URBANA, ILLINOIS
Maize Genetics Cooperation Stock Center

Additional linkage tests of waxy1 marked reciprocal translocations at the MGCSC

— Jackson, JD; Stinard, P; Zimmerman, S

In the collection of A-A translocation stocks maintained at MGCSC is a series of waxy1-linked translocations that are used for mapping unplaced mutants. Also, new wx1-linked translocations are being introduced into this series and are in a program to convert each translocation to the inbred backgrounds M14 and W23. These inbred conversions are then crossed together to produce vigorous hybrids that are homozygous for the translocation, in order to fill seed requests. Over the years, pedigree and classification problems arose during the propagation of these stocks. We have been able to sort through the problem ones, and can now supply good sources proven by linkage tests to include the correct translocated chromosomes. Additional pedigree information on bad sources is available should anyone want to check on sources previously supplied to them by the Stock Center.

Previously, we reported the linkage results for some of these stocks (MNL 72:81–82; MNL 73:88–89; MNL 74:67–69; MNL 75:68–71; MNL 76:65–67; MNL 77:79; MNL 78:65–66). Below is a summary of additional translocation stocks we have completed testing. Other translocation stocks will be tested as time allows.

We report here the results of two-point linkage tests for r1-wx1 T9-10b (Table 1) and three-point linkage tests for g1-r1-wx1 T9-10b (Table 2). The linkage tests were set up as modified backcrosses, as indicated in Tables 1 and 2. Ears for the two-point linkage tests were scored for the four classes. The non-waxy and waxy kernels from each ear were then planted in separate rows in a sand bench and the seedlings scored for golden vs. green phenotypes. The following linkage relationships were established: [wx1 T9-10b -13.9- g1 -16.1- r1] for the M14 source and [wx1T9-10b -15.1- g1 -14.8- r1] for the W23 source.

The Table 1 and Table 2 data are consistent with the order [T9-10b -16.3- g1 -8.9- r1] established by E. G. Anderson et al. (1954, MNL 28:13–16). However, our g1-r1 distances (16.1 and 14.8 cM) are greater. This may be due to an increase in number of progeny tested, from 135 (Anderson) to 2,000 and 4,000 (our data). Our g1-r1 data are consistent with the distance (14 cM) reported on the 1993 linkage map in Mutants of Maize, which apparently is based on the data of R. A. Emerson, G. W. Beadle and A.C. Frazier (1935, Linkage Group 10, pp. 66–70 in A Summary of Linkage Studies in Maize).

Table 1. wx1 T9-10b (2S.49; 9S.33)

A) The M14 source showed linkage of wx1 with r1.

2 point linkage data for r1-wx1 T9-10b
Testcross: [r1 wx1 T9-10b × R1 Wx1 N] × r1 wx1 N

source: 82-116-2^M14

% recombination r1-wx1=26.9 ± 1.0

B) The W23 source showed linkage of wx1 with r1.

2 point linkage data for r1-wx1 T9-10b
Testcross: [r1 wx1 T9-10b × R1 Wx1 N] × r1 wx1 N

source: 82-117-1^W23

% recombination r1-wx1=26.1 ± 0.6

Table 2. wx1 T9-10b (2S.49; 9S.33)

A) The M14 source showed linkage of wx1 with g1and r1.

3 point linkage data for g1-r1-wx1 T9-10b
Testcross: [G1 r1 wx1 T9-10b × g1 R1 Wx1 N] × g1 r1 wx1 N

source: 82-116-2^M14

% recombination wx1-g1 = 13.9 ± 0.8
% recombination g1-r1 = 16.1 ± 0.8
% recombination wx1-r1 = 29.9 ± 1.1

B) The W23 source showed linkage of wx1 with g1 and r1.

3 point linkage data for g1-r1-wx1 T9-10b
Testcross: [G1 r1 wx1 T9-10b × g1 R1 Wx1 N] × g1 r1 wx1 N

source: 82-117-1^W23

% recombination wx1-g1 = 15.1 ± 0.5
% recombination g1-r1 = 14.8 ± 0.5
% recombination wx1-r1 = 29.9 ± 0.7

wx1 T6-9a (6S.79; 9L.40)

The recessive wx1-marked sources for T6-9a that were checked showed no linkage with hcf26. Until new crossovers are recovered, wx18A T6-9(4778) (6S.80; 9L.30); wx1 can be used as a substitute.

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