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Wheat Information Service
Number 75: 1-6 (1992)


Review

A review on amphiploids in the Triticeae, obtained in Bulgaria during 1950-1990

P. Spetsov and M. Savov

Institute for Wheat and Sunflower, 9520, General Toshevo, Bulgaria


Twenty amphiploids in the tribe Triticeae, obtained in Bulgaria for a period of 40 years (1950-1990) have been summarized and listed here. They are arranged according to their chromosome number: four are tetraploids, eight- hexaploids, three-octoploids, one possesses 64 chromosomes, and four with 70 chromosomes. Almost all of them are synthetic forms that are induced by chromosome doubling of sterile interspecific or intergeneric hybrids.

Amphiploids provide a starting point for the production of alien additions, substitutions and interspecific transfers in wheat. Emphasis is made on their meiotic stability, seed setting, disease resistance and some other characters that are of importance for wheat breeding. Genome formulae and seed availability from developer are also presented.

The artificial doubling of chromosome numbers has been used as an efficient method for overcoming the sterility of intergeneric F1 plants. In Bulgaria, Doncho Kostoff initiated experiments to apply suitable techniques for doubling the chromosome number in sterile interspecific hybrids, especially for the cross Triticum timopheevi x T. monococcum. He named this amphiploid T. timococcum, showing resistance to fungal pathogens (after. Tsikov and Stoilov 1959).

After the intensive work of D. Kostoff on wide hybridization (Kostoff 1937, Kostoff and Arutiunova 1937, Kostoff 1940, 1941), many intergeneric hybrids and amphiploids were obtained by crossing cultivated wheats with alien species. In general, natural or synthetic amphiploids are easier to use for transferring desired alien genes to common wheat than are sterile hybrids from direct crosses between alien species and wheat.

The present review aims to group together and list all amphiploids obtained in Bulgaria during 1950-1990, and to briefly consider their important characters for wheat breeding. Origin, valuble features and seed availability of amphiploids are given in Table 1.

1. Amphiploids with 2n = 28

Aegilops squarrosa var. strangulata x T. boeoticum No.1
Savov and Panayotov (1989) describe two forms of the amphiploid with either T. boeoticum No.1 or No.3, both collected in Bulgaria. Plants having T. boeoticum No.1 as the parent are highly viable and more fertile than those with T. boeoticum No.3. The amphiploid is fully resistant to fungi irrespective of the aneuploid variation that is induced by the T. boeoticum form used in the cross.

The rachis and spikelets of the two F1 hybrids and amphiploids are non-fragile and free threshing. Breaking at different parts of the rachis is pronounced in the parents. This shows that strength of rachis and grain separation from the husks in Triticum species may be a result not only of munition but also of gene interaction.

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