Map position of the Rms6 locus

  

Murfet, I.C. and                                                        School of Plant Science, University of Tasmania

                                                                                                             Hobart, Tas 7001, Australia

Rameau, C.                                                 Station de Genetique et d'Amelioration des Plantes, INRA

                                                                                      Route de St-Cyr, F78026 Versailles, France

 

       A recessive mutant with increased basal branching, S2-271, was obtained at Versailles by EMS treatment of cv Solara.  We found S2-271 was not allelic with ramosus mutants rms1 through rms5, which all show increased basal and aerial branching (1-3), but was allelic with mutant K586, which has a similar but weaker basal branching phenotype (2).  The new ramosus locus was symbolised rms6, with S2-271 as type line for allele rms6-1 and K586 as type line for allele rms6-2 (5).  In contrast to the situation in wild-type and rms1 through rms5 plants, buds in the cotyledonary axils of rms6 plants tend to be released from dormancy and may grow into secondary stems.

      To test for linkage with conventional markers, S2-271 was crossed with multiple marker line HL111.  Rms6 showed linkage in repulsion phase with group v markers r and tl.  A pure line, HL293, homozygous for bt, r, tl, gp, and rms6 was selected from cross S2-271 5 HL111 and crossed with wild-type lines Borek and Torsdag.  The coupling phase F2 data (Table 1) indicate Rms6 is in group v with a map sequence of:   Bt33R3Tl22Rms635Gp

  

Table 1. Combined F2 dihybrid segregation data for rms6 and pea linkage group V markers bt, r, tl and gp from crosses Torsdag (Bt R Tl Rms6 Gp) HL293 (bt r tl rms6 gp) and Borek (Bt R Tl Rms6 Gp) HL293; n = 128, 64 plants per cross.  All individual segregations are in accordance with a 3:1 ratio (P > 0.1).  D = dominant, R = recessive, first named locus shown first.  *P < 0.01, **P < 0.00001.

 

 

Phenotype

Joint seg.

Recomb.

 

Loci

 

DD

DR

RD

RR

Chi-sq.

fract.

SE

Rms6

Bt

65

23

28

12

0.21

47.3

6.4

Rms6

R

74

14

18

22

20.79**

26.6

4.7

Rms6

Tl

78

11

16

23

30.21**

22.1

4.3

Rms6

Gp

74

14

25

15

7.31*

34.6

5.4

R

Bt

74

18

19

17

9.96*

32.8

4.7

R

Tl

91

1

3

33

108.83**

2.7

1.5

R

Gp

73

19

26

10

0.75

44.6

6.2

Bt

Tl

75

18

19

16

9.06*

33.4

4.9

Bt

Gp

70

23

29

6

0.84

56.5

7.1

Tl

Gp

74

20

25

9

0.38

46.0

6.3

  

      Analysis of the F2 of cross S2-271 5 Torsdag using molecular markers confirmed that the Rms6 locus is in group v about 3 cM below marker R3_2000 (see 4) on the Gp side.  A molecular map and detailed report on the rms6 mutants will be given elsewhere (5).  We note the Rms5 locus is also in group v, but on the opposite side of Gp (1).

 

1.  Apisitwanich, S., Swiecicki, W.K. and Wolko, B.  1992.  Pisum Genetics 24: 14-15.

2.  Arumingtyas, E.L., Floyd, R.S., Gregory, M.J. and Murfet, I.C.  1992.  Pisum Genetics 24: 17-31.

3.  Blixt, S.  1976.  Agri Hort. Genet. 34: 83-87.

4.  Laucou, V., Haurogne, K., Ellis, N. and Rameau, C.  1998.  Theor. Appl. Genet. 97: 905-915.

5.  Rameau, C., Murfet, I.C., Laucou, V., Floyd, R., Morris, S. and Beveridge, C.A. (in preparation).