Disease Resistance of Triticum Timopheevi Transferred to Common Winter Wheat¹

Abstract

T RITICUM timopheevi Zhuk. is a species native to southern Russia and was introduced into this country by the U. S. Dept. of Agriculture in 1930. It is an unusual wheat because of its resistance to a number of diseases and because species crosses with it are highly sterile. It has proved highly resistant to leaf rust and stem rust under field conditions for the past 9 years at Madison, Wis. Several tests during this period indicate that it is resistant to bunt and mildew. It offers a new source of disease resistance which should be very valuable to the plant breeder if transferred to the common wheats. Rust resistance factors from other 14-chromosome wheats have been valuable in recently produced varieties of common wheat. Iumillo durum was the source of rust resistance in Thatcher and Y aroslav emmer for that in Hope which, in turn, has been used extensively in breeding new varieties. Investigations of Kihara and Lilienfeld 3 and of Kostoff 4 have shown that hybrids between T. timopheevi and other Triticum species are highly self-sterile regardless of chromosome number of the species used. From the cross T. vulgare Vill. variety Steinwedel X T. timopheevi, Pridham& obtained lines that were resistant to stem rust and leaf rust and T. vulgare in type.This paper briefly gives the history of a hybrid, its fertile progeny; and a few preliminary karyological observations. Crosses were made between Triticum timopheevi and a number of varieties of T. vulgare, the haploid chromosome numbers being 14 and 21, respectively. Difficulty was experienced in obtaining germinable hybrid seed when T. timopheevi was used as the female. The kernels developed to a normal size at the milk stage, but at maturity they were very shrivelled and most of them failed to germinate. There was no difficulty, however, in obtaining seed when T. vulgare was used as the female. The hybrid caryopses were smaller than normal for the female parent but were relatively plump with a visible and viable embryo. The first generation plants were highly self-sterile in all crosses. Thus, approximately 6,6oo selfed flowers from F 1 plants of all crosses have produced only 23 kernels, or 0.348% fertility. The anthers dehisced poorly and the iodine test showed about 95% of the pollen grains apparently sterile. Emasculating the F 1 plants and pollinating with T. vulgare

Tetraploid wheat species Triticum timopheevii and Triticum militinae in common wheat improvement

“…Due to genetic incompatibility and differences in genomic structures, the yield of hybrid grains in crosses of T. aestivum with T. timopheevii and T. militinae is extremely low (Shands, 1941;Allard and Shands, 1954;Skurygina, 1958;Leontjev, 1980;Kobylyanskyi and Fadeeva, 1986). For example, in efforts to transfer disease resistance from T. timopheevii to a cultivated wheat strain, Chopde and Deodikar (1964) pollinated over 2000 emasculated florets with the pollen of T. timopheevii, with a success rate of only about 5%.…”

“…Several successful transfers of resistance gene(s) from Triticum timopheevii to bread wheat have been reported (Pridham, 1939;Shands, 1941;Allard, 1949;Watson and Luig, 1958;Atkins, 1967;Peusha et al, 1995Peusha et al, , 1996. The inheritance of resistance to stem rust in adult plants (Allard and Shands, 1954) and resistance to physiological races of leaf rust and its inheritance have been described in selections derived from crosses of common wheat and T. timopheevii (Maan and McCracken, 1969).…”

The expression of components of seedling resistance to Erysiphe graminis f.sp. tritici in Triticum timopheevii and a hexaploid derivative

“…2« = 42). These pathogens include Puccinia species, and Erysiphe graminis DC (Shands. 1941;Mclntosh & Gyarfas.…”

Transfer of disease resistance genes from Triticum araraticum to common wheat

“…arcrrancuni w'nh !ie\aploid whcai without performing embryo rescue, btit mature ! "^ plants arc sterile (Shands 1941). Because of reduced recombination between '/'.…”