GrainGenes

Mutations and Barley Breeding for Thermo-period Reaction and Cold Tolerance

V. M. Shevtsov, N. V. Serkin,  D. Chanda, and V.M. Chumak

Krasnodar  Lukyanenko Research Institute of Agriculture

KNIISH, Krasnodar, 350012, Russia, e-mail: vshevtsov@inbox.ru

 Barley is a very convenient biological object to induce  experimental mutations (Nilan et al., 1976; Lundqwist, 1986). It was shown that practically every trait can be changed with mutagen treatment (Rapoport, 1966; Gustafsson et al., 1971; Sigurbjornsson, 1983; Micke, 1989), including biological type and cold tolerance.  Three genes and their combinations control the biological type of barley plant: winter, spring, facultative. This mechanism can be modified  experimentally by the method of chemical mutagenesis. Results of our many years breeding activities with the use of induced mutations have confirmed this possibility. Usually, M²  of  winter barley populations were planted rather late in spring (March or early April) in order to select really spring or facultative mutants. The frequency of such type mutations was very low and varied from 0.05 to 1.3 %. In the group of spring barley mutants, induced on winter barley varieties, a six-rowed line 66 M4 and variety Plastoon are more promising. They originated from winter barley cultivar Cyclon and morphologically are very close to the initial form. In the wet environments they outyielded  two-rowed spring barley  checks by 10-20 %, but in dry conditions they are a bit less productive. Plastoon variety has performed very well especially in high yielding conditions due to stiff straw and good resistance to diseases.

In the group of facultative mutations the  unique genotype was identified. It became background for developing a mutant variety  Janus, which has performs as a rather cold tolerant winter barley after sowing in autumn and as a spring type after planting at any time in spring or summer without vernalization. Recently a new facultative variety Secret = Monolit x NEU 0.025 % - 12 hours has been released due to its increased cold tolerance and high yield. The original pant was selected from M2 after treatment of a pure winter barley variety Monolit with chemical mutagen nitroso-ethyl-urea 0.025%-12 hours. The new facultative variety headed after planting in March and early April. Variety Secret has higher cold tolerance than original winter form (table 1).

Among other winter cereals barley has comparatively low genetic variation in cold tolerance. Inter generic crosses of barley with winter rye and wheat were not successful so far. Therefore, the only way-out for breeders is to develop a new initial germplasm experimentally by means of mutations and recombinations. After artificial freezing in chambers about half million of M² plants annually with the selection pressure less than 1 % of survived seedlings, a series of unique macromutants has been isolated. Some of them have important agronomic characters. A mutant line 26M8 = (Pallidum 48 x nitroso-ethyl-urea 0.13 % - 6 hours) has deep tillering nodes (5-6 cm to 3 cm in released varieties).  Another macromutant MM-1 (Paoly x  nitroso-methyl-urea 0.02 % - 12 hours) possesses very high frost resistance. Our first released winter barley cultivar Debut=(Start x nitroso-methyl-urea 0.06 % - 12 hours) successfully combines winterhardiness, resistance to lodging and good yielding capacity. All of them were frequent parental partners in breeding programs to increase reliability and  yield stability of new cultivars. The involvement of drastic macromutants, carrying desirable traits, into hybridization has conditioned a real flash of transgressive variability, producing economically valuable genotypes. They include a released cultivar Radical=(Paoly x Mutant 52M1) x Novator. The new cultivar with good balance of economically important traits  played the  decisive role in a real break-through in barley grain production in the North Caucasus. While growing this cultivar, many farms have succeeded to harvest from 6 to 8 tons per hectare. Some years ago variety Radical was  changed by new released winter barley Bastion=Radical x Vavilon. It combines all advantages of both parental forms: cold tolerance, resistance to lodging, high yielding. The successful balance of economically important characters makes Bastion the most reliable for cultivation in the zones with frequent frosty winters. Recently, even more frost tolerant mutant has been identified. It was generated on facultative variety Secret after treatment with ethylene-imine 0.02%-6 hours. The mutant variety Taran has higher cold tolerance than initial and check varieties (table 2).

Thus, the method of experimental mutagenesis proved to be an useful breeding tool to induce a genetic variation in such  economically important characters as cold tolerance and thermo-and photo-period reaction. That resulted in developing released winter barley varieties tolerant to stressful factors  with reliable  winterhardiness and high yielding capacity.

References

Rapoport, I. A. 1966. Supermutagenes.  Science.  Moscow: 3-330.

Gustafsson, A., A. Hagberg , G.Persson and K.Wiklund. 1971. Induced mutations and barley improvement. Theoret. Appl. Genet., 41: 239-241.

Nilan, R., and A.Klenhots, and C. Sandler. 1976. Azide mutagenesis in barley. Third IBGS, Garching, 1975. Barley Genetics, 3: 113-122.

Sigurbjornsson, B. 1983. Induced mutations. In: Crop Breeding. Crop Science. Madison. USA.: 25-37.

Micke, A. 1989. 25 years Plant Breeding and Genetics Section of the Joint FAO/IAEA division. Mutation Breeding Newsletter, 34: 2-3.

Lundqvist, U. 1986. Barley mutants - diversity and genetics. In: Research and results in plant breeding. Svalof, 1886-1986: 85-88.