Locations of new mutations on 9S

--Oliver Nelson

This report covers investigations of the last few years on a group of mutants isolated by Gerry Neuffer and identified by him as being on 9S. I have reported on several of these mutants in mapping sessions at the Maize Meetings but not in the Newsletter. Data concerning some of these mutants have also been reported by the Missouri group.

There are two recessive virescent mutations in the distal part of 9S. These are v28 (formerly wlv-pg-585) and v31 (formerly gry-wlv-828). Both mutants are uncovered by the white deficiency (wd), and neither is allelic to yg2. Limited data from backcrosses, V sh bz wx/v Sh Bz Wx x V sh bz wx followed by selfing plants from different classes of kernels recombinant for the seed markers and then ascertaining the percentage of plants in each class segregating v/v plants gave estimates of 20% recombination between v28 and sh and 23% recombination between v31 and sh.

The dwarf mutation d*-660B proved to be an allele of d3 and should now be designated as d3-660B.

The mutant adherent-glossy-512B is not located on 9S since it showed no linkage to any marker on that arm.

The dominant Zebra stripe-8 (Zb8) mutation is located between bz and wx. Data from an F2 population (sh bz + Wx/Sh Bz Zb8 Wx) selfed showed 12% recombination between bz and Zb8.

The dominant mutation Cross-banded*-1456 (Cb) is also located between bz and wx. Data from a backcross progeny (Sh Bz Cb Wx/sh bz + wx) x sh bz + wx place Cb 3 map units distal to wx. A test of allelism of Zb8 and Cb has not yet been made. The phenotypes of plants heterozygous for these mutations are somewhat different. The Zb8/+ plants have a sharper transverse banding pattern on the leaves and are more vigorous than Cb/+ plants.

A third presumed dominant mutant, G6, was also received. I have not been able to identify G6/+ plants by their phenotype here in Madison in any of the four years in which I have grown progenies that should contain plants of this genotype. However, some plants in these progenies when selfed segregate for a bright yellow, lethal seedling that is apparently the homozygote. Since the heterozygote can be identified in Columbia, Missouri but not in Madison, Wisconsin, one should be cautious about attempting to use this mutation as a dominant marker. I have no data that locate this mutation on 9S.

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