A new B-A translocation on 5L, designated TB-5Ld, has been produced by crossing a pr stock with pollen X-rayed before the second pollen division (Lin, B.-Y., NL 46:193). The translocation uncovers (i.e., is proximal to) bv1, ae1, pr1, lw2, and gl8. The genes bt1 and td1 are not uncovered, and the position of v3 with respect to the translocation is uncertain because the phenotype is poorly expressed.
Although further testing with na2 and v3 is needed, the breakpoints of TB-5La, -5Lb, and -5Ld appear to be nearly the same, as all uncover or fail to uncover the same genes. Because bt1 and bu1 are mapped only 5 units apart, the region may be particularly susceptible to breakage by X-rays or perhaps may be quite long with little crossing over.
J. B. Beckett
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