01. Albinism in my pedigree 481 (formerly 472, and derived from Maize Cošp pedigree 44-74-1) is linked with "embryoless lethal" by about 1.5% crossing over. The Ňembryoless lethal" (or germless) in the inbred line is only partially lethal and quite variable; and it is difficult to identify all of the cases from superficial kernel structure. In 481 progenies the proportion of conspicuous embryoless varies considerably, always being less than the expected 1/4 and usually being about 1/5, 1/6 or even less. Pedigree 481-93 was an exception having approximately 1/4 con­spicuously embryoless kernels and making it possible to obtain data on the number of crossovers. Pedigree 481-93 was one among 235 plants self-pollinanted in pedigree 481.

 

481-93

259 seeds --> 204 normal + 55 conspicuously embryoless

259 seeds --> 197 greens + 2 albinos + 60 (did not germinate)

 

(Apparently 5 embryoless did not show, or there may have been some embryo-containing kernels which did not germinate.)

 

The 2 albinos were normal in stature, and were really crossovers in which genes for embryoless lethal and albino became separated to produce normal sized albinos.

 

481 albinos, generally, were very small and narrow leaved and evidently were the direct result of the linked embryoless lethal character. Some progenies gave the expected ratio of 3 normal green : 1 albino, in which the albinos were normal in structure. Other progenies gave ratios in the neighborhood of 5 or 6 normal green : 1 albino, in which the albinos were small narrow leaved and generally abnormal in structure. These latter progenies were the ones with embryoless showing as a kernel character and whenever the ones that do not germinate were added to the albinos the ratio of green to albinos was always brought to the 3:1 expectation. This would indicate that the ones which did not germinate (extreme embryoless) were genetically homozygous albinos. Examples are:

 

(a)

472-10 yellow seeds which were planted in field to produce 481.

 

240 green seedlings + 51 albinos (total 291) 4.7:1 (Total number of seeds sown was not determined.)

 

Out of a total of 291 seedlings there should have been 73 albinos.

 

 

 

 

(b)

481-13

 

 

 

Total seeds:

 

 

 

actual

439 yellow

+ 144 white

Total 583

 

expected

437 "

+ 146 "

 

 

 

 

 

 

Yellow seeds

328 green

+ 69 albinos

+ 42 did not germinate

 

White "

101 "

+ 21 "

+ 22 "

 

Total

429 "

+ 90 "

+ 64 "

 

There were 583 seeds. On this basis there should have been 437 green seedlings and 146 albinos. The 90 albinos actually obtained were far short of expectation but, if the number which did not germinate is added, the value is close to expectation. This batch of seeds was not sorted for embryoless.