SUPPLEMENTAL MAPPING DATA FOR CHROMOSOME 6

34 PNL Volume 20 1988 RESEARCH REPORTS

Skarzynska, Aldona Garden Plant Breeding Station, Zielonki, Poland

The gene for resistance to Pea Seedborne Mosaic Virus (PSbMV) in pea has been found in two accessions, PI 193586 and PI 193835 (2). Using these lines as sources of resistance, Hagedorn and Gritton developed hor-ticulturally improved lines designated Wisconsin 7105 and Wisconsin 7106, both resistant to SbMV.

Gritton and Hagedorn (1) then reported the linkage of the gene sbm with wlo in chromosome 6 with recombination fraction of ca. 12%. The linkage was confirmed by Hampton and Marx (3) with the suggestion of using wlo as the marker gene in selection for resistance.

We tested this suggestion in our own breeding work. Two sbm lines, Wis 7105 and Wis 7106, were crossed with wlo lines Wt 11340 and 10341 (from the Wiatrowo pea genebank), a repulsion phase cross. The dihybrid segregation in F2 gave little evidence of linkage:


Wlo Sbm	Wlo sbm	wlo Sbm	wlo sbm	Total
233	146	90	41	510

Although those data do not show linkage between sbm and wlo there was an excess of segregants scored as resistant, so there was a possibility that susceptible plants had been misclassified as resistant. Further studies on the localization of sbm therefore were pursued; these studies included other known Loci oi chromosome 6.

In the first step Wt 11778 = PI 193586 (sbm) was crossed with Wt 16140 (wlo art-1 ) . All F1 plants proved susceptible to PSbMV. Monohybrid segregation with no disturbances was observed in F2 (Table 1A). In a population of 906 plants, the dihybrid segregation for sbm-wlo showed deviations from independence and a CrO value = 23.0 (Table IB); for sbm-art-l the calculated CrO value was 41.2.

Wt 12070 == Wis 7106 (sbm) was also crossed with Wt 16141 (art-1 p). Again the F1 plants were susceptible and an undisturbed monohybrid segregation was observed (Table 2A). The dihybrid segregation (about 800 plants) showed a linkage between Sbm and Art-1 with a CrO value of 34.2 +/- 3.1% and between Sbm and P with CrO value of 24.5 +/- 13.3% (Table 2B).

Thus none of the above genes (wlo, art-1, or p) seems to be a closely Linked marker for sbm. On the basis of the gene order presented by Marx (4) and on our own results described above the following situation is proposed :

PNL Volume 20

1988 RESEARCH REPORTS

Table 1. Phenotypic distribution in an F₂ population segregating for genes on chromosome 6 from Wt 11778 (sbm) x Wt 16140 (wlo, art-1) .

A. Monohybrid F₂ segregation.


Wlo 672	wlo 238	Total 910	Chi-square (3:1)
Wlo 672	wlo 238	Total 910	0.65
Sbm 690	sbm 216	906	0.65
Art-1 701	art-1 208	909	2.17


B. Joint segregation of sbm with wlo and art-1.
B. Joint segregation of sbm with wlo and art-1.					Joint Chi- square	Phase	R.F.	S.E.
Wlo Sbm 464	Wlo sbm 204	wlo Sbm 226	wlo sbm 12	Total	Joint Chi- square	Phase	R.F.	S.E.
Wlo Sbm 464	Wlo sbm 204	wlo Sbm 226	wlo sbm 12	906	63.42	R	23.0	3.1
Wlo Art-1 568	Wlo art-1 102	wlo Art-1 132	wlo art-1 106	908	83.53	C	30.5	1.9
Sbm Art-1 516	Sbm art-1 174	sbm Art-1 183	sbm art-1 33	906	8.86	R	41 .2	2.7

Table 2. Phenotypic distribution in an F₂ population segregating for genes of chromosome 6 from Wt 12070 (sbm) x Wt 16141 (art-1, p).


A. Monohybrid F_? segregation.
Sbm 614	sbm 186	Total	Chi-square (3:1)
Sbm 614	sbm 186	800	1.31
Art-1 620	art-1 181	801	2.47
P 611	P 187	798	1.04


B. Joint segregation of sbm with art-1 and p.					Joint Chi- square	Phase	R.F.	S.E.
Sbm Art-1 452	Sbm art-1 162	sbm Art-1 167	sbm art-1 19	Total	Joint Chi- square	Phase	R.F.	S.E.
Sbm Art-1 452	Sbm art-1 162	sbm Art-1 167	sbm art-1 19	800	21.19	R	34.2	3.1
Sbm P 435	Sbm p 177	sbm P 176	sbm p 10	798	44.96	R	24.5	3.3
Art-1 P 536	Art-1 p 82	art-1 P 75	art-1 p 105	798	159.02	C	23.1	1.7

36 PNL Volume 20 1988 RESEARCH REPORTS

It appears from these data that sbm is located in the Pl end of chromosome 6.

1. Gritton, E. T. and D. J. Hagedorn. 1975. Crop Sci. 15:447-448.

2. Hagedorn, D. J. and E. T. Gritton. 1971. PNL 3:16.

3. Hampton, R. 0. and G. A. Marx. 1981. PNL 13:16.

4. Marx, G. A. 1982. PNL 14:50-52.

I acknowledge the cooperation of Dr. W. K. Swiecicki and K. Leraczyk, M.Sc, for pea lines from the Wiatrowo genebank and for computer facilities to calculate estimates.

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