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James Nienhuis

An enigma in the process of domestication of many of our common vegetables is what they looked like and the speed of the process at which they were transformed from the wild progenitors to the modern cultivars. Many vegetables were either domesticated in antiquity or introduced into Europe, often by trade with Africa, the Middle East, or the Americas. Based on genetic information, we often know or can deduce center of origin and the progenitor species of our common vegetables, but we do not have a record of their early history once introduced into Europe. One window to the process of domestication of vegetables is still life art from the Renaissance period. The emphasis of the art form “natura morta” emphasized realism, which allows us to, in some cases, identify species and market classes based on accurate morphological details.

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Jesse Vorwald and James Nienhuis

Nuña beans are a type of common bean (Phaseolus vulgaris L.) native to the Andean region of South America that possess the unusual property of popping; however, little is known regarding postharvest environmental effects on popping. Seed of a photoperiod-insensitive, temperate-adapted nuña bean breeding line, ‘PB24’, was produced at the Arlington Agricultural Research Station, Arlington, WI, and evaluated in a hot air popper. The experimental design was a factorial with three levels of popping time (60, 90, and 120 s), five levels of chamber temperature (101, 146, 208, 244, and 268 °C), and eight levels of seed moisture (2.5%, 3.2%, 5.2%, 6.6%, 8.3%, 12.0%, 15.3%, and 20%). Percentage of popped seed, sufficiently expanded to shed the seedcoat, was calculated. A curvilinear decrease in popping percentage was observed with increasing seed moisture content. In contrast, a curvilinear increase in popping percentage was observed with increasing chamber temperature and popping time. Larger mean squares were observed for main effects and first-order interactions associated with seed moisture content and chamber temperature compared with popping time. A combination of seed moisture below 5%, popping chamber temperature of 244 °C, and popping time of 90 s resulted in popping percentages greater than 90%.

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Jesse Vorwald and James Nienhuis

Nuña beans are a type of common bean (Phaseolus vulgaris L.) from the Andean region of South America that possess the unique property of popping. To develop temperate-adapted nuña bean cultivars, knowledge is needed regarding the inheritance and relationships among popping characteristics and seed weight. Nuña bean landraces are often photoperiod-sensitive; thus, to obtain estimates of the genetic parameters associated with seed characteristics, populations adapted to the long days of northern temperate climates were developed. Four sets of 10 families, sampled from a temperate-adapted population, were crossed in a Design II mating design. The heritabilities of seed weight, popping percentage, and the coefficient of expansion were relatively high, 0.77 ± 0.04, 0.87 ± 0.07, and 0.74 ± 0.09, respectively. Large positive phenotypic (0.773) and additive genetic (0.539) correlations were observed between popping percentage and the coefficient of expansion. Correlations with seed weight were not significant. The results indicate that direct selection for either increased popping percentage or coefficient of expansion will simultaneously improve both traits with little or no change in seed weight.

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Gavin R. Sills and James Nienhuis

The interactive effects of genotypes, plant population densities, and harvest methods on snap bean (Phaseolus vulgaris L.) yield evaluation were investigated using a split-split plot factorial arrangement of treatments at two locations Six snap bean processing cultivars were grown at 5.5, 11, and 22 plants/m2 and harvested either by machine or by hand. Each' of three commercial seed companies provided two cultivars, one of which was described as “good” and the other as “poor” for machine harvesting. Genotype × harvest method interactions were not significant for pod count, but were significant when yield was evaluated as pod weight. This latter interaction was explained by a single-degree-of-freedom contrast of genotypes × (“good” vs. “poor” harvestability). Genotype × density and genotype × density × location interactions were significant for both pod count and weight. The density × harvest method interaction was nonsignificant for both yield variables. These results suggest that breeders can evaluate yield of genotypes using either hand or machine harvest but should use plant population densities appropriate to commercial production. Optimum plot size for snap bean yield evaluations at these locations under the various conditions imposed were estimated.

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James Nienhuis, Paul Skroch, and Steve Beebe

Nuñas are a type of common bean (Phaseolus vulgaris) that possess the unusual characteristic of popping or expanding their cotyledonary tissue when heated. Numerous landraces of nuña beans were domesticated in the Andean region of South America (Peru, Bolivia, and Ecuador) and have been grown and consumed in this region since antiquity. The practical consideration in the domestication of nuñas in the high Andes was likely due to the greater energy efficiency in cooking toasted vs. boiled seeds.The Phaseolus germplasm bank at CIAT (Centro Internacional de Agricultura Tropical) has developed a core collection of Andean beans that includes numerous nuña landraces. Based on the wide range of phaseolin types observed among nuña landraces, it has been hypothesized that nuñas may represent a greater source of genetic diversity compared to other landraces and cultivars of common bean. Eighty nuña accessions and 120 nonpopping common bean accessions were randomly sampled from the CIAT Andean germplasm core collection. The 200 accessions were characterized for 140 mapped RAPD markers. The objectives of our research were to 1) understand the genetic structure of nuña bean accessions relative to other Andean common beans, and 2) to measure the genetic distance and genetic diversity between nuña and other Andean bean populations.

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James Nienhuis*, Betsy Barnard, and Michell Sass

We have developed a series of instructional materials integrating a proven teaching tool, Wisconsin Fast Plants, with hands-on molecular techniques. Many biotechnology techniques, including genomics, have developed to a point where appropriate modifications can result in classroom accessible instructional materials that will engage students and teachers. Three “kits” have been developed or are in the process of development. Kit 1-PCR and Fast Plants. This kit is designed to provide an introduction to PCR and a link to Wisconsin Fast Plants. This kit uses a specific robust primer, which can amplify a specific sequence in Brassica rapa (Fast Plants). This kit serves as a hands-on tool to familiarize students with DNA extraction, PCR, gel electrophoresis, and analysis of PCR products. Kit 2-Genetic Diversity—`Veggie interesting'. This kit is based on the development of a specific primer, which is polymorphic between B. rapa (Fast Plants) and B. oleracea (common vegetables). In this kit, we explore the use of molecular markers and PCR to determine the species classification of various Brassica subspecies. This kit can be used to teach students about plant diversity and the use of molecular biology techniques (such as PCR) to determine how plants are related to each other. Kit 3-Genomics. The primary biological component is a simplified DNA chip (microarray) specifically designed for visualization of differential gene expression. This chip contains Arabidopsis thaliana genes that have already been characterized in our laboratory that display differential expression in seedlings grown in light vs. dark. To simplify analysis, the chip contain approximately ten genes rather than the thousands that are typically spotted on research chip.

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James Nienhuis, Steve Schroeder, and Gretchen King

An accession of the wild species of tomato, L. pennellii (Cor.) D'Arcy, LA 1077 is much more water-use efficient (WUE) than the cultivated tomato. The F1 hybrid between L. esculentum cultivar UC82 and LA 1077 was backcrossed to UC8 2 and selfed. S1 families (BC1S1) were evaluated for fruit quality characteristics at the Heinz Research Farm, Stockton, CA. Broad sense heritabilities were estimated as follows: Fruit weight, 0.52 ± .28; Soluble solids 0.56 ± .27; viscosity 0.63 ± .27; pH 0.43 ±.29 Color L 0.59 ± .27 and Color A/B ratio 0.50 ± .28. The following phenotypic correlations were observed in the BC1S1 generation between expression of soluble solids and fruit quality characteristics: Fruit weight (g), 0.15; viscosity, -0.65; pH -0.52; Color L, -0.53 and Color A/B ratio 0.02.

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Federico L. Iniguez Luy and James Nienhuis

Wisconsin Fast Plants (WFP) are small, rapid-cycling Brassica rapa populations that were developed by Paul Williams in the Dept. of Plant Pathology at the Univ. of Wisconsin, to facilitate classroom demonstration of biological principals. WFP exist as heterogenous populations, which have been selected for expression of different mutant phenotypes. Because of self-incompatibility mechanisms, it has been difficult to develop inbred lines of WFP via self-feritilization. Our objective was to inbreed a WFP population through full-sib mating. Genetic diversity was calculated for eight individuals from each of eight different WFF population, using 69 polymorphic RAPD (molecular marker) bands. The eight different WPF populatons were randomly mated (via chain crossing) for two generations. Six cycles of full-sib mating were initiated on 130 random families. After six cycles of full-sib mating, 79 families remain. The loss of families, during the process of inbreeding, may have been due to selection or drift. However, the expectation is that genetic variance will increase. The 79 inbred families express an array of different WFP phenotypes, e.g., anthocyanin pigmentation, yellow cotyledon, plant height, and seed color at different combinations in different inbred lines.

Open access

Wesley Gartner, Paul C. Bethke, Theodore J. Kisha, and James Nienhuis

Sugars, including glucose, fructose, and sucrose, contribute significantly to the flavor and consumer acceptance of snap beans (Phaseolus vulgaris L.). Sugar accumulation and changes in sugar profiles during snap bean development contribute to overall assessments of quality for breeding lines and cultivars. Developing fruit from a diverse group of four snap bean cultivars containing Andean germplasm and one Mesoamerican dry bean cultivar were sampled at 5-day intervals from 10 to 30 days after flowering over 2 years. Glucose, fructose, and sucrose in pod and seed tissue was quantified using high-performance liquid chromatography. Percent seed mass relative to pod mass increased with days after flowering, but the rate of increase was heterogeneous among cultivars. Significant differences in sugar accumulation patterns of mono- and disaccharides were observed with time of development and between pods and seeds. Glucose and fructose decreased rapidly in pods and seeds with time after flowering. In contrast, sucrose concentration increased in pod tissue but remained constant in seeds of the snap bean cultivars with time after flowering. The patterns of changes in pod and seed sugar concentrations with time after flowering were similar among all snap bean cultivars. In contrast to the snap beans, seed sucrose increased with time after flowering in the Mesoamerican dry bean cultivar Puebla 152. No year by day after flowering interactions were observed for sugar accumulation patterns or sugar concentrations. Younger snap beans had the highest sweetness index based on observed sugar concentrations, percent seed mass, and perception of relative sweetness by the human palate. Although mean sweetness varied between cultivars, the rate of decrease in sweetness with time was the same for all five cultivars. These findings indicate that variation for sweetness exists in snap beans and can be exploited by breeding to develop cultivars with a potentially more desirable, sweet flavor.

Free access

Kyle M. VandenLangenberg, Paul C. Bethke, and James Nienhuis

Sugars, including fructose, glucose, and sucrose, contribute significantly to the flavor and consumer acceptance of snap beans (Phaseolus vulgaris L.). Little is known regarding differences in sugar content among snap bean and dry bean cultivars and the patterns of sugar accumulation with increasing pod size. Alcohol–soluble sugar concentration of five snap bean cultivars and one dry bean cultivar planted in field trials was assayed throughout pod development over 2 years using high-performance liquid chromatography. Significant differences in sugar accumulation patterns and quantity were observed among cultivars. In general, fructose and glucose content decreased, whereas sucrose increased with increasing pod size in snap beans. In contrast, fructose and glucose amounts increased, whereas sucrose concentration remained unchanged with increasing pod size in the dry bean cultivar. No year-by-genotype interactions were observed for sugar accumulation patterns or sugar amount. Results indicate that sieve size No. 3 (7.34 to 8.33 mm) or No. 4 (8.33 to 9.52 mm) pods are suitable for detecting differences in sugar concentration among genotypes.