Coordinator's report: Disease and pest resistance genes
J. Helms Jørgensen
Environmental Science and Technology Department, Plant Genetics,
Risø National Laboratory, DK-4000 Roskilde, Denmark

In BGN Vol. 22 compretensive lists were published on 1) Genes for powdery mildew reaction in barley in conjunction with a review (Jørgensen 1994) and 2) Loci for disease and pest reaction. These lists have been updated in BGN Vol. 23 and 24. Since that time the following new data have been published (to January 1996).

Two new powdery mildew resistance genes, Mla29 and Mla32, were described in H. spontaneum derived winter barley lines by Kintzios et al. (1995). Pickering et al. (1995) and Michel (1995) described a powdery mildew resistance gene, Mlhb, in barley (H. vulgare) transferred from H. bulbosum. This gene is located on chromosome 2 (2I). Xu and Kasha (1992) reported the transfer of a dominant gene (unnamed) for powdery mildew resistance from H. bulbosum to H. vulgare. In a study utilizing molecular marker analyses Maroof et al. (1994) found 27 loci, distributed on six of the barley chromosomes, that detected significant resistance effects to powdery mildew. Almost all chromosomal regions previously reported to carry genes for powdery mildew reaction were detected, plus the possible existance of one additional locus on chromosome 7. This falls in line with the finding (Backes et al. 1995) of one QTL on chromosome 7 H that explained 9% of the genetic variance for powdery mildew infection.

The same authors found 5 QTLs on four chromosomes affecting the trait infection by Rhynchosporium. One with the highest effect was on chromosome 1 H and three were on chromosomes 3 H, 6 H and 7 H, each with relatively smaller effects.

Borovkova et al. (1995) identified molecular markers linked to stem rust resistance gene rpg4 on barley chromosome 7 M. This gene is also described in a genetic stock in BGN 24, p. 169.

A single, dominant gene designated RphQ is thought to control the leaf rust resistance in barley accession Q 21861. This gene was found to be linked to a molecular marker, OU 022700 (Poulsen et al. 1995).

A gene Rh2 conferring resistance to scald (Rhynchosporium secalis) in variety 'Atlas' was found to be located on the distal part of chromosome arm 1S by linkage to a RFLP marker (Schweier et al. 1995).Scald resistance gene Rrs13 was located to barley chromosome 6 (6H) by linkage to four chromosome-6 molecular markers (Abbott et al. 1995).

Lastly, powdery mildew resistance genes are identified in about 700 mainly European barley varieties (Brown and Jørgensen, 1991). Recently, Boesen et al. (1996) preposed common European designations of barley and wheat resistance and virulence in Europe in order to facilitate the dissemination of data on powdery mildew resistances in commercial varieties of barley and wheat in Europe and on the corresponding virulences.

References:

Abbott, D.C., E.S. Lagudah and A.H.D. Brown, 1995: Identification of RFLPs flanking a scald resistance gene on barley chromosome 6. - Heredity 86(2): 152-153.

Backes, G., A. Graner, B. Foroughi-Wehr, G. Fischbeck, G. Wenzel and A. Jahoor, 1995: Localization of quantitative trait loci (QTL) for agronomic important characters by the use of a RFLP map in barley (Hordeum vulgare L.). - Theor Appl Genet 90: 294-302.

Borovkova, I.G., B.J. Steffenson, Y. Jin, J.B. Rasmussen, A. Kilian, A. Kleinhofs, B.G. Rossnagel and K.N. Kao, 1995: Identification of molecular markers linked to the stem rust resistance gene rpg4 in barley. - Phytopathology 85(2): 181-185.

Boesen, B., M.S. Hovmøller and J. Helms Jørgensen: Designation of barley and wheat powdery mildew resistance and virulence in Europe. - In: Proc. 3rd Workshop on Cereal

Mildews, Zürich, December 1995 (in press).

Brown J.K.M. and J. Helms Jørgensen, 1991: A catalogue of mildew resistance genes in European barley varieties. - In: Integrated Control of Cereal Mildews: Virulence Patterns and Their Change. (Ed J. Helms Jørgensen), Risø National Laboratory, Roskilde: 263-286.

Jørgensen, J. Helms, 1994: Genetics of powdery mildew resistance in barley. - Critical Reviews in Plant Sciences, 13(1): 97-119.

Kintzios, S., A. Jahoor and G. Fischbeck, 1995: Powdery-mildew-resistance genes Mla29 and Mla32 in H. spontaneum derived winter-barley lines. - Plant Breeding 114: 265-266.

Maroof, M.A. Saghai, Q. Zhang and R.M. Biyashev, 1994: Molecular marker analyses of powdery mildew resistance in barley. - Theor Appl Genet 88: 733-740.

Michel, M., 1995: Ûbertragung von H. bulbosum - Resistenzgenen gegenüber Mehltau und Gerstengelbmosaikvirus in die Kulturgerste. - Vortr. Pflanzenzüchtg. 31: 78-79.

Pickering, R.A., A.M. Hill, M. Michel and G.M. Timmerman-Vaughan, 1995: The transfer of a powdery mildew resistance gene from Hordeum bulbosum L. to barley (H. vulgare L.) chromosome 2 (2I). - Theor Appl Genet (in press)

Poulsen, D.M.E., R.J. Henry, R.P. Johnston, J.A.G. Irwin and R.G. Rees, 1995: The use of bulk segregant analysis to identify a RAPD marker linked to leaf rust resistance in barley. - Theor Appl Genet 91: 270-273.

Schweizer, G.F., M. Baumer, G. Daniel, H. Rugel and M.S. Röder, 1995: RFLP markers linked to scald (Rhynchosporium secalis) resistance gene Rh2 in barley. - Theor Appl Genet 90: 920-924.

Xu, J. and K.J. Kasha, 1992: Transfer of a dominant gene for powdery mildew resistance and DNA from Hordeum bulbosum into cultivated barley (H. vulgare). - Theor Appl Genet 84: 771-777.