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PNL |
Volume 22 |
1990 |
RESEARCH REPORTS |
pages 62-63 |
IS THE LOCUS FOR THE GENE HET ON CHROMOSOME 7 or 5? A NEW LOOK AT LAMPRECHT'S LINKAGE GROUPS
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Swiecicki, W.K.
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Plant Breeding Station, Wiatrowo 62-100 Wagrowiec, Poland |
Previous results (2) analyzing the F2 generation of cross Wt11291 (het) x Wt11744 (tl r wsp) indicated linkage for mutant gene het on chromosome 7. More recent results from crosses between the type line for het and several testerlines are given in Tables 1 and 2. The results from cross Wt11291 (het) x Wt11238 (A d k wb s b cp te gp tl r) confirmed linkage between het and markers tl and r but the linkage was somewhat weaker than previously reported (2). In addition, linkage of het with markers gp, te and cp from chromosome 5 was found in the same cross (recombination values 21-28%). These results indicate that one gene is in two chromosomes according to the Lamprecht linkage map (1). It is possible that the heterophylus character is controlled by two genes but there is a low probability for the double recessive of one character to occur in mutant induction and the segregation for Het-het is fairly close to a 3:1 ratio (Table 1). Alternatively, all markers linked with het (from chromosomes 5 and 7) are in fact in one chromosome.
The latter explanation seems quite credible, even after 40 years of accepting Lamprecht's version of the map, and is in accord with the recent results of Weeden and Wolko (3) who suggest some major rearrangements to the previous Pisum gene map. For example, according to their results, the segment det curl r tl from chromosome 7 is linked with the gp teu lum-3 region of chromosome 5.
The present results fit the more recent map and indicate that het is on chromosome 5, probably between r and gp.
Table 1. Monohybrid segregation data for the F2 of cross Wt11291 (het) x Wt11238 (testerline)
|
Phenotype/Number |
Total |
Chi-square (3:1) |
|
|
Tl 298 |
tl 91 |
389 |
0.54 |
|
Cp 233 |
cp 62 |
295 |
2.50 |
|
R 251 |
r 65 |
316 |
3.31 |
|
Te 214 |
te 81 |
295 |
0.95 |
|
Gp 303 |
gp 72 |
375 |
6.73** |
|
Het 296 |
het 76 |
372 |
4.14* |
*,**Probability less than 0.05 and 0.01, respectively.
Table 2. Dihybrid F2 segregation data for het and several gene markers in the F2 of cross Wt11291 x Wt11238
|
Phenotype/Number |
Total |
Joint |
Rec. |
SE |
Phase |
|||
|
Tl Het 218 |
Tl het 68 |
tl Het 78 |
tl het 8 |
372 |
8.53** |
34.6 |
4.5 |
R |
|
R Het 190 |
R het 60 |
r Het 60 |
r het 4 |
314 |
9.89** |
29.1 |
5.1 |
R |
|
Cp Het 175 |
Cp het 57 |
cp Het 58 |
cp het 3 |
293 |
11.45*** |
25.9 |
5.4 |
R |
|
Te Het 156 |
Te het 57 |
te Het 77 |
te het 3 |
293 |
18.78*** |
21.7 |
5.5 |
R |
|
Gp Het 224 |
Gp het 71 |
gp Het 65 |
gp het 4 |
364 |
11.41*** |
28.1 |
4.8 |
R |
|
Tl Cp 188 |
Tl cp 40 |
tl Cp 45 |
tl cp 22 |
295 |
7.29** |
38.7 |
3.8 |
C |
|
Tl Te 174 |
Tl te 54 |
tl Te 40 |
tl te 27 |
295 |
7.18** |
39.4 |
3.8 |
C |
|
Tl Gp 248 |
Tl gp 42 |
tl Gp 55 |
tl gp 30 |
375 |
18.35*** |
34.4 |
3.1 |
C |
|
Cp R 186 |
Cp r 43 |
cp R 40 |
cp r 17 |
286 |
3.36 |
41.6 |
4.0 |
C |
|
Te R 172 |
Te r 38 |
te R 54 |
te r 22 |
286 |
3.96* |
41.6 |
4.0 |
C |
|
Gp R 211 |
Gp r 46 |
gp R 40 |
gp r 19 |
316 |
6.01* |
39.4 |
3.7 |
C |
|
Tl R 239 |
Tl r 6 |
tl R 12 |
tl r 59 |
316 |
219.14*** |
5.9 |
1.4 |
C |
*,**,*** Probability less than 0.05, 0.01 and 0.001, respectively.
Blixt, S. 1972. Agri Hort. Genet. 30:1-293.
Swiecicki, W.K. 1989. PNL 21:75-76.
Weeden, N.F. and B. Wolko. 1990. In Genetic Maps, Ed. S. O'Brien, Cold Spring Harbor, pp 6106-6112.