ANNUAL  REPORT
Calendar Year 1997

1.  PROJECT: NRSP-6: INTER-REGIONAL POTATO INTRODUCTION PROJECT

Introduction, Preservation, Classification, Distribution and Evaluation of  Solanum Species.

2.  COOPERATIVE AGENCIES AND PRINCIPAL LEADERS

United States Department of Agriculture

Administrative Advisors

3.  PROGRESS AND PRINCIPAL ACCOMPLISHMENTS

A.  Introduction of New Stocks

Dr. Spooner, in collaboration with Drs. Antonio Rivera-Pena (Mexico), Ronald G. van den Berg (The Netherlands), and Konrad Schuler (Germany) participated in a successful  expedition to collect wild species of potato in Mexico from August 21st to October 31st. This collection trip procured 95 new accessions of 24 different Solanum species.

Dr. Bamberg collected five accessions in two expeditions to the southwestern-region of the United States and had five accessions sent to NRSP-6 by cooperators from that region.

A total of 158 accessions were brought through Quarantine in 1997, assigned PI’s, and are now available from the NRSP-6 Solanum germplasm collection, 110 accessions as true seed and 48 as in vitro clones.

In 1997, 183 accessions were planted out in the spring quarantined increase. Of the 183 accessions, 119 germinated and were grown out. One hundred fourteen of these were released and added into the collection (five were virus suspect and not released).  Of the 114, 12 were CCC donations from Columbia, one was a Lopez collection from Columbia, 94 were from Spooner’s 1993 Bolivia collection, and seven were collected in Mexico by Hjerting.  Four of the accessions released from quarantine were assigned PI’s in 1996, thus the discrepancy between number of accessions released and number of accessions assigned PI’s.

An additional 48 clones were added to the in vitro collection in 1996 as foreign varieties or genetic stocks, including 19 R-free late blight resistant clones from CIP.

B.  Preservation and Increase of  Stocks

In 1997, 238 accessions were increased. From US Quarantine 183 accessions were received for a joint seed increase and quarantine virus testing at NRSP-6.   Of the 183 accessions, 64 failed to germinate, five were virus suspect and not released, and 114 are being incorporated into the NRSP-6 inventory.

This year a total of 700 potato spindle tuber viroid (PSTV) tests were performed on seed increases, seed lots and research materials. Germination tests were performed on 972 accessions, and ploidy determinations were done on 91 accessions.

C.  Classification

Dr. Spooner continues to resolve problems in taxonomic classification which impede efficient documentation and use of the germplasm. This year an extensive study of the S. canasense complex of species was continued.  Molecular analysis of relationships of S. astleyi and S. boliviense were completed.  Insights gained from this study will allow accessions to be assigned stable species’ names based on empirical differences.

D.  Distribution

NRSP-6 distributed 7,204 units of seed (50 seeds per unit), 40 tuber families and 1,146 in vitro stocks to clientele in 23 states of the United States and 16 other countries.  Internally, NRSP-6 used 6,883 units of seed for chromosome counts, germination tests, identification and taxonomic check plantings, in-vitro maintenance, seed increases, PSTV tests, and miscellaneous plantings.  The volume and types of stocks sent to various consignee categories are summarized in the table below.

VOLUME AND TYPES OF STOCKS DISTRIBUTED

¹ Types of stocks sent/(number of seeds, tubers or plantlets per standard shipping unit):
    S= True Seeds/(50), TF= Tuber Families/(10),  IVS=in vitro stocks/(1).

²  Includes chromosome counts, germination tests, ID and Taxonomic check plantings, in
    vitro maintenance, seed increases, PSTV tests, and miscellaneous plantings and NSSL
    seed backup.

E.  Evaluation of Stocks

Mission

The project's mission with respect to evaluation is to locate and characterize useful traits so that the best materials and most efficient approaches are available for subsequent germplasm enhancement.

1. Special Quarantine Seed Increases

This cooperative project with the US Quarantine Lab, by which quarantine testing and seed increases are done concurrently at NRSP-6, has greatly reduced time and effort required to import valuable germplasm.  This year we successfully processed germplasm from Dr. Spooner's collecting expeditions to Bolivia.

2. Late Blight Screening

New forms of the late blight pathogen have developed into a severe threat to the US potato crop.  In 1997 we continued three cooperative projects:

      1)  BC, Canada with Dr. Ken Ng: This project facilitated fine
           screening of non-Mexican species diploids of Series Tuberosa
           segregating for extreme resistance.

      2)  Cornell, New York: Dr. Fry evaluated the same material as
           Dr. Ng.

      3)  Lansing, Michigan with Dr. Douches: This project involves
           inoculated greenhouse testing of the best late blight resistant
           genotypes from the above screening projects.

3. Tuber Traits

Wild species do not produce tubers in the long days of North American summers, so their tuber traits cannot be assessed in the field.  A project was initiated in 1993 in which wild accessions are being systematically crossed with adapted (cultivated) forms to produce F₂ true seed families.  This moved the potentially valuable tuber traits of species to a background in which they can be revealed.  We will advertise these to our cooperators as they become available.

4. Frost Hardiness

In cooperation with Dr. J. Palta and YuKuang Chen, work was continued on recurrent selection for earliness, good tuber characteristics, and frost resistance.  Good progress in earliness and yield was evident this year in S. acaule - S. commersonii hybrids in the 2nd generation of crossing to very early tuberosum cultivars.  Evaluation of frost hardiness and breeding potential of somatic fusions of tuberosum with S. commersonii continued. A study to assess the impact of the ratio of sensitive to hardy genomes in interspecific crosses was also continued.

5. Tuber Calcium

Tuber calcium has been shown to be closely associated with resistance to important storage rots and other tuber quality traits.  F₂ hybrids between clones which accumulate very high calcium in a high calcium environment and clones which accumulate very little calcium in the same environment were generated and are in the process of being analyzed.  A possible link between high calcium accumulation and sprouting vigor is also being investigated.

6. RAPDs to predict need for fine screening.

This study used two populations known to be highly insect and virus resistant from species S. polytrichon and S. stoloniferum.  Since these species are facultative selfers, they might be very homogeneous, and could be expected to have little phenotypic variation within populations.  On the contrary, we found that over 20% of the bands which are polymorphic within the species are also polymorphic among individuals within the resistant population.  Therefore, resistance may not be uniform within these populations and a decision for fine screening is indicated.

7. Screening the Wild Species for Rooting Vigor

The mini-core collection was screened for rooting vigor in the screenhouse in Perlite.  Data is being gathered on relative rooting vigor.

8. Characterization for Utility Traits

The success of using Solanum germplasm for breeding is influenced by relative plant vigor, flowering, pollen shed and pollen viability.  Relative scores for these parameters were published in, ‘Elite Selections of Tuber-bearing Solanum Species Germplasm’.  Characterization of the collection for these traits continued in 1997.

F.  Inter-genebank Collaboration

The Association of Potato Intergenebank Collaborators (APIC) has initiated a joint research project to investigate the effects of seed increases on the genetic integrity of germplasm conserved ex situ, and whether germplasm in genebanks still represents the in situ populations from which they were collected.  Two papers were published on the first two phases of this project (see publications by staff).  Work on the third phase, finding factors which predict the patterns of diversity among accessions, nears completion.  New samples of S. jamesii were collected in Utah, Colorado and New Mexico, expanding the range of our research samples and adding unique germplasm to the genebank.  The first direct evidence of ancient use of potatoes in North America was gathered in cooperation with Dr. Linda Scott-Cummings.  Solanum jamesii was determined to be the source of starch grains from a mano in central New Mexico, and the charred remain from a hearth in NW Colorado.  Graduate student Alfonso del Rio conducted two additional experiments using Solanum sucrense.  The first showed that a "mystery" accession (lacking origin data) was not a duplicate of any of the sucrense already in the collection.  The second study revealed sampling techniques needed to differentiate heterogeneous Solanum species population using RAPDs.

4.  USEFULNESS OF FINDINGS

NRSP-6's purpose is to provide a ready source of raw materials, technology and information which support potato enhancement, breeding and research in the US and around the world.  Thus, one way the success of NRSP-6 can be measured is by the use of NRSP-6 germplasm in the pedigrees of new, improved potato cultivars.  Another is in the use of NRSP-6 stocks in more basic research programs which also ultimately contribute to human utilization of the potato crop, these being reflected in publications.

Two cultivar and three germplasm releases were published in the American Potato Journal in 1997: ‘Mainestay’, ‘NorDonna’, ‘ND2858-1’(CPB resistance), ‘B0718-3’, and ‘B0767-2’(both late blight resistance).  All are known to have wild species in their pedigrees.

Section 6 lists 83 papers, one abstract, and  four theses which report the use of NRSP-6 Solanum introductions this year.

5.  WORK PLANNED FOR 1998

Dr. Spooner will participate in a collecting expedition to Peru.

Evaluation experiments will be continued on Solanum species for the following traits: frost hardiness,  rooting vigor, tuber calcium, late blight resistance, hormone mutants, glycoalkaloids, and fertility in heat stress.

The general objective of NRSP-6 to promote and facilitate potato research and  breeding will be pursued by continuing high quality service with respect to introduction, preservation, classification, evaluation, and distribution of potato germplasm to clients in the U.S. and around the world.

We will continue APIC intergenebank research projects determining the cause of observed differences in situ and genebank accessions, and correlations of geographic/habitat data with partitioning of diversity.

An APIC meeting is planned for summer 1999 in India.

6.  PUBLICATIONS ISSUED DURING THE YEAR

A.  Publications issued by NRSP-6 Personnel

Castillo, R. and D.M. Spooner.  1997   Phylogenetic relationships of wild potatoes, Solanum series Conicibaccata (sect. Petota).  Syst. Bot. 22:45-83.

Miller, J.T. and D.M. Spooner.  1997.  Introgression of Solanum chacoense (Solanum sect. Petota) upland populations reexamined.  Syst. Bot. 21:461-475.

Peralta, I.E., H.E. Ballard Jr., and D.M. Spooner.  1997.  “Waxy” gene intron phylogeny of tomatoes, Solanum subsect. Lycopersicum (Solanaceae).  Am. J. Bot. Suppl.  84:222.  (Abstract).

Rio, A.H. del, J.B. Bamberg, and Z. Huaman.  1997.  Assessing changes in the genetic diversity of potato gene banks.  1. Effects of seed increase.  Theor. Appl. Genetics 95(1/2):191-198.

Rio, A.H. del, J.B. Bamberg, Z. Huaman, A. Salas, and S.E. Vega.  1997.  Assessing changes in the genetic diversity of potato gene banks.  2. In situ vs ex situ.  Theor. Appl. Genet. 95(1/2):199-204.

Rodriguez, A. and D.M. Spooner.  1997.  Chloroplast DNA analysis of Solanum bulbocastanum and S. cardiophyllum, and evidence for the distinctiveness of S. cardiophyllum subsp.  ehrenbergii (sect. Petota).  Syst. Bot. 22:31-43.

Spooner, D.M. and R. Castillo.  1997.  Reexamination of series relationships of South American wild potatoes (Solanaceae: Solanum sect. Petota): evidence from chloroplast DNA restriction site variation.  Am. J. Bot. 84:671-685.

Spooner, D.M., M.L. Ugarte, and P.W. Skroch.  1997.  Species boundaries and interrelationships of two closely related sympatric diploid wild potato species, Solanum astleyi and S. boliviense based on RAPDs.  Theor. Appl. Genet. 95:764-771.

B.  Journal Articles and Abstracts Reporting Research with NRSP-6 Stocks

      (Note: Publications from previous years are included if missed in previous Annual Reports.)

Balbyshev, N.F. and J.H. Lorenzen.  1997.  Hypersensitivity and egg drop, a novel mechanism of host-plant resistance to Colorado potato beetle (Coleoptera: Chrysomelidae).  J. Econ. Entomol. 90:652-657.

Barone, A.  1996.  Characterization by RFLP markers of interspecific Solanum hybrids forming 2n gametes.  Rivista di Agronomia 39(1):58-62.

Birhman, R.K. and M. Cappadocia.  1997.  Ploidy of anther culture derived plants of Solanum chacoense Bitt.  Indian J. Exp. Bio. 35(2):200-202.

Borkowska, M., K. Kleczkowski, A. Pawetczak, and B. Wielgat.  1995.  Transformation of diploid potato with an Agrobacterium tumefaciens binary vector system:  II. Stability of transformation in tubers, micropropagated and greenhouse grown plants.  Acta Physiol. Plant. 17(3):275-280.

Bouafia, S., N. Jelti, G. Lairy, A. Blanc, E. Bonnel, and J. Dereuddre.  1996.  Cryopreservation of potato shoot tips by encapsulation-dehydration.  Potato Research 39(1):69-78.

Brigneti, G., J. Garcia-Mas, and D.C. Baulcombe.  1997.  Molecular mapping of the potato virus Y resistance gene Ry_sto in potato.  Theor. Appl. Genet. 94(2):198-203.

Carputo, Domenico, Teodoro Cardi, Mario Speggiorin, Astolfo Zoina, and Luigi Frusciante.  1997.  Resistance to blackleg and tuber soft rot in sexual and somatic interspecific hybrids with different genetic background.  Am. Potato J. 74(3):161-172.

Cho HyunMook, Ahn Soo Yong, and Om YoungHyun.  1996. Characteristics of the floral organs in the progenies of 4x Solanum tuberosum x 2x S. phureja and pollen development of their male sterile dihaploids.  J. Korean Soc. Hort. Sci. 37(2):232-237.

Conicella, C., G. Genualdo, A. Errico, L. Frusciante, and L.M. Monti.  1996.  Meiotic restitution mechanisms and 2n pollen formation in a Solanum tuberosum dihaploid and in dihaploid x wild species hybrids.  Plant Breeding 115:157-161.

Deahl, K.  1996.  Germplasm research provides arsenal for protecting world food supplies of potato and wheat from disease threats.  Diversity 12(2):8-10.

Dorel, C., N. Hugouvieux-Cotte-Pattat, J. Robert-Baudouy, and E. Lojkowska.  1996.  Production of Erwinia chrysanthemi  pectinases in potato tubers showing high or low level of resistance to soft-rot.  Euro. J. Pl. Path. 102(6):511-517.

Douches, D.S., D. Maas, K. Jastrzebski, and R.W. Chase.  1996.  Assessment of potato breeding progress in the USA over the last century.  Crop Science 36(6):1544-1552.

Douches, David S., William W. Kirk, Kazimierz Jastrzebski, Christopher Long, and Ray Hammerschmidt.  1997.  Susceptibility of potato varieties and advanced breeding lines (Solanum tuberosum L.) to Phytophthora infestans (Mont.) de Bary in greenhouse screenings.  Am. Potato J. 74(2):75-86.

Flanders, K.L., E.B. Radcliffe, and J.G. Hawkes.  1997.  Geographic distribution of insect resistance in potatoes.  Euphytica 93(2):201-221.

Fonseca, M.E.N., V.L.A. Marinho, D.C. Monte-Neshich, and L.S. Boiteux.  1996.  Survey for beet western yellow luteovirus as a major component of the potato leaf roll disease in central Brazil.  Plant Disease 80(9):1079.

Frusciante, L., D. Carputo, M. Biagetti, and C. Ceoloni.  1996.  Advanced cytogenetic techniques for the transfer of genes for biotic stress resistance in Solanum and Triticum species.  In: Proceedings of the workshop: Plant breeding for resistance to biotic stresses: physiological and molecular bases, Monsampolo del Tronto, Italy, 19-20 May, 1994.  Petria 6(Suppl.1):219-232.

Fry, W.E. and S.B. Goodwin.  1997.  Resurgence of the Irish potato famine fungus.  BioScience 47(6):363-371.

Goth, R. W. and E.W. Goins.  1997.  Potato Carlavirus S (PVS) resistance of potato clone B6603-12.  Am. Potato J. 74(4):277-281.

Goth, R. W. and K.G. Haynes.  1997.  The germplasm release of B0718-3 and B0767-2: Two late blight resistant potato clones.  Am. Potato J. 74(5):337-345.

Hamalainen, J.H., K.N. Watanabe, J.P.T. Valkonen, A. Arihara, R.L. Plaisted, E. Pehu, L. Miller, and S.A. Slack.  1997.  Mapping and marker-assisted selection for a gene for extreme resistance to potato virus Y.  Theor. Appl. Genet. 94(2):192-197.

Hamernik, A.J. and R.E. Hanneman, Jr.  1997.  Using wild species to improve potato chip color from cold storage.  The Badger Common’Tater 49(2):42-46.

Hanzlik, M.W., G.G. Kennedy, D.C. Sanders, and D.W. Monks.  1997.  Response of European corn borer (Ostrinia nubilalis, Hubner) to two potato hybrids selected for resistance to Colorado potato beetle.  Crop Pro. 16(5):487-490.

Hawkes, J.G.  1997.  A database for wild and cultivated potatoes.  Euphytica 93(2):155-161.

He, Y., L. GengGuang, and Z. L.Ying.  1996.  Mesophyll protoplast culture and plantlet regeneration from wild species of potato.  J. Tropical & Subtropical Botany 4(3):72-74.

Heijden, G.W.A.M. van der and R.G. van den Berg.  1997.  Quantitative assessment of corolla shape variation in Solanum sect. Petota by computer image analysis.  Taxon 46(1):49-64.

Helgeson, J.  1997.  Potatoes once again, under fungal attack.  Agric. Research 45(5):10-13.

Horvath, J.  1994.  Reaction of Solanum stoloniferum to cucumber mosaic cucumovirus.  Acta Phytopath. et Entomol. Hungarica  29(1-2):105-108.

Irzykowski, W., T. Rorat, and J. Jakubiec.  1996.  Analysis of cold resistance in wild and cultivated potato species.  Acta Physiol. Plant. 18(3):217-221.

Jackson, S., J. Gascon, E. Carrera, E. Monte, and S. Prat.  1997.  Cloning and expression analysis of a gene that shows developmental regulation upon tuberization in potato.  Plant Molecular Biology 33(1):169-174.

Jackson, S.A. and R.E. Hanneman, Jr.  1996.  Studies on the crossability relationships between potato varieties and related wild species.  Biotechnology Risk Assessment: USEPA/USDA/Environment Canada/Agriculture and Agri-Food Canada.  University of Maryland, College Park, Maryland.  p. 270-277.

Jacobs, A.  1996.  Molecular analysis of cold resistance in Chilean potato species.  A minor field study.  Working paper - Internatl Rural Dev. Centre, Swedish Univ. of Agric. Sciences No. 305, 15 pp.

Jain, S.M., S.K. Sopory, and R.E. Veilleux (Eds.)  1997.  In vitro haploid production in higher plants.  Volume 5: oil, ornamental and miscellaneous plants.  Dordrecht, Netherlands; Kluwer Academic Publishers.  256 pp.

Janssen, G.J.W., A. van Norel, B. Verkerk-Bakker, and R. Janssen.  1996.  Resistance to Meloidogyne chitwoodi, M. fallax and M. hapla in wild tuber-bearing Solanum spp.  Euphytica 92(3):287-294.

Janssen, G.J.W., A. van Norel, R. Janssen, and J. Hoogendoorn.  1997.  Dominant and additive resistance to the root-knot nemataodes Meloidogyne chitwoodi and M. fallax in Central American Solanum species.  Theor. Appl. Genet. 94(5):692-700.

Janssen, G.J.W., A. van Norel, B. Verkerk-Bakker, R. Janssen, and J. Hoogendoorn.  1997.  Introgression of resistance to root-knot nematodes from wild Central American Solanum species into S. tuberosum ssp. tuberosum.  Theor. Appl. Genet. 95(3):490-496.

Kang, S. and D.J. Hannapel.  1995.  Nucleotide sequences of novel potato (Solanum tuberosum L.) MADS-box cDNAs and their expression in vegetative organs.  Gene 166(2):329-330.

Kang, S. and D.J. Hannapel.  1996.  A novel MADS-box gene of potato (Solanum tuberosum L.) expressed during the early stages of tuberization.  Plant Molecular Biology 31(2):379-386.

Kasha, K.J., Q. Yao, E. Simion, T. Hu, and R. Oro.  1995.  Production and application of doubled haploids in crops.  In: Induced mutations and molecular techniques for crop improvement.  Proceedings, Vienna, Austria, 19-23 June 1995:23-37.

Kreike, C.M. and W.J. Stiekema.  1997.  Reduced recombination and distorted segregation in a Solanum tuberosum (2x) x S. spegazzinii (2x) hybrid.  Genome 40(2):180-187.

Liu J., U. Seul, and R. Thompson.  1997.  Cloning and characterization of a pollen-specific cDNA encoding a glutamic-acid-rich protein (GARP) from potato Solanum berthaultii.  Plant Molecular Biology 33(2):291-300.

Liu, T.H.A., L.C. Stephens, and D.J. Hannapel.  1996.  Expression of a chimeric proteinase inhibitor II-GUS gene in transgenic Solanum brevidens plants.  J. Plant Phys. 149(5):533-538.

Liu, T.H.A., D.J. Hannapel, and L.C. Stephens.  1997.  Induction of cathepsin D inhibitor gene expression in response to methyl jasmonate.  J. Plant Phys. 150(3):279-282.

Lorenzen, James H. and Nikolay F. Balbyshev.  1997.  ND2858-1: A useful source of resistance to the Colorado potato beetle.  Am. Potato J. 74(5):331-335.

Magalhaes Morais, O. and C.A.B. Pereira Pinto.  1996.  Selection for yield, tuber specific gravity and high 2n pollen production in potato hybrids between Solanum tuberosum L. and the wild species Solanum chacoense Bitt.  Brazilian J. Genet. 19(3):459-463.

Maine, M.J. de.  1995.  The effects of inbreeding on the parental values of potato dihaploids.  Annals of Applied Biology 127(1):151-156.

Maine, M.J. de.  1996.  An assessment of true potato seed families of Solanum phureja.  Potato Research 39(3):323-332.

Maseulli, R.W. and E.L. Camadro.  1997.  Crossability relationships among wild potato species with different ploidies and Endosperm Balance Numbers (EBN).  Euphytica 94(2):227-235.

McGrath, J.M., S.M. Wielgus, and J.P. Helgeson.  1996.  Segregation and recombination of Solanum brevidens synteny groups in progeny of somatic hybrids with S. tuberosum: intragenomic equals or exceeds intergenomic recombination.  Genetics 142(4):1335-1348.

Moehs, C.P., P.V. Allen, M. Friedman, and W.R. Belknap.  1997.  Cloning and expression of solanidine UDP-glucose glucosyltransferase from potato.  Plant J. 11(2):227-236.

Novy, R. G., R. H. Johansen, G. A. Secor, B. L. Farnsworth, J. H. Lorenzen, N. C. Gudmestad, and E. T. Holm.  1997.  Nordonna: A red-skinned potato cultivar with wide adaptability.  Am. Potato J. 74(1):31-37.

Pandey, S.K. and P.K. Gupta.  1995.  Comparison of andigena and tuberosum for enhancing TPS production.  J. Indian Potato Assoc. 22:122-128.

Podgaetskii, A.A.  1995.  Resistance of the tubers of some potato species to Phytophthora and selection of sources of the trait.  Tsitologiya i Genetika 29(6):26-35.

Qu, D., Z. DeWei, M.S. Ramanna, and E. Jacobsen.  1996.  A comparison of progeny from diallel crosses of diploid potato with regard to the frequencies of 2n-pollen grains.  Euphytica 92(3):313-320.

Ran, Y. and D. ChaoXi.  1996.  Heterosis and genetic analysis of yield and tuber characters of 4x hybrids from 2x-2x, 4x-2x and 2x-4x crosses in potato.  Acta Agr. Sinica 22(6):745-749.

Reeves, A.F., G.A. Porter, T.M. Work, D.H. Lambert, A.A.Davis, and E.S. Plissey.  1997.  Mainestay: A high-yielding, round white potato variety for fresh market.  Am. Potato J. 74(4):255-263.

Rivard, S.R., M. Cappadocia, and B.S. Landry.  1996.  A comparison of RFLP maps based on anther culture derived, selfed, and hybrid progenies of Solanum chacoense.  Genome 39(4):611-621.

Sanford, L.L.  1997.  Tuber yields and specific gravities in Solanum tuberosum populations recurrently selected for resistance to potato leafhopper.  Am. Potato J. 74(2):65-73.

Sanford, L.L., R.S. Kobayashi, K.L. Deahl, and S.L. Sinden.  1997.  Diploid and tetraploid Solanum chacoense genotypes that synthesize leptine glycoalkaloids and deter feeding by Colorado potato beetle.  Am. Potato J. 74(1):15-21.

Sikinyi, E., D.J. Hannapel, P.M. Imerman, and H.M. Stahr.  1997.  Novel mechanism for resistance to Colorado potato beetle in wild Solanum species.  J. Econ. Entomol. 90:689-696.

Silhavy, D., A Szentesi, and Z. Banfalvi.  1996.  Solanum chacoense lines with different alkaloid contents -- a potential source of genes involved in leptine synthesis.  Acta Agronomica Hungarica 44(2):113-120.

Sim, S. K., S. M. Ohmann, and C. B.S. Tong.  1997.  Comparison of polyphenol oxidase in tubers of Solanum tuberosum and the non-browning tubers of S. hjertingii.  Am. Potato J. 74(1):1-13.

Simko, I., S. McMurry, H.-M. Yang, A. Manschot, P.J. Davies, and E.E. Ewing.  1997.  Evidence from polygene mapping for a causal relationship between potato tuber dormancy and abscisic acid content.  Pl. Physiol. 115:1453-1459.

Sint Jan, V. van, G. Laublin, R.K. Birhman, and M. Cappadocia.  1996.  Genetic analysis of leaf explant regenerability in Solanum chacoense.  Plant Cell, Tissue & Organ Culture 47(1):9-13.

Sonnino, A. and M. di Vito.  1996.  Defence mechanisms of plants against parasitic animals and selection for resistance.  In: Proceedings of the workshop: Plant breeding for resistance to biotic stresses: physiological and molecular bases, Monsampolo del Tronto, Italy, 19-20 May 1994.  Petria 6(Supp. 1):243-259.

Steinbach, P. and H. Oertel.  1995.  Selection of virus- and nematode-resistant  Solanum tuberosum L. seedlings.  1.  Selection for hypersensitivity resistance of potatoes to potatao virus S through artificial infection of seedlings.  Potato Research 38(4):407-411.

Trognitz, B., G. Forbes, and B. Hardy.  1995.  Resistance to late blight of potato from wild species.  CIP Circular 21(1):6-9.

Tucci, M., D. Carputo, G. Bile, and L. Frusciante.  1996.  Male fertility and freezing tolerance of hybrids involving Solanum tuberosum haploids and diploid Solanum species.  Potato Research 39(3):345-353.

Valkonen, J.P.T., R.A.C. Jones, S.A. Slack, and K.N. Watanabe.  1996.  Resistance specificities to viruses in potato: standardization of nomenclature.  Plant Breeding 115(6):433-438.

Vallin, K., G.P. Savage, A.J. Conner, K.E. Hellenas, and C. Branzell.  1996.  Glycoalkaloids in a somatic hybrid between Solanum brevidens and cultivated potato.  Proceedings of the Nutrition Society of New Zealand 21:130-136.

Valverde, R., T. H.H. Chen, and P. H. Li.  1998.  Frost hardiness and cold acclimation in Solanum species (Chapter 6).  In:  Paul H. Li and Tony Chen, (Eds.), Plant Cold Hardines: molecular biology, biochemistry and physiology, Plenum, NewYork-London, pp. 380.

Van den Berg, J.H., E.E. Ewing, R.L. Plaisted, S. McMurry, and M.W. Bonierbale.  1996.  QTL analysis of potato tuber dormancy.  Theor. Appl. Genet. 93(3):317-324.

Van den Berg, R.G., N. Groendijk-Wilders, and J.P. Kardolus.  1996.  The wild ancestors of cultivated potato: the brevicaule-complex.  Acta Botanica Neerlandica 45(2):157-171.

Vazquez, A., G. Gonzalez, F. Ferreira, P. Moyna, and L. Kenne.  1997.  Glycoalkaloids of Solanum commersonii Dun. ex Poir.  Euphytica 95(2):195-201.

Voort, J.N.A.M.R. van der, P. van Zandvoort, H.J. van Eck, R.T. Folkertsma, R.C.B. Hutten, J. Draaistra, F.J. Gommers, E. Jacobsen, J. Helder, and J. Bakker.  1997.  Use of allele specificity of comigrating AFLP markers to align genetic maps from different potato genotypes.  Mol. Gen. Genet. 255(4):438-337.

Wang, W., D. Takezawa, and B.W. Poovaiah.  1996.  A potato cDNA encoding a homologue of mammalian multidrug resistant P-glycoprotein.  Plant Molecular Biology 31(3):683-687.

Yencho, G.C., J.A.A. Renwick, J.D. Steffens, and W.M. Tingey.  1994.  Leaf surface extracts of Solanum berthaultii Hawkes deter Colorado potato beetle feeding.  J. Chem. Ecology 20(5):991-1007.

C.  Theses Reporting Research with NRSP-6 Stocks

Chacon-Acosta, M. G.  1997.  Inheritance of the resistance to Globodera rostochiensis pathotype Ro2 in potato.  M.S. Thesis.  Cornell University, Ithaca, New York.  87 pp.

Janssen, G.J.W.  1997.  Resistance to root-knot nematodes, Meloidogyne spp., in potato.  Ph.D. Thesis.  Wageningen Agricultural University, Wageningen, Netherlands.  111 pp.

Kardolus, J. P.  1997.  A biosystematic analysis of Solanum acaule.  Ph.D. Thesis. Wageningen Agricultural University, Wageningen, Netherlands.  110 pp.

Rai, S.  1996.  Inheritance of covalently-bound phosphate in starch of Solanum phureja x Solanum stenotonum.  M.S. Thesis.  North Dakota State University, Fargo, North Dakota.  80 pp.

7.  APPROVED

            A. R. Mosley, Chairman, Technical Committee                  Date

            R. L. Lower, Lead Administrative Advisor                         Date