1. Pink aleurone color.
A pink aleurone color, phenotypically resembling that described by Ruth Sager in Maize News Letter No. 22, has been observed in stocks of corn homozygous a1 C R pr in y. Data covering two generations do not indicate maternal inheritance, however, as reported by the Columbia worker.
Attention was first drawn to the presence of this pink aleurone in stocks segregating for an undetermined germless condition. On selfed ears homozygous a1 C R pr in y and segregating Gm gm, a ratio of 3 white to 1 pink aleurone was noted. All of the pink kernels were germless. Upon close examination, however, some of the non‑germless kernels were found to be slightly mottled with pink. Others showed no pigmentation. Selfed plants from non‑germless pigmented kernels produced ears resembling the ears from which they came. Non‑germless colorless kernels produced ears in which all of the kernels were colorless if germless was not segregating. If germless was segregating, the germless kernels were very slightly pigmented.
When this a1 C R pr in y Gm/gm stock was crossed with a related homozygous A C R pr in y Gm line, the kernels were all intense red as expected; but upon selfing a new phenotype, "rust" aleurone, appeared in the ratio 9 intense red : 3 rust : 4 white on half of the ears harvested in 1948. The other half segregated the expected 3 intense red : 1 white, and some of the near‑colorless kernels showed the pink aleurone color exhibited by the one parent stock. Likewise on the ears segregating rust, some of the kernels were very slightly mottled pink even though germless was not segregating on any of these ears. It is not possible at this time to conclude that the pink aleurone color, observed in the presence of recessive a1, is related to the rust aleurone color produced apparently in the presence of A1 even though both conditions appeared in the same stock.
The germless condition must be a strong modifier of the pink aleurone color, since on non‑germless kernels a few clumps of aleurone cells on the crown of the kernels may be pigmented to give a very faint mottled appearance, whereas on germless kernels the pigment is rather evenly dibtributed and more intensely developed. Gerrlcss and pink aleurone are separable. F2 data indicate that they are not linked.
There is likewise some indication that in may modify the pink aleurone color - and possibly the rust color. Since most of the stocks involved in this work have been in in, this gene may have been a factor in the original detection of these aleurone phenotypes.
Data from the F2 of the mating homozygous a1 C R pr in y (carrying pink aleurone) x homozygous A R Pr In y (c sh wx), where the rust phenotype also appeared, indicate that (1) the rust type may be modified in the presence of these several segregating genes to various shades of brown and (2) the expression of rust depends upon a gene linked with c sh wx. Whether this gene is bz has not been determined.
Robert I. Brawn