The iojap gene reverts to normal

In certain backgrounds, especially in that of Tr inbred, ij ij plants are only slightly white-sectored but have very pale green ("light grainy") leaves and tassels. These pale green leaves occasionally have dark green, normal-appearing sectors, some as large as 1/8 to 1/4 of the leaf width. Green sectors could represent mutations of ij or other nuclear genes to normal, or changes in state or mutation of the chloroplasts. In one such plant in 1979, a green sector occurred in the tassel, encompassing 3 or 4 branches. Progeny from these branches were obtained as follows:
 
Female  Male Progeny
ij ij green branches 22 green, 21 iojap
ij ij iojap branches 3 green, 45 iojap
+ + green branches 4 +/+, 6 +/ij
+ + iojap branches 0 +/+, 8 +/ij

Progeny were identified as +/ij from F2 families, which segregated in a 3:1 ratio in each instance. The sector in the tassel was due to mutation from ij to +, and presumably reflects the same event occurring in the leaves.

E. H. Coe


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