Solanum burtonii,a new wild potato species from Ecuador

Before 1960 knowledge of the wild potato species from Ecuador was very limited. We knew only three tuber bearing species:Solanum paucijugum Bitt.,S. pichinchense Bitt. et Sodiro andS. solisii Hawkes. However, during the last two decades information has increased greatly with the researches of Donovan S. Correll and the writer. So, to the aforementioned species we must addS. albornozii, S. cyanophyllum, S. regularifolium, S. suffrutescens andS. minutifoliolum found by Correll;S. calacalinum, S. correlli andS. tundalomense discovered by me. With this opportunity, I present another new wild potato species from Ecuador,Solarium burtonii, named in honor of Prof. Dr. W. Glynn Burton as a recognition to his outstanding contributions in the field of potato physiology.     

Solanum neovavilovii: A new wild potato species from Bolivia

Regions such as Mexico, where important sources of resistance to late blight of potato have been found, have also been widely explored for wild potatoes. In contrast, Bolivia has received little attention. Although more than 50 names have been published for wild species from Bolivia, a great majority of these only constitute synonyms. Nevertheless, our exploratory work shows that finding new species is still possible in the isolated and remote localities of this country as demonstrated by the present new species,Solarium neovavilovii (Sect. Petota), dedicated to the great Russian scientist Nicolai I. Vavilov. Solatium neovavilovii is a diploid species (2n = 2x = 24 chromosomes) and belongs to the Conicibaccata series. Its preferred habitat is in thickets of “Ceja de Selva,” an ecological formation which is humid, cold, and frequently foggy, typical of the eastern region of the Andes. Its type locality has an altitude of 3000 m. This species is closely related toSolanum limbaniense Ochoa from south east Perú.     

Solanum sawyeri,a new wild potato species from the Peruvian tropics

During my ongoing study of the systematics of the Peruvian wild tuberbearing Solanums I have reviewed some rare and interesting collections made in the past which previously had seemed very difficult to classify correctly. After reviewing and comparing some of these specimens with other collections gathered in the main herbaria of U.S.A. and Europe, I am convinced of the existence of some still undescribed species such as the one I am presenting here under the name ofSolanum sawyeri in honor of Dr. Richard Leander Sawyer, promoter and founder of The International Potato Center located at Lima, Peru. Solanum sawyeri, is acclimated to the warm humid tropics of Southern Peru. It grows in forests of the low land regions of the Eastern province of Urubamba in the Department of Cusco and thereafter might serve as a source of breeding material for those who want to select potato cultivars for the low land tropics. This species belongs to the series Tuberosa with 2n = 2× = 24 chromosomes.     

Solanum peloquinianum: A new wild potato species from the Peruvian Andes

After having collected a vast amount of indigenous potato cultivars, The International Potato Center has recently intensified its explorations in the Andes of South America. The intent is to collect and utilize in its breeding programs the diversity of wild species that are found profusely distributed in the mountainous regions of South America. During the course of this work, several new species are being identified. Following we present a diploid species which is new to science.     

Solanum bill-hookeri: New wild potato species from Peru

There is presented the original diagnosis ofSolanum bill-hookeri from the series Tuberosa (Sect. Petota), a new wild tuber-bearing diploid (2n=2x=24) species from Peru, named in honor of Dr. William J. Hooker.     

Solanum antacochense,a new wild Peruvian species

The largest concentration of wild tuber-bearingSolanums in the Western Hemisphere is located in the Andean region of Perú. However, in spite of the many potato collecting expeditions which have carried out extensive field work in the past, there still remain new species to be presented to science for the first time.Solanum antacochense, from the series tuberosa, a diploid species (2n = 2x = 24 chromosomes) native to Perú described here, is one of them.     

Stolon characteristics and tuber initiation in a wild potato species (Solanum demissum Lindl.)

Summary Solanum demissum Lindl. is a short-day dependent, tuber-bearing species. In vitro propagated genetically identical plants were grown under long-day (16 h) conditions at 20°C day and 15°C night temperatures. Subsequently, from day 0 onwards, plants were exposed to shortday (10 h) conditions and grown in a multi-compartment system that allowed stolon initiation, stolon branching, stolon growth and tuber initiation to be monitored twice weekly. These frequent measurements resulted in detailed life-histories of all 841 stolon tips formed until day 46. Tuber initiation was irregular under these well-defined conditions; at day 46 only 106 stolon tips showed subapical swelling. This irregularity of tuber initiation was also observed within stolons. It is therefore suggested that tuber initiation depends on characteristics of the stolon or stolon branch, and several such characteristics were analyzed to obtain information on their potentially determining role in tuber initiation. No positive correlations were found between subapical swelling and branching order, stolon and stolon-branch age, longitudinal growth rates of stolons and stolon branches, and attachment of the stolon to the main stem.     

Inheritance study of tuber glycoalkaloids in a wild potato,Solanum chacoense bitter

Studies were made of segregating families from crosses between accessions of Solanumchacoense Bitter differing in steroid glycoalkaloids. The major glycoalkaloids were isolated from tubers and identified by thin-layer chromatography. Simple segregation ratios of 3:1 in an F₂ and 1:1 in backcrosses were obtained for the presence:absence of solanine, chaconine, and commersonine. To explain the simultaneous segregation of the three glycoalkaloids, we tentatively hypothesize that: (1) solanine and commersonine are determined by alternative codominant alleles at a single gene locus; (2) a major gene for chaconine segregates independently of the solanine/commersonine locus; and (3) a recessive gene linked with the commersonine allele is epistatic to the chaconine gene, causing the production of β-chaconine instead of the usual α-chaconine. The F₂ distribution could be fit to the ratio 3:6:3:1:2:1, seen as combining the 1:2:1 segregation of solanine: solanine + commersonine: commersonine and the 3:1 segregation of presence: absence of chaconine.     

Resistance to potato virus M in certain wild potato species

Summary Resistance to PVM has been found in some progenies ofSolanum gourlayi Haw., andS. spegazzinii Bitt. Clones from two progenies ofS. gourlayi, INTA 7330 and 7356, remained uninfected even after repeated graft inoculation.     

The significance of wild species for potato breeding

Summary The writer discusses the selection work performed at the Max-Planck-Institute at Cologne-Vogelsang. Attention was particularly concentrated on finding crosses with wild species resistant to diseases and plagues. The writer discusses in turn the results obtained with resistance toPhytophthora infestans, Alternaria solani, Rhizoctonia solani, Streptomyces scabies, Spongospora subterranea, Synchytrium endobioticum, virus diseases,Heterodera rostochiensis and Colorado beetle. He also refers to various difficulties that occur in crosses with wild species.

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Zusammenfassung Der Verfasser bespricht die Selektionsarbeit, die im Max-Planck-Institut in K?ln-Vogelsang verrichtet worden ist. Die Aufmerksamkeit war vor allem darauf konzentriert, Kreuzungen mit Wildarten zu suchen, die resistent sind gegen Krankheiten und Sch?dlingsplagen. Nacheinander bespricht der Verfasser die Ergebnisse, die erreicht worden sind mit der Resistenz gegenPhytophthora infestans, Alternaria solani, Rhizoctonia solani, Streptomyces scabies, Spongospora subterranea, Synchytrium endobioticum, Viruskrankheiten,Heterodera rostochiensis und Kartoffelk?fer. Ferner nennt er einige Schwierigkeiten, die bei Kreuzungen mit Wildarten entstehen.

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Résumé L'auteur donne un exposé sur l'oeuvre sélectionnaire, entreprise à l'Institut-Max-Planck à Cologne-Vogelsang. Une attention particulière a été apportée notamment à la recherche de croisements avec des éspèces sauvages résistant aux maladies et aux pestes. L'auteur traite ensuite des résultats que donne la résistance àPhytophthora infestans, Alternaria solani, Rhizoctonia solani, Streptomyces scabies, Spongospora subterranea, Synchytrium endobioticum, maladies virologiques,Heterodera rostochiensis et au doryphore. Pour conclure, il traite de quelques difficultés que soulèvent les croisements avec des variétés sauvages.

     

Solanum correllii a new tuber bearing species from Ecuador

In spite of being a small country, Ecuador has a very rich and varied flora. In relation to the relatively small area of the country, Ecuador surely has one of the richest floras in South America. It harbors several-thousand species of the Plant Kingdom including many endemic and unique ones. Regarding Ecuadorian wild potatoes, up to now we know fourteen species, ten of which are endemic to that country. In this paper, a new species from Ecuador is described. It has been dedicated to Dr. Donovan S. Correll who is an outstanding botanist and contributor to the knowledge of tuber bearing solanums through his 1962 monograph, the only one written on the subject up to now. Due to the rough Andean Geography, there surely are in Ecuador several other new species of wild potatoes yet to be discovered.     

Species relationships between a wild tetraploid potato species,Solanum acaule bitter, and its related species as revealed by rflps of chloroplast and nuclear DNA

Solanum acaule Bitter is a wild, disomic tetraploid potato species widely distributed in the South America. In this study, species relationships between eight accessions ofS. acaule and 108 accessions of 27 morphologically closely related species were investigated using chloroplast and nuclear DNA RFLPs. Chloroplast DNA types were determined for most of the accessions based on restriction digestion patterns of entire chloroplast DNA. C type chloroplast DNA was common inS. acaule andS. albicans (a hexaploid derivative fromS. acaule), which was also found inS. megistacrolobum, S. sanctae-rosae,S. raphanifolium, and several other Peruvian species in seriesTuberosa. Nuclear DNA was analyzed by Southern hybridization with 31 single-copy RFLP probes. One hundred and thirty-four bands were scored, from which a UPGMA dendrogram was constructed to show overall similarities among accessions.Solanum acaule andS. albicans (andS. demissum) formed a cluster with a high similarity, and then, this group was clustered withS. megistacrolobum andS. sanctae-rosae. The resulting cluster was well separated from other clusters. Thus, we suggest that an initial tetrasomic tetraploid arose from eitherS. megistacrolobum orS. sanctae-rosae. Interestingly, a Mexican hexaploid speciesS. demissum showed the closest similarity toS. acaule andS. albicans, suggesting that they shared a common ancestry.     

Solanum Incamayoense: A new tuberous species of Argentina

Solarium incamayoense is described as a new wild tuber-bearing species from dept. Rosario de Lerma, prov. Salta, Argentina. This species is morphologically related toS. gourlayi Hawkes from which it differs by the shape, size and colour of the leaflets and by the habit of growth. The species is diploid (2n = 24).     

Solanum bombycinum,a new tuber-bearing tetraploid species from Bolivia

It is probable that the wild potatoes from Bolivia are the least known of all the Andean region. Although approximately 50 species have been described from this country since Dunal, 1852, a great majority of these are synonyms. Nevertheless, in some remote and unexplored regions of Bolivia, it is still possible to find new material, as demonstrated by the new species described herein. Solanum bombycinum was found in the north-northwest part of the Department of La Paz, Province of Caupolican, at an altitude of 2000 m, living among shrubby woods in a humid lowland tropic. This wild species constitutes a particularly interesting discovery, as it represents the southern most species from South America described to date for the series Conicibaccata, and, furthermore, because its ploidy level is 2n = 4x = 48 chromosomes in a series usually having 2n = 2x = 24.     

Taxonomy and new collections of wild potato species in Central and Southern Peru in 1999

Peru contains about half of the described wild potato taxa, and many of these are not yet preserved in genebanks. This paper reports results of the second of a series of five planned collecting expeditions to Peru. Collections were made in the central Peruvian departments of Ancash, Huancavelica, La Libertad, and Lima, from March 8 to April 25,1999. They follow collections in 1998 in the southern Peruvian departments of Apurimac, Arequipa, Cusco, Moquegua, Puno, and Tacna. We collected 101 germplasm accessions, including first germplasm collections of the following 22Solanum taxa:Solanum amayanum, S. anamatophilum, S. arahuayum (lost in germplasm increase),S. augustii, S. bill- hookeri, S. cantense, S. chavinense, S. chomatophilum var. subnivale, S. chrysoflorum, S. gracilifrons, S. hapalos um, S. huarochiriense, S. hypacrarthrum, S.jalcae, S. moniliforme, S. multiinterruptum f. longipilosum, S. multiinterruptum var. machaytambinum, S. peloquinianum, S. rhombilanceolatum, S. simplicissimum, S. taulisense (lost in germplasm increase), andS. wittmackii. In addition, new collections were made of the under-collected speciesS. hastiforme (three collections). The above taxonomy is that used in planning our expedition, that we compare to a new treatment of Peruvian wild potatoes published by C. Ochoa in 1999. This paper reports the collection and new species identifications of the 1999 collections, and germplasm conservation and survival of the 1998 and 1999 collections. In addition, chromosome counts are provided for 134 accessions from the 1998 and 1999 expeditions, including first reports forS. chomatophilum var. subnivale (2n = 2x = 24),S. megistacrolobum subsp.purpureum (2n = 2x = 24), andS. multiinterruptum var.multiinterruptum f.albiflorum (2n = 2x = 24); we also report the first triploid count of an accession ofS. immite.     

Fine screening potato (Solanum) species germplasm for tuber calcium

A representative sample of the US potato germplasm collection was screened in the greenhouse for ability to accumulate tuber calcium. Germplasm with very high and very low calcium accumulation capacity has been identified by progressively screening for extremes among species, among populations (accessions), and finally among genotypes (i.e., fine screening). Among accessions, the bestS. gourlayi andmicrodontum populations averaged more than six-fold greater tuber calcium than the poorestS. kurtzianum population. When screening was performed at the genotype level, the best individuals ofgourlayi andmicrodontum had over eight-fold greater calcium than the poorestkurtzianum individual. When grown in the field, calcium levels ofS. microdontum selections were confirmed to be significantly higher thantuberosum cultivars. When selected genotypes were intercrossed and their progeny were compared to their original populations, mean tuber calcium was significantly changed in the intended direction of selection forS. kurtzianum (made lower) andS. microdontum (made higher). These stocks are expected to be useful tools for study of the genetic and physiological bases of tuber calcium accumulation, refining screening methods, and breeding improved cultivars.     

Solanum Nemorosum: A new hexaploid tuber-bearing species from Peru

Up to the present time, the only representative Peruvian hexaploid tuber-bearing wild species isSolanum acaule Bitt. var.albicans Ochoa, from the series Acaulia of theSection Tuberarium. This entity was found by the author for the first time in the paramo prairies of Porcon, Cajamarca in northern Peru. Now it is my pleasure to present again another extremely interesting new wild species,Solanum nemorosum, which is also hexaploid, that is to say with a content of 2n = 6x = 72 chromosomes. It is native also from the north of Peru and belongs to the series Conicibaccata. It occurs primarily in humid forests of shrubs or small trees.     

Screening potato (Solanum) species for male fertility under heat stress

Heat stress limits botanical seed production by inhibiting flowering, pollen production and pollen viability. Three accessions (PIs) of each of 23 diverseSolanum species were screened for stability of fertility parameters under heat stress. Seedlings were grown to flowering in temperate conditions (16–25 C), then treated with three weeks of heat stress of up to 45 C for 4–6 hours per day at midday with nighttime lows of 18 C, and compared to temperate-grown controls. A highly significant effect of species, temperature, and their interaction was detected for flowering. This means species were inherently different and heat had a general depressing effect, but the degree of that effect varied among species. While most species had little flowering in the hot house,S. commersonii andmicrodontum flowered significantly more there than in the temperate house. Of species which flowered in hot conditions, some shed no pollen and some had good shed of mostly dead pollen, but onlyS. commersonii, jamesii, kurtzianum andmegistacrolobum had good flowering, pollen shed and viability. This work is expected to contribute to the study of the genetic and physiological bases of heat stress fertility, true potato seed (TPS) breeding, and possibly improvement of tomato production under heat stress.