Showing papers by "International Potato Center published in 2008"
TL;DR: The origin of Western European populations are identified with high accuracy from a single restricted area in the extreme south of Peru, located between the north shore of the Lake Titicaca and Cusco, with important consequences for the control of this pest and the development of quarantine measures.
Abstract: Native to South America, the potato cyst nematode Globodera pallida is one of the principal pests of Andean potato crops and is also an important global pest following its introduction to Europe, Africa, North America, Asia and Oceania. Building on earlier work showing a clear south to north phylogeographic pattern in Peruvian populations, we have been able to identify the origin of Western European populations with high accuracy. They are all derived from a single restricted area in the extreme south of Peru, located between the north shore of the Lake Titicaca and Cusco. Only four cytochrome b haplotypes are found in Western Europe, one of them being also found in some populations of this area of southern Peru. The allelic richness at seven microsatellite loci observed in the Western European populations, although only one-third of that observed in this part of southern Peru, is comparable to the allelic richness observed in the northern region of Peru. This result could be explained by the fact that most of the genetic variability observed at the scale of a field or even of a region is already observed at the scale of a single plant within a field. Thus, even introduction via a single infected potato plant could result in the relatively high genetic variability observed in Western Europe. This finding has important consequences for the control of this pest and the development of quarantine measures.
115 citations
TL;DR: In this paper, the authors applied digital soil mapping in a 13,500 km2 study area in Kenya with the main aim to create a reconnaissance soil map to assess clay and soil organic carbon contents in terraced maize fields.
Abstract: Digital soil mapping techniques appear to be an interesting alternative for traditional soil survey techniques. However, most applications deal with (semi-)detailed soil surveys where soil variability is determined by a limited number of soil forming factors. The question that remains is whether digital soil mapping techniques are equally suitable for exploratory or reconnaissance soil surveys in more extensive areas with limited data availability. We applied digital soil mapping in a 13,500 km2 study area in Kenya with the main aim to create a reconnaissance soil map to assess clay and soil organic carbon contents in terraced maize fields. Soil spatial variability prediction was based on environmental correlation using the concepts of the soil forming factors equation. During field work, 95 composite soil samples were collected. Auxiliary spatially exhaustive data provided insight on the spatial variation of climate, land cover, topography and parent material. The final digital soil maps were elaborated using regression kriging. The variance explained by the regression kriging models was estimated as 13% and 37% for soil organic carbon and clay respectively. These results were confirmed by cross-validation and provide a significant improvement compared to the existing soil survey.
97 citations
TL;DR: In this paper, high performance liquid chromatography with diode array detection (HPLC-DAD) was performed to characterize nonanthocyanin phenolic compounds in three different colored mashua genotypes.
77 citations
TL;DR: Golden bread is a good source of β-carotene and is economically viable when the price ratio of wheat flour to raw orange-fleshed sweet potato root is at least 1.5.
Abstract: BackgroundOrange-fleshed sweet potato is an efficacious source of vitamin A. Substituting wheat flour with orange-fleshed sweet potato in processed products could reduce foreign exchange outlays, c...
74 citations
TL;DR: The results indicate that any efforts to engineer pathogen-derived RNA silencing-based resistance to SPCSV and SPVD in sweetpotato should not rely on p22 as the transgene, and provides the first example of intraspecific variability in gene content of the family Closteroviridae.
Abstract: Sweet potato chlorotic stunt virus (genus Crinivirus) belongs to the family Closteroviridae, members of which have a conserved overall genomic organization but are variable in gene content. In the bipartite criniviruses, heterogeneity is pronounced in the 3'-proximal region of RNA1, which in sweet potato chlorotic stuat virus (SPCSV) encodes two novel proteins, RNase3 (RNase III endonuclease) and p22 (RNA silencing suppressor). This study showed that two Ugandan SPCSV isolates contained the p22 gene, in contrast to three isolates of the East African strain from Tanzania and Peru and an isolate of the West African strain from Israel, which were missing a 767 nt fragment of RNA1 that included the p22 gene. Regardless of the presence of p22, all tested SPCSV isolates acted synergistically with potyvirus sweet potato feathery mottle virus (SPFMV; genus Potyvirus, family Potyviridae) in co-infected sweetpotato plants (Ipomoea batatas), which greatly enhanced SPFMV titres and caused severe sweetpotato virus disease (SPVD). Therefore, the results indicate that any efforts to engineer pathogen-derived RNA silencing-based resistance to SPCSV and SPVD in sweetpotato should not rely on p22 as the transgene. The data from this study demonstrate that isolates of this virus species can vary in the genes encoding RNA silencing suppressor proteins. This study also provides the first example of intraspecific variability in gene content of the family Closteroviridae and may be a new example of the recombination-mediated gene gain that is characteristic of virus evolution in this virus family.
71 citations
TL;DR: In this paper, the temporal development of cocoa-gliricidia carbon (C) stocks and soil organic carbon (SOC) were investigated in Napu and Palolo Valleys of Central Sulawesi, Indonesia.
Abstract: In a false-time series, the temporal development of cocoa–gliricidia carbon (C) stocks and soil organic carbon (SOC) were investigated in Napu and Palolo Valleys of Central Sulawesi, Indonesia. As a first step, the Functional Branch Analysis (FBA) method was used to develop allometric equations for the above- and below-ground growth of cocoa and gliricidia. FBA resulted in shoot–root ratios of 2.54 and 2.05 for cocoa and gliricidia, respectively. In Napu and Palolo, the trunk diameter and carbon levels per gliricidia tree were always much greater than that of cocoa. The highest aerial carbon levels were attained at year four in Napu (aerial cocoa–gliricidia = 20,745.2 kg C ha−1) and at year five in Palolo (aerial cocoa–gliricidia = 38,857.0 kg C ha−1). After years four or five, however, the reduced stocking density of gliricidia attributed to a loss of aerial C. During the time spans in question, SOC remained fairly stable though slightly decreasing in Napu and slightly increasing in Palolo. The SOC harbored a vastly greater amount of system C (one-half and one-third of SOC in the 0–15 cm stratum in Napu and Palolo, respectively) relative to tree components. Eight years (Napu) or 15 years (Palolo) after conversion of a rainforest to cocoa–gliricidia agroforestry caused an 88% and 87% reduction of aerial C-stocks in Napu and Palolo, respectively.
68 citations
TL;DR: High levels of resistance to accumulation of SPCSV could not prevent development of synergistic sweet potato virus disease in those transgenic plants also infected with SPFMV.
Abstract: SUMMARY
Sweetpotato chlorotic stunt virus (SPCSV; genus Crinivirus, family Closteroviridae) is one of the most important pathogens of sweetpotato (Ipomoea batatas L.). It can reduce yields by 50% by itself and cause various synergistic disease complexes when co-infecting with other viruses, including sweetpotato feathery mottle virus (SPFMV; genus Potyvirus, family Potyviridae). Because no sources of true resistance to SPCSV are available in sweetpotato germplasm, a pathogen-derived transgenic resistance strategy was tested as an alternative solution in this study. A Peruvian sweetpotato landrace ‘Huachano’ was transformed with an intron-spliced hairpin construct targeting the replicase encoding sequences of SPCSV and SPFMV using an improved genetic transformation procedure with reproducible efficiency. Twenty-eight independent transgenic events were obtained in three transformation experiments using a highly virulent Agrobacterium tumefaciens strain and regeneration through embryogenesis. Molecular analysis indicated that all regenerants were transgenic, with 1–7 transgene loci. Accumulation of transgene-specific siRNA was detected in most of them. None of the transgenic events was immune to SPCSV, but ten of the 20 tested transgenic events exhibited mild or no symptoms following infection, and accumulation of SPCSV was significantly reduced. There are few previous reports of RNA silencing-mediated transgenic resistance to viruses of Closteroviridae in cultivated plants. However, the high levels of resistance to accumulation of SPCSV could not prevent development of synergistic sweet potato virus disease in those transgenic plants also infected with SPFMV.
68 citations
TL;DR: In this article, the authors developed and applied a "minimum-data" methodology to assess ex ante the economic viability of adopting dual-purpose sweet potato in Vihiga district, western Kenya.
64 citations
TL;DR: In this paper, the 3′-terminal ∼1,800 nucleotide sequences of 17 potyvirus samples collected from the six main sweet potato-producing areas of Peru over the past 20 years were determined and analyzed.
Abstract: Several potyviruses are found infecting sweet potato (Ipomoea batatas) in Peru, of which sweet potato feathery mottle virus (SPFMV, genus Potyvirus) is the most common. However, sequence data for these viruses are not available from Peru. In this study, the 3′-terminal ∼1,800 nucleotide sequences of 17 potyvirus samples collected from the six main sweet potato-producing areas of Peru over the past 20 years were determined and analyzed. Results of sequence comparisons and phylogenetic analysis showed that three of the four recognized SPFMV strain groups, including the East African strain, are established in Peru as well as two other potyviruses: sweet potato virus G (SPVG) and sweet potato virus 2 (SPV2). The analysis further revealed that SPFMV, SPVG and SPV2 are related and form an Ipomoea-specific phylogenetic lineage within the genus Potyvirus and identified for the first time recombination events between viruses from different strain groups of SPFMV.
61 citations
TL;DR: The results demonstrate the presence of distinct molecular and biochemical drought responses in the two potato landraces leading to yield maintenance but differential biomass accumulation in vegetative tissues.
Abstract: Responses to prolonged drought and recovery from drought of two South American potato (Solanum tuberosum L ssp andigena (Juz & Buk) Hawkes) landraces, Sullu and Ccompis were compared under field conditions Physiological and biomass measurements, yield analysis, the results of hybridisation to a potato microarray platform (44 000 probes) and metabolite profiling were used to characterise responses to water deficit Drought affected shoot and root biomass negatively in Ccompis but not in Sullu, whereas both genotypes maintained tuber yield under water stress Ccompis showed stronger reduction in maximum quantum yield under stress than Sullu, and less decrease in stomatal resistance Genes associated with PSII functions were activated during recovery in Sullu only Evidence for sucrose accumulation in Sullu only during maximum stress and recovery was observed, in addition to increases in cell wall biosynthesis A depression in the abundance of plastid superoxide dismutase transcripts was observed under maximum stress in Ccompis Both sucrose and the regulatory molecule trehalose accumulated in the leaves of Sullu only In contrast, in Ccompis, the raffinose oligosaccharide family pathway was activated, whereas low levels of sucrose and minor stress-mediated changes in trehalose were observed Proline, and expression of the associated genes, rose in both genotypes under drought, with a 3-fold higher increase in Sullu than in Ccompis The results demonstrate the presence of distinct molecular and biochemical drought responses in the two potato landraces leading to yield maintenance but differential biomass accumulation in vegetative tissues
54 citations
10 Nov 2008
TL;DR: Phylogenetic relationships of Phytophthora infestans sensu lato in the Andean highlands of South America were examined and sequences of the cytochrome oxidase I (cox I) gene and intron 1 of ras gene suggested that P. andina might have arisen via hybridization between P.infestans and P. mirabilis.
Abstract: Phylogenetic relationships of Phytophthora infestans sensu lato in the Andean highlands of South America were examined. Three clonal lineages (US-1, EC-1, EC-3) and one heterogeneous lineage (EC-2) were found in association with different host species in genus Solanum. The EC-2 lineage includes two mitochondrial (mtDNA) haplotypes, Ia and Ic. Isolates of P. infestans sensu lato EC-2 fit the morphological description of P. infestans but are different from any genotypes of P. infestans described to date. All isolates of P. infestans sensu lato from Ecuador were amplified by a P. infestans specific primer (PINF), and restriction fragment length patterns were identical in isolates amplified with ITS primers 4 and 5. The EC-1 clonal lineage of P. infestans sensu lato from S. andreanum, S. columbianum, S. paucijugum, S. phureja, S. regularifolium, S. tuberosum and S. tuquerense was confirmed to be P. infestans based on sequences of the cytochrome oxidase I (cox I) gene and intron 1 of ras gene. The EC-2 isolates with the Ic haplotype formed a distinct branch in the same clade with P. infestans and P. mirabilis, P. phaseoli and P. ipomoeae for both cox I and ras intron 1 phylogenies and were identified as the newly described species P. andina. Ras intron 1 sequence data suggests that P. andina might have arisen via hybridization between P. infestans and P. mirabilis.
TL;DR: In this paper, the authors analyze the interaction between a research and a development institution, the International Potato Center (CIP) and CARE in Peru, and make the case that participatory research can contribute to creating a collaborative learning environment among organizations.
Abstract: Participatory research (PR) has been analyzed and documented from different points of view, with emphasis on the benefits generated for farmers. The effect of PR on organizational learning has, however, received little attention. This paper analyzes the interaction between a research and a development institution, the International Potato Center (CIP) and CARE in Peru, respectively, and makes the case that PR can contribute to creating a collaborative learning environment among organizations. The paper describes the evolution of the inter-institutional collaborative environment between the two institutions for more than a decade, including an information-transfer period (1993–1996), an action-learning period (1997–2002), and a social-learning period (2003–2007). Several lessons learned from each period are described, as are changes in institutional contexts and stakeholders’ perceptions. The case shows that research and development-oriented organizations can interact fruitfully using PR as a mechanism to promote learning, flexibility in interactions, and innovation. Interactions foster the diffusion of information and the sharing of tacit knowledge within and between organizations, which in turn influences behavior. However, the paper also argues that long-term inter-organizational interactions are needed to facilitate learning, which can be used to influence the way organizations implement their interventions in a constantly changing environment.
TL;DR: The Crop Growth Analysis indicated three important characteristics differentiating Andean tubers: the S. juzepczukii potato has a high Relative Growth Rate (RGR) and a higher leaf mass ratio but a smaller tuber yield, due to a smaller harvest index and a very low Net Assimilation Rate (NAR).
TL;DR: Staff supervisory and motivational factors were assessed in the context of an ongoing program evaluation in Haiti comparing 2 models of targeting an integrated health and nutrition program and no salient differences between the 2 program models were found.
Abstract: Staff supervisory and motivational factors were assessed in the context of an ongoing program evaluation in Haiti comparing 2 models of targeting an integrated health and nutrition program. The study objectives were to 1) understand and improve supervisory and motivational factors influencing program implementation and 2) compare these factors between the 2 program models being evaluated. Qualitative methods (focus group discussions and semistructured interviews) were used to understand factors related to supervision and motivation. Quantitative measures of supervisory and motivational factors were designed, and factor analysis was used, to develop summary scales of motivational factors and supervision. T-tests were used to compare mean scores on the scales between the 2 program models. Results from the qualitative research were discussed with program management and staff to help develop solutions to implementation bottlenecks. Staff at all levels of the program seemed motivated and generally well supervised. Constraints to motivation included perceived inadequacy of wages (before changes were made to salaries), heavy workloads, and logistical constraints. We found no salient differences between the 2 program models that could contribute to differential implementation or differences in impact. This lack of salient differences between the program models suggested that supervisory and motivational factors were unlikely to contribute to differences in impact. Assessing supervisory and motivational factors was feasible and desirable in the context of this evaluation and deepened understanding of the program context and constraints to implementation.
TL;DR: Control mortality was significantly temperature-dependent and was well described by a second-order polynomial function, with lowest mortality at 25 °C (∼20%) and highest at 16-°C (>60%).
TL;DR: The present study compares an additional replicated morphological study of the same germplasm accessions in a greenhouse environment in the high Andes of central Peru with results that support extensive reduction of species in the Solanum brevicaule complex.
Abstract: The Solanum brevicaule complex contains about 20 species of diploids (2n = 2x = 24), tetraploids (2n = 4x = 48) and hexaploids (2n = 6x = 72), distributed from central Peru south to northwestern Argentina. The complex is defined entirely by morphological similarity of its constituent members, which are very similar to each other and to some landraces of the cultivated potato, Solanum tuberosum. Conflicting taxonomic treatments are common among authors. Species boundaries within the complex have been studied with morphological phenetics from germplasm accessions planted in a field plot in the north central US, and with molecular marker data from RAPDs, low-copy nuclear RFLPs, and AFLPs. The present study compares these results with an additional replicated morphological study of the same germplasm accessions in a greenhouse environment in the high Andes of central Peru. The results support extensive reduction of species in the complex.
TL;DR: This paper used a recursive optimization model to analyze how the incorporation of charcoal production by pioneer farmers in the Peruvian Amazon rainforest would affect household net returns and the rate of deforestation at the early stage of forest colonization.
TL;DR: The Institutional Learning and Change (ILAC) Initiative emerged within the Consultative Group on International Agricultural Research (CGIAR), with the goal of strengthening learning from experience and using lessons to improve pro-poor innovation as discussed by the authors.
Abstract: SUMMARY Scores of assessments of the impacts of agricultural research have been carried out over the years. However, few appear to have been used to improve decision making and the effectiveness of research programmes. The Institutional Learning and Change (ILAC) Initiative emerged within the Consultative Group on International Agricultural Research (CGIAR), with the goal of strengthening learning from experience and using lessons to improve pro-poor innovation. It is testing approaches for expanding the contributions of impact assessment and evaluation to learning, decision making and improvement.
TL;DR: The potential for preemergence infection of potato sprouts by P. infestans in the highlands of Ecuador, where year-round aerial inoculum is present, is demonstrated and indicates a need to reconsider disease management approaches.
Abstract: Experiments were conducted to determine whether preemergence infection of potato sprouts by Phytophthora infestans occurs in the highland tropics of Ecuador. In three separate experiments in the field, P. infestans was identified on the preemerged sprouts of 49, 5, and 43% of tubers, respectively, which had been removed from soil prior to emergence. Tubers had been planted within 10 m of approximately 300-m2 plots with mature potato plants severely infected with late blight. Infection potential of potato sprouts also was evaluated in the greenhouse by applying 10-ml sporangial suspensions (50 and 250 sporangia/ml) daily for 10 days to the soil surface of pots planted with sprouted seed potato tubers. The daily inoculation rate of 50 sporangia/ml (15.9 × 103 sporangia/m2) resulted in sprout infection in 100% of inoculated pots and roughly corresponded to the sporangial deposition accumulated over 24 h in the field. Deposition had been measured at 1 m from a severely infected potato plot. Our study...
TL;DR: In countries with limited investments in research and human resources development, transdisciplinary approaches with social actors and engaged researchers can sensitize new professionals training in traditional academic contexts to the ecological–social–health problems faced by poor majorities and encourage their subsequent work on sustainability for human health.
Abstract: Transdisciplinary education on sustainability for health has been primarily developed in high-income countries, yet the need in countries with limited research and human resource investments remains urgent. Little empiric documentation of the facilitators and barriers to transdisciplinary learning in such countries has been described. We assessed transdisciplinary learning among students of different disciplines collaborating with an Ecuadorian sustainability for health research project. Six undergraduate students from four different disciplinary backgrounds were incorporated through work–study agreements with provincial university academic supervisors. Learning was fostered and monitored through participant observations by a field supervisor. Students’ learning was evaluated through subsequent in-depth interviews and visualization methods. Academic supervisor key informant and co-investigator observations aided triangulation. Qualitative data were analyzed using indicators of transdisciplinary thinking. Principal factors facilitating transdisciplinary learning were interaction with social actors, the integration of work with other disciplines, the use of alternative research techniques and methods, and the constant support of the field supervisor. Inhibiting factors included the existence of rigid academic rules, lack of training of the academic supervisors in diverse research methods, and social pressures to implement unidisciplinary foci. At the end of their link with the project, students had developed both cognitive outcomes and attitudinal values relevant to sustainable development for health. In countries with limited investments in research and human resources development, transdisciplinary approaches with social actors and engaged researchers can sensitize new professionals training in traditional academic contexts to the ecological–social–health problems faced by poor majorities and encourage their subsequent work on sustainability for human health.
TL;DR: This is the first comprehensive morphological phenetic study of the Solanum series Piurana Hawkes, to include putatively related species in ser.
Abstract: There are about 190 wild potato (Solanum L. section Petota Dumort.) species distributed from the southwestern United States to central Argentina and adjacent Chile and Uruguay. The morphological similarity of many of its constituent species has led to widely conflicting taxonomic treatments. Solanum series Piurana Hawkes is one of 21 series recognized in section Petota in the latest comprehensive taxonomic treatment by Hawkes in 1990. They are distributed from southern Colombia, south through Ecuador to central Peru. The limits of the series and validity of its constituent species are unresolved. We provide the first comprehensive morphological phenetic study of the series, to include putatively related species in ser. Conicibaccata, Cuneoalata, Ingifolia, Megistacroloba, Simplicissima, Tuberosa, and Yungasensa, through an examination 188 living germplasm accessions of 33 species, planted in replicated plots in a field station in Andean Peru. Only four morphologically well-defined groups were sup...
International Rice Research Institute1, International Maize and Wheat Improvement Center2, Bioversity International3, Empresa Brasileira de Pesquisa Agropecuária4, International Potato Center5, International Crops Research Institute for the Semi-Arid Tropics6, International Center for Agricultural Research in the Dry Areas7, Biotec8, University of the Philippines Los Baños9, University of the Philippines10, National Center for Genome Resources11, Scottish Crop Research Institute12, Cornell University13, University of British Columbia14, Simon Fraser University15, BC Cancer Agency16
TL;DR: A platform-specific middleware reference implementations of the domain model integrating a suite of public databases and software tools into a workbench to facilitate biodiversity analysis, comparative analysis of crop genomic data, and plant breeding decision making.
Abstract: The Generation Challenge programme (GCP) is a global crop research consortium directed toward crop improvement through the application of comparative biology and genetic resources characterization to plant breeding. A key consortium research activity is the development of a GCP crop bioinformatics platform to support GCP research. This platform includes the following: (i) shared, public platform-independent domain models, ontology, and data formats to enable interoperability of data and analysis flows within the platform; (ii) web service and registry technologies to identify, share, and integrate information across diverse, globally dispersed data sources, as well as to access high-performance computational (HPC) facilities for computationally intensive, high-throughput analyses of project data; (iii) platform-specific middleware reference implementations of the domain model integrating a suite of public (largely open-access/-source) databases and software tools into a workbench to facilitate biodiversity analysis, comparative analysis of crop genomic data, and plant breeding decision making.
01 Sep 2008
TL;DR: In this paper, a comparative study of interpolation of three metodologies, i.e., inverso de la distancia, kriging, co-kriging and thin plate smoothing spline, was conducted in the region of sotavento and barlovento de Mexico.
Abstract: La presente investigacion se realizo en el laboratorio de agromapas digitales de la region Golfo-Centro del Instituto Nacional de Investigaciones Forestales, Agricolas y Pecuarias en 2007. Se utilizo informacion de la precipitacion pluvial historica del periodo 1961 a 2003 del mes de septiembre, registrada en 147 estaciones meteorologicas pertenecientes a la red de estaciones del Servicio Meteorologico Nacional ubicadas dentro de una region que comprende parte del barlovento y sotavento de Mexico. El objetivo fue realizar una comparacion de cuatro metodos de interpolacion: inverso de la distancia, kriging, co-kriging y thin plate smoothing spline, de datos puntuales de precipitacion pluvial en la region de sotavento y barlovento de la Republica Mexicana. La informacion fue analizada para detectar si existe en esta region una relacion de la precipitacion pluvial con las variables de elevacion, longitud y distancia al oceano. Se observo que la superficie generada con el metodo thin plate smoothing spline fue superior al registrar el menor cuadrado medio del error de prediccion, seguido por el metodo kriging y co-kriging empleando el modelo gausiano, cabe senalar, que con co-kriging se utilizo la covariable elevacion a pesar de que no se detecto una relacion significativa entre esta variable y precipitacion pluvial. Se identifico como ultima opcion para la interpolacion de datos de precipitacion el metodo de inverso de la distancia con valor optimizado.
TL;DR: Application of a simple infrared spectroscopic protocol allowed simultaneous rapid quantification of specific nutritional components in potatoes and efficient selection of value-added potato varieties.
Abstract: Efficient selection of potato varieties with enhanced nutritional quality requires simple, rapid, accurate, and cost-effective assays to obtain tuber chemical composition information. Our objective was to develop simple protocols to determine phenolics, anthocyanins, and antioxidant capacity in polyphenolic extracts of potatoes using Fourier transform infrared spectroscopy combined with multivariate techniques. Lyophilized potato samples (23) were analyzed. Polyphenolic compounds were extracted from potatoes and applied directly applied onto a three-bounce ZnSe crystal for attenuated total reflectance measurements in the infrared region of 4000 to 700 cm−1. Robust models were generated (r ≥ 0.99) with standard error of cross-validation values of 4.17 mg gallic acid equivalent/100 g (total phenolics), 0.87 mg pelargonidin-3-glucoside/100 g (monomeric anthocyanins), and 130.8 μmol Trolox equivalent/100 g (antioxidant capacity) potato powder. In addition, classification models discriminated potato samples at...
TL;DR: A study of genetic diversity was conducted among four wild Arracacia species (A. elata, A. incisa and A. xanthorrhiza), using three accessions per species, 20 plants per accession referred to as a population, 100 morphological characters and five AFLP primer combinations producing 202 AFLP markers.
Abstract: A study of genetic diversity was conducted among four wild Arracacia species (A. elata, A. equatorialis, A. incisa and A. xanthorrhiza), using three accessions per species, 20 plants per accession referred to as a population, 100 morphological characters and five AFLP primer combinations producing 202 AFLP markers. Genetic diversity was well described using these morphological descriptors and AFLP markers. Analysis of molecular variance showed a total variation of 49.5% which was attributed to differences between species; variation between populations within species amounted for 25.8%, while variation within populations accounted for 24.6%. On the basis of morphological and molecular characteristics, accessions considered previously as A. equatorialis could be regrouped with A. xanthorrhiza. These comparisons and multivariate analysis resulted in the selection of 28 morphological characters considered as discriminant to identify the Arracacia species from Peru. According to our morphological and molecular analysis, three wild species of Arracacia genus were clearly identified: A. elata, A. incisa and A. xanthorrhiza. However, A. equatorialis which was not well identified botanically could be considered as very close to A. xanthorrhiza.
TL;DR: The data suggest a complex reticulate history of the tetraploids or the need for a broad downward reevaluation of the number of species in series Conicibaccata, a trend seen in other series of sect.
Abstract: Solanum sect. Petota (tuber-bearing wild and cultivated potatoes) are a group of approximately 190 wild species distributed throughout the Americas from the southwestern United States south to Argentina, Chile, and Uruguay. Solanum series Conicibaccata are a group of approximately 40 species within sect. Petota, distributed from central Mexico to central Bolivia, composed of diploids (2n = 2x = 24), tetraploids (2n = 4x = 48) and hexaploids (2n = 6x = 64); the polyploids are thought to be polysomic polyploids. This study initially was designed to address species boundaries of the four Mexican and Central American species of series Conicibaccata with AFLP data with the addition of first germplasm collections of one of these four species, Solanum woodsonii, as a follow-up to prior morphological, chloroplast DNA, and RAPD studies; and additional species of series Conicibaccata from South America. AFLP data from 12 primer combinations (1722 polymorphic bands) are unable to distinguish polyploid species long thought to be distinct. The data suggest a complex reticulate history of the tetraploids or the need for a broad downward reevaluation of the number of species in series Conicibaccata, a trend seen in other series of sect. Petota. Separately, through flow cytometry, we report the first ploidy level of S. woodsonii, as tetraploid (2n = 48).
TL;DR: It is suspected that the continuing molecular studies will support the synonymy of many of the wild potato species distributed from southern Mexico to central Bolivia and also includes members of related series Piurana.
Abstract: Solanum series Conicibaccata contains about 40 wild potato (section Petota) species distributed from southern Mexico to central Bolivia. It contains diploids (2n = 2x = 24), tetraploids (2n = 4x = 48) and hexaploids (2n = 6x = 72) and some polyploids are likely allopolyploids. Our morphological phenetic study in an Andean site in central Peru (12°S, 3200 m altitude) is a replicated study from one done in the north central United States (45°N, 180 m elevation) but uses more species (28 vs. 25), accessions (173 vs. 100), and morphological characters (72 vs. 45) and also includes members of related series Piurana. Both US and Peruvian studies provide phenetic support with Canonical Discriminant Analyses (but poorly if at all with Principal Components Analyses) to distinguish the following species or species groups in series Conicibaccata: 1) S. agrimonifolium and S. oxycarpum as a possible single species, and 2) S. longiconicum (tetraploids from Mexico and Central America), 3) the South American Con...
TL;DR: Strategies based on using the translaminar fungicide cymoxanil for control of potato late blight, caused by Phytophthora infestans, were compared in the highland tropics of Ecuador in three separate field experiments.
TL;DR: The result revealed that encapsulation of Foxy 2 into “Pesta” formulation did not adversely affect its virulence and efficacy even after 5 years of storage under cold conditions, representing an important attribute to support wide-scale deployment, storage, handling and delivery of Striga-mycoherbicides Pesta technology in Africa.
Abstract: An important goal for mycoherbicide research and development is to produce a viable and consistently efficacious product with a long shelf life. The efficacy of 5-year-old Pesta granules of Fusarium oxysporum Foxy 2 in comparison to freshly prepared Pesta granules in controlling the root parasitic weed Striga hermonthica was studied. Pesta granules were made by encapsulating fresh chlamydospores of Foxy 2 in a matrix composed of durum wheat-flour, kaolin, and sucrose. Samples of Pesta granules were stored at 4°C over a period of 5 years. Two g per pot (4 kg soil) of each granular preparation were incorporated pre-planting to sorghum together with Striga seeds. The application of the 5-year-old Pesta granules (2.4 × 105 Cfu g–1) as well as the freshly prepared Pesta granules (1.5 × 106 Cfu g–1) of Foxy 2 sharply reduced the total number of healthy emerged S. hermonthica shoots and/or caused severe disease on the emerged Striga plants compared to the control. None of the emerged plants reached flowering stage in Foxy 2-treated pots, whereas in the control treatment 19.2% of the Striga plants flowered. Maximum efficacy (i.e., 100% reduction in healthy emerged Striga shoots compared to the control treatment) of both Pesta preparations in controlling Striga was achieved, indicating similar potential of both old and fresh formulations. The result revealed that encapsulation of Foxy 2 into “Pesta” formulation did not adversely affect its virulence and efficacy even after 5 years of storage under cold conditions. This represents an important attribute to support wide-scale deployment, storage, handling and delivery of Striga-mycoherbicides Pesta technology in Africa.