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United States Department of Agriculture

Agricultural Research Service

Staub: W6743, W6744, W6745
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Germplasm Release

Published in HortScience 31:1243-1245:1996

Cucumber germplasm: isozyme genetic stocks W6743, W6744, W6745

Additional index words. Cucumis sativus, allozyme, genetic markers, seed purity assessment, plant variety protection

Jack E. Staub1, Vladimir Meglic2 and Linda K. Crubaugh3

Vegetable Crops Research, U. S. Department of Agriculture, Agricultural Research Service, Department of Horticulture, University of Wisconsin, Madison, Wisconsin 53706

Received for publication______. Mention of a trade name, proprietary product, or specific equipment does not constitute a guarantee or warranty by the USDA and does not imply its approval to the exclusion of other products that may be suitable.

1 Research Horticulturist and Professor.
2 Former Graduate Student.
3 Research Technician.

A series of cucumber (Cucumis sativus L. var. sativus) populations (W6743, W6744, W6745) containing alternate alleles (allozymes) for 20 enzyme coding loci were released in September 1995 by the Agricultural Research Service, United States Department of Agriculture. Lines within each population have been created through backcrossing and self-pollination to incorporate allozymes in three genetic backgrounds; European glasshouse, U.S. processing (pickling) and U.S. market (slicing) types. Within each population inbreds developed from single plant selections should be heterogeneous at specific isozyme or morphological loci, and homozygous at others. These genetic stocks could be used for genetic marker research (e.g., linkage assessment, genetic drift detection) or by breeding programs (the incorporation of unique allelic constructs into elite lines) as a tool for varietal purity assessment and plant variety protection.


Allelic variation was initially observed in a survey of elite, publicly-released, processing cucumber inbred and plant introduction accessions present in the U.S. cucumber collection (USDA Regional Plant Introduction Station, Ames IA) in adenylate kinase (AK), fructose diphosphatase (FDP), glucosephosphate isomerase (GPI), glutathione reductase (GR), glycerate dehydrogenase (G2DH), isocitrate dehydrogenase (IDH), malate dehydrogenase (MDH), manosephosphate isomerase (MPI), peptidase with glycyl-leucine (PEP-GL), peptidase with leucyl-alanine (PEP-LA), peptidase with phenylalanyl-proline (PEP-PAP), peroxidase (PER), phosphoglucomutase (PGM), 6-phosphogluconate dehydrogenase (PGD), and shikimate dehydrogenase (SKDH) (Knerr et al., 1989, Knerr et al., 1994). Some allozymes of enzymes (e.g. G2DH, IDH, MPI, PGD, PEP-LA, SKDH) were not present in elite lines and were recovered from exotic germplasm (e.g., C. sativus var. hardwickii (R) Alef.; PI 183967 and PI 215589; Table 1). The inheritance of allozymes for these enzymes conforms to Mendelian expectations, and the linkage relationships among these allozymes and between allozymes and some economically important morphological loci have been characterized (Table 2; Knerr et al., 1989; Meglic, 1994).

Crosses were made among elite lines, and between elite lines and exotic germplasm to incorporate rare allozymes into adapted germplasm. Lines (>F4) were developed and used to determine the inheritance of the isozyme banding patterns resolvable in 15 enzyme systems using horizontal starch gel electrophoresis. These lines (5 to 10) were crossed to a European line (F3; European glasshouse type) derived from the intermating of three proprietary glasshouse lines from Numhems Zaden BV, De Ruiter Zonen BV, and Nickerson Zwaan, BV, Poinsett 76 (U.S. market type) and GY14 (U.S. processing type). These three lines were used as recurrent parents during backcrossing in which cross progeny heterozygous for isozyme loci were identified and used as parents. After four backcrosses, lines were self-pollinated for two generations and selected for alternate allozymes at each of 20 loci (Ak-2, Ak-3, Fdp-1, Fdp-2, Gpi-1, Gr-1, G2dh, Idh, Mdh- 1, Mdh-2, Mdh-3, Mpi-1, Mpi-2, Pep-gl, Pep-la, Pep- pap, Per, Pgm, Pgd-1 and Skdh), and uniformity in the three genetic backgrounds. This resulted in the production of 6 European glasshouse (W6743), 11 U.S. processing (W6744) and 8 U.S. market type (W6745) lines which were homozygous for alternate alleles [e.g. Ak- 2 (11) and (22)] at specific loci (Table 3).


Although these BC4S2 lines are distinct and can be placed into broad classifications according to potential horticultural utility, they are not phenotypically uniform within a specific type classification (Table 3). Lines within a specific type vary in skin texture (smooth or warty) and mature fruit color (green to orange) and length:diameter ratio (L/D; measured in mm), depending on genetic background. Lines derived using European germplasm as recurrent parents tend to be smooth-skinned, relatively long and fine-spined. Lines derived from backcrossing to U.S. processing and market lines vary in spine color (black or white) and some segregate for skin texture attributes (i.e., warts and spine thickness) and exhibit a range in L/D (2.0 to 4.8). This lack of uniformity could be due to pleiotropic effects and/or linkages between allozymes and morphological traits (Meglic, 1994).


Limited seed of individual lots of these genetic stocks and composite lots of 6743-5 are available upon written request to J. E. Staub, USDA, ARS, Department of Horticulture, University of Wisconsin, Madison, WI 53706.

Literature cited

  • Clayton, J. W. and D. N. Tretiak. 1972. Amine-citrate buffers for pH control in starch gel electrophoresis. J. Fish. Res. Board Can. 29:11-69-1172.
  • Knerr, L.D., J.E. Staub, Holder D.J., and B.P. May. 1989. Genetic diversity in Cucumis sativus L. assessed by variation at 18 allozyme coding loci. Theor. Appl. Genet. 78: 119-128.
  • Knerr, L.D.and J.E. Staub. 1992. Inheritance and linkage relationships of isozyme loci in cucumber (Cucumis sativus L.). Theor. Appl. Genet. 84:217-224.
  • Knerr, L.D., V. Meglic, and J. E. Staub. 1994. A fourth malate dehydrogenase (MDH) locus in cucumber. HortScience 30:118-119.
  • Market, C. L. and L. Faulhaber. 1965. Lactate dehydrogenase isozyme patterns of fish. J. Exp. Zool. 159:319-332.
  • Meglic, V. 1994. Inheritance and linkage relationship between biochemical and morphological loci in cucumber (Cucumis sativus L.). PhD thesis, University of Wisconsin- Madison, USA.
  • Richmond, R.C. 1972. Enzyme variability in the Drosophila williston group. 3. Amounts of variability in the superspecies D. paulistorum. Genetics 70:87-112.
  • Ridgway, G. L., S. W. Sherburne, and R. D. Lewis. 1970. Polymorphism in the esterase of Atlantic herring. Trans. Amer. Fish. Soc. 99:147-151.
  • Selander, R. K., M. H. Smith, S. Y. Yang, W. E. Johnson, and J. B. Gentry. 1971. Biochemical polymorphism and systematics in the genus Peromyseus. I. Variation in the old-field mouse (Peromyseus polionotus). In: Studies in genetics, Univ. of Texas Publication, Austin.

Table 1

Sources of the less common allozymes in 15 cucumber (Cucumis sativus L.) enzymesz.

192940Peoples Republic of China
Mdh-1 (2)171613Turkey
209064United States
Mdh-2 (1)174164Turkey
419214Hong Kong
Mdh-3 (2)255236Netherlands
432854People's Republic of China
Pep-gl(1)113334Peoples Republic of China

z Sources are only given for the less common allele of a locus used based on previous studies by Knerr et al. (1989) and Knerr and Staub (1992). There is also a common allele in addition to each of those listed above.
y Enzyme loci designation where multiple loci of an enzyme is distinguished by hyphenated numerals and alleles are enclosed in parentheses ( ).
x Heterogeneous population containing alternate homozygous and heterozygous genotypes.

Table 2

Enzymes assayed using specific buffer systems which provided adequate resolution of isozyme loci observed in cucumber (Cucumissativus L.).

No. ofx
Adenylate kinaseAK2.7.4.3S-42
Fructose diphosphataseFDP3.1.3.11A2
Glucosephosphate isomeraseGPI5.3.1.9R1
Glutathione reductaseGR1.6.4.2S-41
Glycerate dehydrogenaseG2DH1.1.1.29R1
Isocitrate dehydrogenaseIDH1.1.1.42S-41
Malate dehydrogenaseMDH1.1.1.37S-43
Manosephosphate isomeraseMPI5.3.1.8S-42
Peptidase with glycyl-leucinePEP-GL3.4.13.11A2
Peptidase with leucyl-alaninePEP-LA3.4.13.11M1
Peptidase with phenylalanyl-prolinePEP-PAP3.4.13.11S-41
6-phosphogluconate dehydrogenasePGD1.1.1.43S-42
Shikimate dehydrogenaseSKDH1.1.1.25S-41

z Enzyme commission number.
y Buffers of Clayton and Tretiak (1972), Ridgway et al. (1970), and Selander et al. (1971), Markert and Faulhaber (1965) designated as C, R, and S or M, respectively.
x Loci designated by previous examination (Knerr and Staub, 1992) or during this survey using standard criteria and nomenclature (Richmond, 1972).

Table 3

Allozyme and morphological variation in genetic stocks of cucumber (Cucumissativus L.).

 Allelic constitution of enzyme coding locizFruit Characteristics y
European greenhouse type
6743A1222222222112212222211121122222211122222SegG-Y to Y-GW3.8-6.0
6743B1222222222112212122211121112222211122222SegG-Y to Y-GW3.8-6.0
6743D1212121122112222112211121211122211111222SmG-Y to YW4.0-5.5
6743E2222222222221122112211221122222211112222SmG-Y to YW3.8-5.6
6743I2222222222222222112211111112222211112211SmG to YW5.8-6.0
U.S. processing type
6744C1212221122112212112211222212222222122222WG to OW2.8-3.0
6744F2212121122112222222211222222222211112222WG-Y to YW3.2-4.0
6744G2212112211112222122212222222122211112212WY to Y-GW3.0-4.5
6744H2212121122112222122222222222222211112211WY to Y-GW2.8-3.5
6744I1122222212112222112222222212221111112222WY to Y-GW2.5-3.3
6744L1122221111112222112222222211221111112222SegY-G to YW2.3-2.6
6744M1122221122112222111111221111221111112211SegG-Y to YW2.2-3.2
6744P1211111122112222112211112211221111111122WY-G to YW2.7-3.5
6744T1112121122112222112211121111221111111222SegO to YGB2.0-3.5
U.S. market type
6745A2222112222111222122212111211222211122222SegO-Y to YSeg3.5-4.3
6745D2222122222122222112211111112222211112212SegO-Y to YSeg3.8-4.3
6745E1222122222112222111122121111222211121222SegG-Y to YW3.3-3.8
6745F1122112222112222112212111111222211121122SegG to YW3.0-3.8
6745G1122112222112222112222111111222211111122SegY-G to YW3.8-4.5
6745H1222122222112222111212121111222211121222WY-G to YW3.8-4.8
6745K1112111122112211112212112211222211222211SegO to YB3.0-4.3

z Allozymes that occur in highest frequency are given the mobility designation 100. All other alleles produce protein products with relative mobilities to allozyme 100 (mm) as follows:
Ak-2(1)-98, Ak-3(1)-98, Fdp-1(1)-96, Gpi-1(1)-98, Gr-1(1)-97, G2dh(1)-94, Idh(1)-94, Mdh-1(2)-101.5, Mdh-2(1)-98, Mdh-4(2)-102, Mpi-1(1)-96, Mp-2(2)-103, Pep-gl(1)-98, Pep-la(1)-98, Pep-pap(1)-95, Per(2)-105, Pgm(2)-102.5, Pgd-1(1)-98, Skdh(1)-98.
ySkin texture: Sm = smooth, W = warty, Seg = segregating; Skin color: G = green, Y = yellow, O = orange; Spine color: W = white, B = black, Seg = segregating;
xL:D = length:diameter ratio.

Last Modified: 8/13/2016
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