A Database for Triticeae and Avena
For investigating geographical distribution of genotypes for the hybrid sterility, a total of 385 accessions of cultivated barley collected from different regions of the world and 26 accessions of Hordeum spontaneum were crossed with each of the tester stocks, Tayeh 1 (aa BB) and Mota 10 (AA bb). When the F/1/ hybrid between an accession and Tayeh 1 is fertile and the hybrid with Mota 10 is partially sterile, the accession examined is considered to possess the aa BB genotype. The reverse indicates that the accession carries the AA bb genotype. If both of the hybrids are completely fertile, the accession is thought to contain the AA BB genotype.
Table 1 shows a distinct difference between East Asian and Ethiopian accessions in genotypes for the hybrid sterility. Namely, about a half of the East Asian accessions examined possessed the aa BB genotype, while one-third of the Ethiopian accessions carried the AA bb genotype. The remains of both regions and all but one accessions of other regions were of the AA BB genotype. one exception of the AA bb genotype was found in Indian accessions. Meanwhile, all accessions of H. spontaneum possessed the same AA BB genotype.
From these results, it may be concluded that the prototype for the hybrid sterility is thought to be of the AA BB genotype, since H. spontaneum which is believed to be a progenitor of cultivated barley and most of the cultivated barley accessions possess the AA BB genotype. And, in the evolutionary process of barley, a recessive mutation at the sfg1 locus occurred in East Asia, while the other mutation at the sfg2 locus arose in Ethiopia independently. Furthermore, the fact that each of the mutant genotypes is distributed in the limited regions suggests both mutations occurred considerably later than the beginning of barley cultivation.
References
Fukushima, Y. and Konishi, T. 1994. Genetic studies on hybrid sterility in barley. Jpn. J. Genet. 69:719-726.
Konishi, T. and Linde-Laursen, I. 1988. Spontaneous chromosomal rearrangements in cultivated and wild barleys. Theor. Appl. Genet. 75:237-243.
Table 1. Geographical distribution of three genotypes for hybrid sterility in barley.
_______________________________________________________________ Region Number of accessions examined _______________________________________________ AA BB AA bb aa BB Total _______________________________________________________________ Japan 2O - 27 47 Korea 18 - - 11 China 20 - 16 36 South Asia 13 1 - 14 S.W. Asia 49 - - 49 Turkey 22 - - 22 Europe 11 - - 11 Ethiopia 120 57 - 177 _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ H. spontaneum 26 - - 26 _______________________________________________________________