| On the ancestry of the Triticum vulgare varieties
Gabo and Timstein A. C. ZEVEN Institute of Plant Breeding, Wageningen, Holland WATSON and STEWART (1956) and KNOTT and ANDERSON (1956) concluded from the similarity in their reaction of stem and leaf rust resistance of the T. vulgare varieties Gabo and Timstein and the T. durum Gaza, that Timstein may be of the same parentage: (Bobin x Gaza) x Bobin (WATSON and WATERHOUSE, 1949). So Timstein would not derive from T. timopheevi x Steinwedel, as is suggested by PRIDHAM (1939). However, this conclusion appears to be premature because the investigations did not include Steinwedel. This should have been done as Steinwedel is one of the parents of Bobin (see Fig. 1). Obviously the only conclusion was that the breeder of Timstein was in the belief that he used a plant of T. timopheevi, but actually used a plant of T. durum. It would be of interest to check whether the genotypes for hybrid necrosis and hybrid dwarfness ("grass clump") could enable us to draw a more precise conclusion. HERMSEN (1963 a, 1966) investigated these two types of hybrid weakness and found that Bobin, Gabo and Timstein carry the same genes Ne1wne2d2D3 (see Table 1). HERMSEN (1963 b) showed that Bobin got its Ne1w-gene from Steinwedel. Furthermore, Steinwedel's genotype for dwarfness must be identical to that of Bobin because Thew carries the genes D2d3 (MCMILLAN, 1936). So Timstein could have derived its Ne1wne2d2D3- genes from Steinwedel. It is very likely that Bobin is the Ne1w-parent of Gabo as all the T. durum varieties and selections found to carry an Ne1-gene, carry the Ne1s-allele (HERMSEN, 1963 a; ZEVEN, 1965), also T. durum Gaza W 277 (ZEVEN, in press), which, originally coming from Giza, Egypt, was introduced into Australia and coded there Gaza W 277, and from there into USA as PI 189262. The genotype for hybrid necrosis of only one T. timopheevi-derivative, CI 12633 has so far been determined viz ne1ne2 (ZEVEN, in the press). The genotype for hybrid chlorosis is not of any help in solving this problem as almost all T. vulgare-varieties have the same genotype Ch1ch2 (HERMSEN, in the press) and as the Ch2-gene is located on chromosome 3D (TSUNEWAKI and KIHARA, 1961) it cannot be used to distinguish in T. vulgare-wheats, timopheevi-characters from durum-characters. Summarizing, the genotypes for hybrid necrosis, hybrid chlorosis and hybrid dwarfness of the varieties Bobin, CI 12633, Gabo, Steinwedel and Timstein cannot serve to identify the tetraploid parents of Timstein and so the conclusion of WATSON and STEWART, and KNOTT and ANDERSON that T. durum is one of the parents of Timstein might be correct. But it is certainly premature to say that Bobin in stead of Steinwedel is the T. vulgare-parent of this variety. |
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