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

Swiecicki, W.K.

 

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
chi-sq.

Rec.
frac.

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.

  1. Blixt, S. 1972. Agri Hort. Genet. 30:1-293.

  2. Swiecicki, W.K. 1989. PNL 21:75-76.

  3. Weeden, N.F. and B. Wolko. 1990. In Genetic Maps, Ed. S. O'Brien, Cold Spring Harbor, pp 6106-6112.