In order to employ Lin's method (NL 46:193) to produce new B-A translocations, a recessive endosperm marker must be available on the arm on which translocations are desired. Until recently, no such markers were available on either arm of chromosome 8. When pro proved to be on chromosome 8 some distance proximal to v16, it seemed appropriate to use it to produce new B-A translocations, even though it might be on either arm. Accordingly, a hybrid stock segregating 2 recessive alleles at the pro locus was crossed by pollen from x-rayed plants of a colored hybrid with B chromosomes; exceptional kernels with the pro endosperm phenotype were saved. One plant grown from an exceptional kernel segregated pro when self-pollinated and when crossed onto a +/pro ear. Both pro and normal kernels from selfed and outcrossed ears segregated both normal and lethal pro seedlings, indicating frequent noncorrespondence of endosperm and endosperm genotype.
When heterozygotes of v21, which is distal to TB-8La on the long arm of chromosome 8, were crossed by 3 plants from the presumed new B-A translocation stock, 2 gave, respectively, 20 and 16 percent virescent seedlings in the progeny. Therefore, the presence of a new B-A translocation on the long arm of chromosome 8 has been established; it is hereby designated TB-8Lc. Because it is much nearer the centromere than TB-8La, it should replace TB-8La in the basic set of B-A translocations used to locate recessive genes to chromosome arm.
J. B. Beckett
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