SINUATE LEAF sil LINKED WITH Wsp

PNL Volume 19 1987 RESEARCH REPORTS 33

Marx, G. A. NYS Agricultural Experiment Station

Geneva, NY 14456 USA

The current linkage map (1) places wsp in chromosome 7.
Authority for this position is Lamprecht, 1948 (2). I have at-
tempted in vain to verify this linkage on several occasions in the
past. Another attempt was made recently in light of the newly
found linkage between curl and r (3). Since curl apparently lay
on the opposite side of r from bt, there was a chance that curl
might show linkage with wsp.

Accordingly, a cross of the following constitution was made:
wsp Curl jit Sil x Wsp curl r bt sil. Because wsp, curl, and r
were the segregating mutants of primary interest, because wsp and
curl are excellent seedling markers, and because the R/- seeds
borne on the F1 plants could be separated from the r/r seeds
beforehand and planted separately as groups, the experiment was
conducted by planting the seeds in greenhouse flats, 63 seeds/
flat. Scoring of phenotypes was done when the plants were at the
seedling stage of development.

The female parent was Sil and the male was sil but this
difference did not appear to be germane at the time the cross was
made. However, since we routinely score populations for whatever
genes may be segregating, this population was scored for Sil-sil
in addition to Wsp-wsp, Curl-curl, and R-r. The position of sil
remains unknown. The Sil-sil difference was distinct and easy to
classify except in curl segregants, wherein sil could not be
confidently identified. Therefore, Sil-sil was scored only in
Curl/- segregants.

The results (Table 1), as in the past, provide no evidence of
linkage between wsp and chromosome 7 markers. They do, however,
confirm the linkage of curl and r reported previously (3). But
the cross provided an unanticipated bonus in showing that wsp and
sil are linked (Table 2). Having secured these rather persuasive
linkage data, I searched some of the data obtained in previous
years for supporting evidence of the wsp-si1 linkage. Such
evidence was found in an F2 population grown in 1976 (Table 3).
The 1976 data apparently were not reported because the population
contained a significant excess of wsp segregants, and this cast
some doubt on the validity of the data. In retrospect, however,
despite the significant departure of wsp from the expected se-
gregation, the data support the conclusion that wsp and sil are
linked. Unfortunately, the chromosomal location of the two genes
remains unknown, although there-is some inconclusive evidence sug-
gesting linkage between wlo and sil. (See also Weeden, this
issue, for additional information relating to the linkage of Wsp.)

1. Blixt, S. 1974. Hdbk. Genetics, Vol. 2, R. C. King, ed.
Plenum Press, New York. pp. 181-221.

2. Lamprecht, H. 1948. Agri Hort. Genet. 6:10-48.

3. Marx, G. A. 1986., PNL 18:45-48.

34 PNL Volume 19 1987 RESEARCH REPORTS

Table 1. Analysis of an F2 population involving Wsp, Curl, and R.


Wsp +	Curl	R +	No. 409	Gene pair	Chi-square	Re comb. fract.	S.E.
Wsp +	+	R +	No. 409	Gene pair	X Y Linkage	Re comb. fract.	S.E.
+	+		77
+	_	+	65	Wsp-Curl	0.50 3.37 0.10	-	-
+	-	-	72	Wsp-R	0.50 0.00 1.67	-	-
_	+	+	128	Wsp-R
-	+	-	23	Curl-R	3.37 0.00 122.70**	25.3	1.8
-	-	+	12 33 819		(Pop. C286-522-534)	•


Table 2. Linkage analysis of Wsp-Sil segregation in same F2 population in Table 1 but excluding curl segregants.
Wsp Sil	Wsp sil	wsp Sil	wsp sil	Total	Chi-square			Recomb. fract. 24.1	S.E. 3.7
352	138	133	7	630	X 2.59	Y 1.32	Linkage 27.94**	Recomb. fract. 24.1	S.E. 3.7
(Pop. C286-522-534)


Table 3. Joint segregation in F2 of Sil and Wsp.
Sil Wsp	Sil wsp sil Wsp sil wsp Tot.	Chi-square X Y Linkage	Recomb. fract.
1 86	53 92 6 337	3.0 10.09 12.40	30.1
(Pop. B276-473-497)

*****



	PNL Volume 19 1987 RESEARCH REPORTS 33

	SINUATE LEAF sil LINKED WITH Wsp Marx, G. A. NYS Agricultural Experiment Station Geneva, NY 14456 USA The current linkage map (1) places wsp in chromosome 7. Authority for this position is Lamprecht, 1948 (2). I have at- tempted in vain to verify this linkage on several occasions in the past. Another attempt was made recently in light of the newly found linkage between curl and r (3). Since curl apparently lay on the opposite side of r from bt, there was a chance that curl might show linkage with wsp. Accordingly, a cross of the following constitution was made: wsp Curl jit Sil x Wsp curl r bt sil. Because wsp, curl, and r were the segregating mutants of primary interest, because wsp and curl are excellent seedling markers, and because the R/- seeds borne on the F1 plants could be separated from the r/r seeds beforehand and planted separately as groups, the experiment was conducted by planting the seeds in greenhouse flats, 63 seeds/ flat. Scoring of phenotypes was done when the plants were at the seedling stage of development. The female parent was Sil and the male was sil but this difference did not appear to be germane at the time the cross was made. However, since we routinely score populations for whatever genes may be segregating, this population was scored for Sil-sil in addition to Wsp-wsp, Curl-curl, and R-r. The position of sil remains unknown. The Sil-sil difference was distinct and easy to classify except in curl segregants, wherein sil could not be confidently identified. Therefore, Sil-sil was scored only in Curl/- segregants. The results (Table 1), as in the past, provide no evidence of linkage between wsp and chromosome 7 markers. They do, however, confirm the linkage of curl and r reported previously (3). But the cross provided an unanticipated bonus in showing that wsp and sil are linked (Table 2). Having secured these rather persuasive linkage data, I searched some of the data obtained in previous years for supporting evidence of the wsp-si1 linkage. Such evidence was found in an F2 population grown in 1976 (Table 3). The 1976 data apparently were not reported because the population contained a significant excess of wsp segregants, and this cast some doubt on the validity of the data. In retrospect, however, despite the significant departure of wsp from the expected se- gregation, the data support the conclusion that wsp and sil are linked. Unfortunately, the chromosomal location of the two genes remains unknown, although there-is some inconclusive evidence sug- gesting linkage between wlo and sil. (See also Weeden, this issue, for additional information relating to the linkage of Wsp.)

	1. Blixt, S. 1974. Hdbk. Genetics, Vol. 2, R. C. King, ed. Plenum Press, New York. pp. 181-221. 2. Lamprecht, H. 1948. Agri Hort. Genet. 6:10-48. 3. Marx, G. A. 1986., PNL 18:45-48.