| A new interspecific hybrid: Triticum aestivum
ssp. vulgare x Aegilops ventricosa Francoise DOSBA and Yvonne CAUDERON Station d'Amelioration des Plantes, 35-Rennes, and Station d'Amelioration des Plantes, 78-Versailles, France In order to transfer directly the genes of resistance to eyespot (Cercosporella herpotrichoides FRON.) of Aegilops ventricosa TAUSCH., 2n=28, to Triticum aestivum ssp. vulgare MAC KEY, 2n=42, an attempt was made to cross the two species. As far as is known, this is the first time that such a hybrid has been obtained (SIDDIQUI and JONES 1967, KNOBLOCH 1968). In 1970, crosses were made between two cultivars of the common wheat (Moisson, Top) and one semi-dwarf line (Mexique 50 x B 21) 2.6.10.3.6.4. as the female parent, and four different strains of Aegilops ventricosa as the male parent. Of the 920 florets of wheat pollinated by Ae. ventricosa, four seeds were produced only from the cross (T. aestivum cv. Moisson x Ae. ventricosa ssp. comosa Coss. and DUR.*). Two F1 hybrid plants were subsequently obtained. They grew quite normally and were intermediate to their parents for most morphological characters, although, in some cases, the traits of one parent were dominant (or epistatic) as recorded in Table 1. The hybrid plants were pollen sterile with non dehiscent anthers. The seed-setting was rather poor : only twelve seeds were obtained from fourty-two spikes, in a back-cross with Triticum aestivum and three seeds have been produced from one hundred and forty-five spikes from free pollination. Meiotic behaviour of the F1 hybrids was analysed only at the first metaphase stage and the mean pairing behaviour observed was compared to those of the parents, as shown in Table 2. Takinig into consideration the genome formulation of the parents established by KIHARA and others, the genomic constitution of the F1 hybrids might be A B D D MV, and the mean value of meiotic pairing about 7II D + 21I A B D MV. Considering the hypothesis proposed by KIHARA (1949) of a partial homology between the D and MV genomes some deviations, with the occurence of trivalents instead of bivalents, and less than twenty one univalents could be expected. In fact, as shown in Tables 2 and 3, in the material under investigation, a little less than two genomes (mean 5.03II, 1 to 7, mostly open)are able to associate as bivalents and might imply the common D genomes. Meanwhile the other chromosomes (univalents) might belong to the A B MV genomes. A comparison with the nearly asyndetic meiotic pairing reported by SIMONET (1952) in the F1 hybrids, with A B D MV genomes, involving Ae. ventricosa and some tetraploid wheat species, supports these results. |
| * Kindly supplied by Dr. H. KIHARA (his assession No. 1 coming from the Cornell University). |
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