Pisum Genetics           Volume 27      1995                Research Reports          page 21

Mapping of nod-4, a new hypernodulating mutant in pea*

Sidorova, K. K. and Uzhintseva, L. P.                                Institute of Cytology and Genetics

                                                                                                     Novosibirsk 630090, Russia

Recently we have described a new hypernodulating mutant in pea, obtained after the treatment of seeds of cv. 'Ramonsky 77' with N-nitroso-N-ethylurea (3). The mutant line K301 is characterized by excessive nodule number (more than 1000 per plant), by high nitrogenase activity even in the presence of nitrate, and by a different (fasciated) stem morphology. The phenotype is inherited as a recessive. The gene symbol nod-4 is proposed (3).

The location of nod-4 on the pea genetic map was investigated by conventional segregation analysis of several crosses involving tester lines WL1238, WL1132 and WL741 from the Nordic Gene Bank (4). Linkage was found between nod-4 and two morphological markers gp (yellow pod) and cp (curved pod), suggesting that nod-4 is located on linkage group V. The data are given in Table 1.

Table 1. Results of joint segregation analysis for genes nod-4, cp and gp.

Cross

Gene pair

Phase

Phenotype

Joint
seg. c2

Recomb.
freq. ± SE

AB

Ab

aB

ab

K301xWL1238

nod-4-gp

R

173

92

81

3

31.2

18.0 ± 5.1

 

nod-4 -cp

R

188

77

82

2

25.9

16.6 ± 5.2

 

gp-cp

C

244

11

26

68

181.5

10.4 ± 1.7

K301xWL1132

nod-4 - gp

R

161

88

62

5

19.8

25.0 ± 5.2

K301xWL741

nod-4 - gp

R

103

53

51

5

13.0

27.9 ± 6.2

 

The mapping data indicate that nod-4 is distinct from nod-3, a previously described gene conditioning hypernodulation, which has been localized near D on linkage group IB (2, 5). The interactions between these two hypernodulating mutants (nod-3, nod-4), as well as with four other mutants (190F, 191F, P77, P79) with excessive nodule number described by Duc et al. (1), remain to be investigated.

1.           Duc, G. and Messager, A. 1989. Plant Sci. 60:207-213.

2.           Jacobsen, E. and Feenstra, W.J. 1984. Plant Sci. Lett 33:337-344.

3.           Sidorova, K.K. and Uzhintseva, L.P. 1992. Soviet Genet. 28:494-500.

4.           Sidorova, K.K. and Uzhintseva, L.P. 1994. Proc. Russian Acad. Sci. 336:847-849.

5.           Temnykh, S.V., Kneen, B.E., Weeden, N.F. and LaRue, T.A. 1995. J. Hered.
86:303-305.

*Synopsis of work previously published (3, 4) in the Russian language.