3. Deficiencies


Crosses between translocations involving the same two chromosomes were studied for genetic and cytological evidence of intercalary deficiency or duplication. The crosses of T1‑7a x b and T4‑5c x T4‑5d had essentially normal pollen and ovules. The fomer when crossed with f produced about 11% of fine-striped plants in F1 indicating a viable deficiency for this locus. It was not transmitted through the pollen. In all the F1 plants of T1‑7a x b there was a short deficiency (indicated by a loop) in the long arm of 7 near the centromere. Although expected, there was no corresponding loop in chromosome 1.


The F1 of T3‑7a x b when crossed with floury‑2 gave some floury grains. This unlinked gene should be in the long arm of either 3 or 7.


Other crosses giving 25 to 35 per cent abortion in F1 were: T1‑9a x c, T2‑6b x T2‑6 (6049) and T5‑7a x c. In all of these F1's, there were 10 "bivalents" at diakinesis.


D. M. Gopinath (Bangalor 4, India)

and C.R. Burnham