82 PNL Volume 19 1987 RESEARCH REPORTS
Adh-1, A MARKER LOCUS FOR RESISTANCE TO PEA ENATION MOSAIC VIRUS
Weeden, N. F. and R. Provvidenti NYS Agricultural Experiment Station,
Geneva, New York.
Resistance to pea enation mosaic virus (PEMV) is controlled by a
single dominant gene, En (2). The gene lies about 8 recombinant units
from tac on chromosome 3 (1). Several isozyme loci have been mapped to
this region of the chromosome, and on the basis of relative map distances
to various marker loci and clarity of phenotype, the locus Adh-1 appeared
to be the best candidate for an isozyme marker for En (3).
Adh-1 encodes the monomers of the more anodal alcohol dehydrogenase
isozyme in anaerobically treated seed or root tissue (4). A rare faster-
migrating ADH-1 allozyme has been identified in the cultivar Alaska and
line A683-168, both of which were obtained from G. A. Marx. These lines
were both homozygous for en. They were crossed with the PEMV-resistant
lines B880-221 and A76-46, respectively (also obtained from Dr. Marx).
Three populations derived from these crosses were analyzed for ADH-1
phenotype and for reaction to PEMV: an Alaska x B880-221 F2, an A79-46 x
A683-168 F2, and an F3 from the Alaska x B880-221 cross. The F3 consisted
of the progeny from 3 doubly heterozygous plants from the Alaska x B880-
221 F2.
The data for segregation at the two loci are presented in Table 1.
The F3 data shown represent the combined data for the three progenies, but
each progeny also showed normal segregation ratios at each locus. Table 2
presents the joint segregation analysis for the two loci. The 2-6% recom-
bination frequency is low enough to allow Adh-1 to be a very useful marker
for resistance to PEMV. As has been demonstrated previously (4), ADH-1
allozymes can be observed in seed tissue, permitting analysis of this
isozyme before germination, if desired. The allele coding for the fast
allozyme in Alaska and A683-168, because of its rarity in the cultivated
germplasm, should make an excellent marker for En. We are currently
developing homozygous lines that have this Adh-1 allele coupled with the
resistance gene.
1. Marx, G. A., N. F. Weeden and R. Provvidenti. 1985. PNL 17:57-60.
2. Schroeder, W. T. and D. W. Barton. 1958. Phytopathology 48:628-632.
3. Weeden, N. F., G. A. Marx, and E. Pagowska. 1985. PNL 17:75-76.
4. Weeden, N. F. and E. Pagowska. 1985. PNL 17:79-80.
PNL Volume 19 19 87 RESEARCH REPORTS
83
Table 1. Segregation at En, Adh-1, and Lap-1 in the F2 and F3 progeny
_examined._
No. Plants with designated Phenotype*
Expected
ratio
Goodness
of    fit (P)
Locus
fast/+
H
slow/-
Alaska x B880-221 (F2)
En
37
15
3:1
0.53
Adh-1

14
26
12
1:2:1
0.91
Lap-1
7
25
15
1:2:1
0.29
A76-46 x A683-168 (F2)
En
19
—
10
3:1
0.24
Adh-1
11
16
2
1:2:1
0.09
Lap-1
8
1*1
7
1:2: 1
0.95
Alaska x B880-221 (F3)
45
—
13
3:1
0.64
Adh-1
12
26
20
1:2:1
0.25
•Designations: dominant phenotype or homozygous fast = +; heterozygous = H;
recessive phenotype or homozygous slow = -.
Table 2. Joint segregation of En and Adh-1 .
Progenv
No. Plants with designated Phenotype*
Recomb.
Fraction
S.E.
+/+
+/H
+/-
-/+
-/H
-/-
Alaska x B880-221 (F2)
0
25
12
14
1
0
2
2
A76-46 x A683-160 (F2)
1
16
2
10
0
0
3
3
Alaska x B880-221 (F3)
1
24
20
11
2
0
6
3
•Designations as described in Table 1.
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