Climatic Factors and Allele Distribution of Amy 1 and Amy 2 Loci in the Varieties of Spring Barley in the Territory of the Former Soviet Union

Abstract

The alpha-amylase isozymes in barley are controlled by the Amy 1 and Amy 2 loci located on chromosomes 6 and 1 (=6H and 7H), respectively. An analysis of spring barley varieties cultivated in the territory of the former Soviet Union until 1993 showed the distribution of 11 alleles at the Amy 1 locus and four alleles for another factor among these varieties—Amy 2. Their occurrence was not accidental. The most prevalent alleles were Amy 1.1 and Amy 2.1. The combination of these alleles in varieties was 44.6 ± 2.9%. The next most common were combinations of Amy 1.5 with Amy 2.1 at 10.9 ± 2.2% and Amy 1.4 with Amy 2.1 at 10.4 ± 2.1%. The allele distribution of the Amy 1 and Amy 2 loci in varieties zoned in 25 provinces of the Soviet Union, differing in climatic characteristics, was studied. It was found that the Amy 1.1 and Amy 1.3 alleles showed a positive relationship with hot temperatures, but negative with moisture. In contrast, the Amy 1.4, and Amy 1.6 alleles showed a negative response to heat, but positive to moisture availability. An analysis of the distribution reaction of alleles of another locus Amy 2 showed that the Amy 2.2 allele is associated with arid environmental conditions. Allele Amy 2.1, on the contrary, is confined to regions with good moisture supply and without extreme high temperatures. Continentality of climate did not play a significant role in the distribution of alleles of these loci. As a result, in the direction from north to south, the occurrence of the Amy 1.1 allele increased. Thus, in the northern latitudes of the European part, it was 27–31%, while in the southern steppe regions, the frequency of the Amy 1.1 allele increased to 78–85%. No such clear dynamics was traced in the direction from west to east. A similar pattern was found in the occurrence of the Amy 1.2 allele. With regard to the distribution of the Amy 2.1 allele in the direction from north to south, a tendency toward a decrease in the occurrence of this hereditary factor was observed. On the contrary, the frequency of another allele, Amy 2.2, in this direction among the zoned varieties of spring barley increased from 7–12 to 15–38%. Characteristically, the Amy 1.1 allele causes resistance to high temperature values and a lack of moisture, while the Amy 2.1 allele contributes to a positive response to good moisture availability in the absence of extreme high temperatures. The combination of these genetic factors determines its greatest distribution over the territory of spring barley cultivation.