Significance of wheat-Aegilops crosses for the improvement of cultivated wheat

M. KASCHIRI

Institute fur Angewandtc Genetik (Vererbungs- und Zuchtungs-forschung) der Freien Universitat Berlin, Germany

Wheat-Aegilops crossings are of great importance to the studies of evolution as well as to the breedings of hybrids. Difficulties emerge in the production of amphidiploids from tetraploid wheat (AABB) and diploid Aegilops species, because of difficulties in crossing. Crossing experiments as well as cytogenetic analysis showed the following results:

1. The best results were shown with Aegilops longissima crossings.

2. The resulting triploids A_Em. B_Em. B_Sit. from AABB and B_Sit. B_Sit. showed in Meiosis a closer affinity between the B-genome from Ae. speltoides and the B-genome from AABB wheat. Ae. longissima and Ae. bicornis did not show such a close affinity.

3. The effectiveness of the 3 colchicine-methods (from SEARS, BELL, and SCHUMANN) were compared. The BELL- and SCHUMANN-methods were the best for obtaining hybrids.

4. The doubling of chromosomes in the triploid by colchicine treatment demostrated that the "Autoalloploids" forth the Aegilops longissima genome were more stable and fertile than those with the Aegilops speltoides genome

5. The author suggests the following terminology for the new "Amphidiploids"

a) T. dicoidspeltoides=(T. dicoccoides x Ae. speltoides) colch.
b) T. carthlispeltoides=(T. carthlicum x Ae. speltoides) colch.
c) T. dicospeltoides=(T. dicoccum x Ae. speltoides) colch.
d) T. dicoidlongissima=(T. dicoccoides x Ae. longissima) colch.
e) T. carthlilongissima=(T. carthlicum x Ae. longissima) colch.
f) T. dicolongissima = (T. dicoccum x Ae. longissima) colch.
g) T. durolongissima=(T. durum x Ae. longissima) colch.
h) T. timolongissima=(T. timopheevi x Ae. longissima) colch.
i) T. durosquarrosa=(T. durum x Ae. squarrosa) colch.
j) T. timosquarrosa=(T. timopheevi x Ae. squarrosa) colch.

6. The F₁-plants resulting from the crossings between A_Em. A_Em. -B_Em. B_Em. B_long. B_long. and AABB_timo. DD_squ. with Triticum aestivum (AABBDD) were sterile and suggest a new possibility for the breeding of hybrids, where as crossings between A_Em. A_Em. B_Em. B_Em. B_{Ae. spelt.} B_{Ae. spelt.} with wheat AABBDD generally resulted in a less positive fertility.

7. The R₁-plants show on the whole a resemblance to T. aestivum; the shape of the ear and the grain show substantially more characteristics from cultivated wheat and posses resistance to mildew and yellow rust. It may therefore be possible to use therse forms in the breeding of resistant varieties.

(Received March 29, 1974)