Geographical distribution of genotypes for hybrid sterility in barley
Geographical distribution of genotypes for hybrid sterility in barley
Takeo Konishi and Yoshihisa Fukushima
Faculty of Agriculture, Kyushu University, Fukuoka 812, Japan

Partially sterile F/1/ hybrids of barley were found when some Ethiopian accessions were crossed with Tayeh 1 (Chinese landrace), even though the parents were normally fertile (Konishi and Linde-Laursen 1988). The hybrids sterility is controlled by two duplicate genes (sfgl and sfg2, tentatively called a and b), and only female gametes carrying the both recessive genes are sterile, resulting in seed fertility of the F/1/ hybrids decreases to around 75% (Fukushima and Konishi 1994).

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.

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Region                 Number of accessions examined
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                AA BB         AA bb         aa BB         Total
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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
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