| New hybrids between Agropyron and wheat. I.
A. ciliare x wheat and A. smithii x wheat1 H.C. SHARMA and B.S. GILL Kansas state University Manhattan, KS 66506, U.S.A. Four Agropyron species, A. distichum (Thumb.) Beauv. (2n=4x=28), A. elongatum (Host) Beauv. (2n=2x=14 and 2n=10x=70), A. intermedium (Host) Beauv. (2n=6x=42, syn. A. trichophorum, A. glaucum, A. amurense) and A. junceum (L.) Beauv. (2n=2x=14 and 2n=4x=28) have been successfully crossed with wheat (PIENAAR et al., 1977; CAUDERON, 1979; ALONSO and KIMBER, 1980). All seven wheat - A. elongatum (2n=14) disomic addition lines and six wheat - A. intermedium disomic addition lines have been produced (CAUDERON et al., 1973; DVORAK, 1980). Several of these lines are resistant to leaf rust, stem rust and wheat-streak mosaic virus (WSMV). Disease resistant Agropyron genes have been transferred into wheat by induced homoeologous pairing and by X-ray irradiation (SEARS, 1977; KNOTT et al., 1977). One notable example is the Lr24 gene derived from A. elongatum (SMITH et al., 1968) present in several commercial winter wheat cultivars (BROWDER, 1980). It is obvious that Agropyron is a useful source of alien genetic variation in wheat. Several attempts to cross some other Agropyron species with wheat have failed, primarily because of early seed abortion. We successfully hybridized two additional species - A. smithii Rydb. (2n=4x=28) and A. ciliare Trin. (Fanch) (2n=4x=28) with wheat. Triticum aestivum L. cv. 'Chinese Spring' and winter cvs. 'Newton', 'TAM 105', 'Turkey' and 'Vona' were crossed in reciprocal combinations with A. smithii (TA2052) and A. ciliare (TA2006). In the cross T. aestivum (female) x A. smithii (male), 615 florets were pollinated and 5 seeds began to develop but aborted early. In the reciprocal combination, A. smithii x T. aestivum 268 florets were pollinated and 18 seeds began to develop. The embryos were cultured at day 12 on MURASHIGE and SKOOG (1962) medium supplemented with 0.4 mg/l thiamine-HCl, 10 mg/l each L-arginine HCl, glycine and L-tyrosine and containing 0.8% Bacto agar, and 2 hybrid plants A. smithii x 'Chinese Spring' and A. smithii x 'TAM 105' grew to maturity. The cross T. aestivum (female) x A. ciliare (male) was unsuccessful, but in the reciprocal combination one hybrid plant A. ciliare x 'Chinese Spring' was obtained by embryo culture from pollination of 350 florets. All three Agropyron - wheat hybrids were cytologically analyzed. The three hybrids were vigorous and tillered profusely. The spike and spikelet morphology was intermediate. A. smithii is rhizomatous and A. smithii x Wheat hybrids developed some rhizomes. The white scales on the stem in 'TAM 105' and in A. ciliare were also in the A. smithii x 'TAM 105' hybrid and in the A. ciliare x 'Chinese Spring' hybrid. The hybrids were totally sterile. |
| 1 Contribution No. 81-288-A, Department of Plant Pathology, Kansas Agricultural Experiment station, Manhattan 66506. We thank Dr. D.R. Dewey for Agropyron seeds. |
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