Status of an attempt to transfer the barley yellow dwarf virus resistance gene Yd2 of barley to hexaploid wheat
1984
McGuire, P.E. (California Univ., Davis (USA))
At the University of California work is underway to transfer the Yd2 gene of barley, which confers resistance to barley yellow dwarf virus (BYDV), to hexaploid wheat. The procedure being employed is the classical one, involving the production of an F1 plant between the donor and recipient species. A BYDV-susceptible wheat cultivar (Chinese Spring) was used as the seed parent and four barley cultivars possessing Yd2 gene were used to pollinate it. Successful embryos were cultured. The root tips of the plantlets (at the two-leaf stage) were excised for cytological analysis and the plantlets transferred to soil in pots. At the two-tiller stage the plants were treated with colchicine and when these plants flowered they were backcrossed with pollen of the wheat cultivar and the procedure was repeated. The results of two series of crosses show that 2 of 2, 1 of 1, 7 of 18, and 2 of 13 embryos of parent barley cultivars CI 3208-4, CI 2376, Atlas 68, and Cm 72, respectively, germinated and differentiated into plantlets. The range of variation in chromosome number was from 2n = 21 to 2n = 36. Of the 12 plants obtained, eight were haploids of Chinese Spring and only four possessed any barley chromosomes, and just two plants could provide a source of the Yd2 gene on barley chromosome 3. No fertile amphiploid was obtained. Plants with barley chromosome 3 will receive the most attention, and backcrossing will be continued
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