Chromosome Translocations Induced in Triticum x Agropyron Hybrids by X Rays, Phosphorus 32 , and Sulfur 35

THE PRESENT STUDY was intended both to measure cytogenetic effects of various radiation treatments on certain members of the Gramineae and to produce agronomically useful derivatives, if possible. The cytological facets are recorded here, while the "practical" aspects-the attempted translocation of desirable Agropyron genes onto synapsing Triticum chromosomes-are being transcribed for publication elsewhere. A few relative papers may be mentioned. Ehrenberg et al. (1949) placed kernels of barley and 4x and 6x wheat in 5' ml. of P32 solution, at 0.02 to 25.0 yc/grain, for 3 davs. A dose of 5 ,uc was generally lethal and yielded cytogenetic disturbances comparable to those from 25,000 r of X rays. Arnason et al. (1948) placed dormant kernels of 6x wheat, one per test-tube, in 0.1 ml. of Knop's solution with either 0.18 1tc or 0.018 ,uc of p32, for 13 days. "Both concentrations were effective in causing chromosome breakage and rearrangements." This same group (Spinks et al., 1948) treated 6x wheat with p32 by sprouting the grains in water 48 hr. and then putting them (one per container) in test-tubes with either 0.18 or 1.8 Mc in 0.1 ml. of solution for 2 to 4 days. The higher dose was lethal; with 80 per cent uptake (measured), each seedling received ca. 1.4 tc. Similar tests with other genera showed that 1.8 yc Of p32 or Sr90 consistently killed or severely inhibited seedlings. Barley caryopses were soaked by Thompson et al. (1950) for 96 hr. in Petri dishes containing 0.625 to 10.0 Mc Of p32 and 0.1 ml. of water per grain. One pc of absorbed p32 was found to give the same average mutation rate as 19,500 r of X rays, and it was concluded: "Radiophosphorus is highly mutagenic . . . [and] is expected to become very useful in mutation work and plant breeding . . ." Shebeski and Lawrence (1954) administered P32 to caryopses, seedlings, and pre-meiotic plants of