Larry J. Kuhns

Genetic bases of isozyme variation for alkaline phosphatase and glucosephosphate isomerase in Solanum.

SummaryGenetic bases of isozyme phenotypes of alkaline phosphatase (AKP) and glucosephosphate isomerase (GpI) from tuber extracts of potato species of the genus Solanum were investigated by starch gel electrophoresis. Data were obtained from reciprocal F1 matings of S. tuberosum X ssp. andigena (Juz. & Buk.) Hawkes and ssp. tuberosum X (S. phureja X S. chacoense) and BC1 matings where ssp. tuberosum was the recurrent parent. AKP and GPI are dimeric enzymes and the variation observed for each was found to be coded by single tetrasomic loci (Akp and Gpi) with three (A, A′, A″) and five (G, G′, G″, G‴, G⁗) alleles, respectively. Although the G‴ and G⁗ encoded homodimers have similar electrophoretic mobilities, the specific enzymatic activity of the G⁗ encoded homodimer is approximately 25% that of the G‴. The predictable genetic bases for these two enzymatic polymorphisms make them suitable for use as genetic markers in the potato. Chromosome mapping of the loci which encode these enzymes is now possible.

Potato cultivars: Genetic variation within putative clones

Four of five major cultivars of the potato (Solanum tuberosum L. ssp.tuberosum) from different sources were found to vary genetically. This variability was detected by an electrophoretic study of enzymatic activity for alkaline phosphatase and glucosephosphate isomerase. An examination of red cultivars from Beltsville, Md. suggests that the apparent intracultivar variability observed for Red Pontiac may be due to cultivar mislabeling rather than mutation or mitotic recombination. The results of this study raise concerns about potato cultivar certification and interpretations of some of the previous cultivar work. We suggest that a more extensive survey of intracultivar variability be carried out. Further, we suggest that these genetic markers and others could be used in cultivar identification.ResumenCuatro de cinco cultivares importantes de papa (Solanum tuberosum L. spp.tuberosum) de diferentes origenes mostraron variabilidad genética. Esta variabilidad fué determinada mediante un estudio electroforético de la actividad enzimática de fosfatasa alcalina e isomerasa glucofosfatada. Un análisis de los cultivares de color rojo de Beltsville, Md. sugiere que la variabilidad intracultivar observado en Red Pontiac podria deberse a fallas de identificación en vez de mutaciones o recombinaciones mitóticas. De acuerdo alos resultados de este estudio los autores señalan su preocupación respecto a la certificación de cultivares de papa y sobre las interpretaciones de algunos trabajos previos sobre cultivares. Sugieren que se realice un análisis más completo de la variabilidad intracultivar. Más aún, sugieren que estos marcadores genéticos, así como otros, podrian ser usados en la identificación de cultivares.

Guide to Selecting and Specifying Nursery Stock

Successfully planting of trees in urban areas is a difficult task. There are many things that must be done accurately, and a mistake in only one area can result in the failure of the plantation. Sites must be selected and evaluated thoroughly to determine if trees are appropriate for them, and if there is sufficient suitable soil to support their growth. Species that are adaptable to the site conditions must be selected and then located and purchased. The trees must be planted properly and maintained until established in the site. It is the objective of this chapter to define the factors that make a high-quality tree, and help urban tree managers locate and purchase high-quality trees for their communities.

Guide to Selecting and Specifying Quality Nursery Stock

Successfully planting trees in urban areas is a difficult task. Many things must be done right, and a mistake in only one area can result in the failure of the planting. Sites must be selected and evaluated thoroughly to determine whether trees are appropriate for them and whether there is sufficient suitable soil to support their growth. Species that are adaptable to the site conditions must be selected. The trees selected then must be located and purchased. The trees must be planted properly and maintained until established in the site. It is the objective of this chapter to define the factors that make a high-quality tree and help urban tree managers locate and purchase high-quality trees for their communities.