x Morex maps, the short arm does not contain so many molecular markers, possessing a large gap of 28.1 cM (Kleinhofs et al. 1993). The similar situation can be observed in the RFLP-map of chromosome 3 produced from Igri x Franka (Graner et al. 1993). Most of the markers scattered on the long arm of the chromosome, while the short arm has the larger gap of 52.8 cM. As the short/long arm ratio is 0.7 (Singh and Tsuchiya 1982), more visible and molecular markers have to occupy in the short arm of chromosome 3.

Recently, four isozyme loci are located on the long arm of chromosome 3. The CepB gene for cysteine endopeptidase is linked to the Ndh2 gene encoding NADH diaphorase, and Ndh2 is linked with the seedling esterase complex (Est1, Est2, and Est4) situated near the distal end of the long arm of the chromosome. These loci are arranged as CepB -(41%)- Ndh2 -(21%)- Est2 (Guerin et al. 1994). In the RFLP - maps mentioned above, two other isozyme loci, Adh10 locus for alcohol dehydrogenase and iBgl for beta- galactosidase are mapped respectively (Graner et al. 1993; Kleinhofs et al. 1993). Isozyme genes have been used for locating agronomically important major genes on chromosomes. Extreme earliness in 'Super Precoz' is conferred by the recessive allele ea\sp which is linked to Est1 with a recombination value of ca 2% (Gallagher et al. 1991). For disease resistance, the rust resistance gene Rph10 is on chromosome 3 and linked to Est2 with 15% linkage estimate (Feuerstein et al.1990). The resistance gene to Japanese strain II of barley yellow mosaic virus (BaYMV) is linked to the esterase complex with 7% and 10% in two cross combinations (Iida and Konishi 1994). The BaYMV resistance gene ym4 is closely linked to a RFLP marker (MWG10) with 1.2 cM, and MWG10 is located at 3.5 cM from Est1 (Graner and Bauer 1993). Furthermore, ym4 is linked to MWG010 and a primer OP.Z04 as ym4 -(0.9 cM)- MGW010 -(0.7 cM)- OP.Z04 (Ordon et al. 1995), and linked to the esterase complex with 3.4% and 8.3% (Le Gouis et al. 1995). The other BaYMW resistance gene tightly linked with the esterase complex (Konishi et al. 1989); Konishi and Kaiser 1991). It is noticeable that these BaYMV resistance genes are linked on the long arm of chromosome 3, and an allelism test and the orientation of these BaYMV resistance genes are required.

The recessive denso dwarfing gene has been one of the important and widely used in European barley breeding programmes. The denso dwarfing gene is located on the long arm of chromosome 3, approximately 8 cM distal to the RFLP locus Xspr170 (Laurie et al. 1993), and also linked to RFLP markers, WG110 and MWG803 (Thomas et al. 1995). On referring to several RFLP and classical maps, the denso dwarfing gene may be located on the central part of the long arm of chromosome 3.

References :

Feuerstein, U., Brown, A.H.D. and Burdon, J.J. (1990). Linkage of rust resistance genes from wild barley (Hordeum spontaneum) with isozyme markers. Plant Breeding 104:318-324.

Gallagher, L.W., Soliman, K.M. and Vivar, H. (1991). Interactions among loci conferring photoperiod insensitivity for heading time in spring barley. Crop Sci. 31:256-261.

Graner, A. and Bauer, E. (1993). RFLP mapping of the ym4 virus resistance gene in barley. Theor. Appl. Genet. 86:689-693.

Graner, A., Bauer, E., Kellermann, A., Kirchner, S., Muraya, J.K., Jahoor, A. and Wenzel, G. (1993). Progress of RFLP-map construction in winter barley. BGN 23:53-59.

Guerin, J.R., Lance, R.C.M., Brown, A.H.D. and Abbott, D.C. (1994). Mapping of malt endopeptidase, NADH diaphorase and esterase loci on barley chromosome 3L. Plant Breeding 112:279-284.

Iida, Y. and Konishi, T. (1994). Linkage analysis of a resistance gene to barley yellow mosaic virus strain II in two-rowed barley. Breeding Science 44:191-194.

Kleinhofs, K., Kilian, A. and Kudrna, D. (1993). The NABGMP Steptoe x Morex mapping progress report. BGN 23:79-83.

Konishi, T., Hayashi, J., Moriya, I. and Takahashi, R. (1984). Inheritance and linkage studies in barley. VII. Location of six new mutant genes on chromosome 3. Ber. Ohara Inst. landw. Biol., Okayama Univ. 18:251-264.

Konishi, T. and Kaiser, R. (1991). Genetic difference in barley yellow mosaic virus resistance between Mokusekko 3 and Misato Golden. Japan. J. Breed. 41:499-505.

Konishi, T., Kawada, N., Yoshida, H. and Sohtome, K. (1989). Linkage relationship between two loci for the Barley Yellow Mosaic resistance of Mokusekko 3 and esterase isozymes in barley (Hordeum vulgare L.). Japan. Breed. 39:423-430.

Konishi, T. and Matsuura, S. (1987). Linkage analysis of Est4 locus for esterase isozyme-4 in barley. BGN 17:68-70.

Laurie, D.A., Pratchett, N., Romero, C., Simpson, E. and Snape, J.W. (1993). Assignment of the denso dwarfing gene to the long arm of chromosome 3 (3H) of barley by use of RFLP markers. Plant Breeding 111:198-203.

Le Gouis, J., Erdogam, M., Friedt, W. and Ordon, F. (1995). Potential and limitation of isozymes for chromosomal localization of resistance genes against barley mild mosaic virus BaMMV). Euphytica 82:25-30.

Ordon, F., Bauer, E., Dehmer, K.J., Graner, A. and Friedt, W. (1995). Identification of a RAPD-marker linked to the BaMMV/BaYMV resistance gene ym4. BGN 24:123-126.

Singh, R.J. and Tsuchiya, T. (1982). Identification and designation of telocentric chromosomes in barley by means of Giemsa N-banding technique. Theor. Appl. Genet. 64:13-24.

Søgaard, B. and Wettstein-Knowles, P. von (1987). Barley: Genes and chromosomes. Carlsberg Res. Commun. 52:123-196.

Thomas, W.T.B., Powell, W., Waugh, R., Forster, B.P., Chalmers, K.J. Baurua, U.M., Swanston, J.S., Ellis, R.P., Jack, P. and Lea, V. (1995). Quantitative trait loci in a North West European spring barley cross-Blenheim x E224/3. BGN 24:41-45.