Species concepts and relationships in wild and cultivated potatoes

Wild and cultivated potatoes (Solanum section Petota) present challenges to taxonomists arising from lack of clearly defined morphological character differences among many species, phenotypic plasticity, a range of ploidy levels from diploid to hexaploid, and hybrid speciation and introgression. Taxonomic treatments of the group have differed greatly regarding numbers of species and hypotheses of their interrelationships at the series level. Recent morphological phenetic studies and molecular studies have confirmed the general lack of clearly defined species, have shown the need to use a number of character states with overlapping ranges for species delimitation (polythetic support), and have suggested the need for the reduction of species in section Petota. Molecular studies have sometimes confirmed hypotheses of hybridization and sometimes have failed to support them. Molecular studies have suggested the need for a reconsideration of the traditionally held series concepts. Currently, section Petota contains 196 wild species and a single cultivated species, Solanum tuberosum, with eight landrace cultivar groups, exclusive of the modern cultivars that are not yet classified into cultivar groups. The number of wild species likely will decrease with future study. These points are here illustrated by (1) a discussion of published species level studies in Solanum series Longipedicellata, the Solanum brevicaule complex, and the cultivated landrace populations of potatoes; (2) reinvestigations of hybridization in S. chacoense, S. raphanifolium and S. xrechei; and (3) studies of ingroup and outgroup relationships of section Petota

Listado anotado de Solanum L. (Solanaceae) en el Peru.

The genus Solanum is among the most species-rich genera both of the Peruvian flora and of the tropical Andes in general. The present revised checklist treats 276 species of Solanum L., of which 253 are native, while 23 are introduced and/or cultivated. A total of 74 Solanum species (29% of native species) are endemic to Peru. Additional 58 species occur only in small number of populations outside Peru, and these species are here labelled as near-endemics to highlight the role Peru playes in their future protection. Species diversity is observed to peak between 2500 – 3000 m elevation, but endemic species diversity is highest between 3000 – 3500 m elevation. Cajamarca has the highest number of endemic (29 spp.) and total species (130 spp.), even when considering the effect of area. Centers of endemic species diversity are observed in provinces of Cajamarca (Cajamarca), Huaraz and Carhuaz (Ancash), and Canta and Huarochirí (Lima). Secondary centres of endemism with high concentrations of both endemics and near-endemics are found in San Ignacio and Cutervo (Cajamarca), Santiago de Chuco (La Libertad), Oxapampa (Pasco), and Cusco (Cusco). Current diversity patterns are highly correlated with collection densities, and further collecting is needed across all areas, especially from Arequipa, Ayacucho, Puno, Ancash, Huánuco, Amazonas and Cajamarca, where high levels of species diversity and endemism are indicated but only a few collections of many species are known.Solanum L. es uno de los géneros que posee una alta riqueza de especies dentro de la flora peruana y dentro de los Andes tropicales en general. Presentamos una lista revisada de 276 especies de Solanum para el Perú, de estas 253 son nativas, mientras que 23 son introducidas y/o cultivadas. Un total de 74 especies de Solanum (29% de las especies nativas) son endémicas de Perú. Además 58 especies se encuentran solamente en pequeñas poblaciones fuera del Perú, y estas especies están designadas aquí como casi endémicas para destacar el rol importante del Perú en la futura protección de estas especies. El pico de diversidad de especies es observado entre 2500 – 3000 m de elevación, pero la diversidad de especies endémicas es más alta entre 3000 – 3500 m. Cajamarca tiene el más alto número de especies (130 spp.) y de especies endémicas (29 spp.), incluso si se considera el efecto del área. Centros de diversidad de especies endémicas se localizan en las provincias de Cajamarca (Cajamarca), Huaraz y Carhuaz (Ancash), Canta y Huarochirí (Lima). Centros de endemismos secundarios con una alta concentración tanto de especies endémicas y de casi endémicas se encuentran en San Ignacio y Cutervo (Cajamarca), Santiago de Chuco (La Libertad), Oxapampa (Pasco), y Cusco (Cusco): Los actuales patrones de diversidad están altamente correlacionados con la densidad de colecciones, por lo que es necesario una mayor colecta en todas las regiones, especialmente en Arequipa, Ayacucho, Puno, Ancash, Huánuco, Amazonas y Cajamarca, donde se indican altos niveles de diversidad y endemismo de especies, pero de las cuales existen pocas colecciones

Molecular markers for genebank management

In the last decade, the use of DNA markers for the study of crop genetic diversity has become routine, and has revolutionized biology. Increasingly, techniques are being developed to more precisely, quickly and cheaply assess genetic variation. These techniques have changed the standard equipment of many labs, and most germplasm scientists are expected to be trained in DNA data generation and interpretation. The rapid growth of new techniques has stimulated this update of IPGRI's Technical Bulletin No. 2, ”Molecular tools in plant genetic resources conservation: a guide to the technologies” (Karp et al. 1997b). Our goal is to update DNA techniques from this publication, to show examples of their applications, and to guide genebank researchers towards ways to maximize their use. This bulletin reviews basic qualities of molecular markers, their characteristics, the advantages and disadvantages of their applications, and analytical techniques, and provides some examples of their use.There is no single molecular approach for many of the problems facing genebank managers, and many techniques complement each other. However, some techniques are clearly more appropriate than others for some specific applications. In an ideal situation, the most appropriate marker(s) can be chosen irrespective of time or funding constraints, but in other cases the choice of marker(s) will depend on constraints of equipment or funds. The purpose of this publication is to explain the characteristics of different markers and guide to their use through a number of real examples that represent well informed choices. What is most important is to choose a marker that can appropriately address well-defined questions through good experimental design, ideally leading to peer-reviewed scientific publications. Experimental design has many definitions depending on the type of question being asked and on the field of science addressed. We use the term here in a very general way to cover all aspects of planning an experiment, including a clear definition of the question being addressed; knowledge of prior studies addressing the question; proper choice of molecular markers and of data used to address the question; knowledge of the characteristics, strengths and weaknesses of the data; sources of unexpected variation in the data; how much data are needed; proper methods to analyze the data; and limits to conclusions you can make from the results. One of the most important considerations before beginning any experiment is to address proper experimental design. Improper experimental design can make the work inconclusive, misleading, insignificant, and most likely unpublishable. Similarly, improvements in experimental design can change an uninspired study to a highly significant one with little to no increase in time and funds. Poor experimental design can waste significant resources and damage the reputation and impact of your genebank. It is beyond the scope of any publication to outline all possible pitfalls that can lead to poorly designed experiments, analyses or conclusions, and different considerations of proper experimental design need to be made in particular fields. This technical bulletin outlines some basic considerations regarding molecular marker types and analyses to lead the reader. There is no substitute, however, for basic knowledge of the biological questions being addressed, knowledge of the taxonomic group under consideration and a thorough literature review to ensure that similar work has not been done before. If limitations of any type hinder genebank and germplasm managers with regards to these factors, collaboration or consultation with experts is well worth the effort. Excellent reviews of methodology and data interpretation are presented in Weising et al. (1995), Hillis et al. (1996), Staub et al. (1996), Hillis (1997), Karp et al. (1997a,b) and Avise (2004). Hamrick and Godt (1997) present a review of isozyme data; Doebley (1992), Clegg (1993b) and Spooner and Lara-Cabrera (2001) present a review of molecular data for plant genetic resources and crop evolution; Bruford and Wayne (1993), Wang et al. (1994), Gupta et al. (1996), Powell et al. (1996a) and Weising et al. (1998) of microsatellite data; Wolfe and Liston (1998) on Polymerase Chain Reaction (PCR) related data. Schlötterer (2004) reviews the history and relative utility of different molecular marker types. Sytsma and Hahn (1997) present reviews of molecular studies in crop and non-crop plants. Some information from Spooner and Lara-Cabrera (2001) for crop diversity studies was used and updated; Spooner et al. (2003) was used for taxonomy studies. An overview of the main marker techniques and their comparative qualities is presented in the section titled, ”Overview of molecular technologies”. Applications of molecular techniques in genebank management and crop breeding are the subject of the following sections. The section titled, ”Future challenges” focuses on the current developments in molecular marker applications and future challenges that could result from these developments. Elements of experimental design are discussed throughout and some basic aspects of data analysis are discussed in ”Genebank management”

US Cosmic Visions: New Ideas in Dark Matter 2017: Community Report

This white paper summarizes the workshop "U.S. Cosmic Visions: New Ideas in Dark Matter" held at University of Maryland on March 23-25, 2017

Assessment of Psychophysiological Differences of West Point Cadets and Civilian Controls Immersed within a Virtual Environment

Abstract. An important question for ecologically valid virtual environments is whether cohort characteristics affect immersion. If a method for assessing a cer-tain neurocognitive capacity (e.g. attentional processing) is adapted to a cohort other than the one that was used for the initial normative distribution, data ob-tained in the new cohort may not be reflective of the neurocognitive capacity in question. We assessed the psychophysiological impact of different levels of immersion upon persons from two cohorts: 1) civilian university students; and 2) West Point Cadets. Cadets were found to have diminished startle eyeblink amplitude compared with civilians, which may reflect that cadets experienced less negative affect during the scenario in general. Further, heart rate data re-vealed that Cadets had significantly lower heart rates than Civilians in the “low ” but not “high ” immersion condition. This suggests that “low ” immersion conditions may not have the ecological validity necessary to evoke consistent affect across cohorts

Resistência a Septoria lycopersici em espécies de Solanum (Secção Lycopersicon) e em progênies de S. lycopersicum × S. peruvianum

Septoria leaf spot (Septoria lycopersici) is one of the major fungal diseases of tomatoes (Solanum lycopersicum) in tropical and subtropical regions with humid climates and/or in areas cultivated under sprinkler irrigation systems. Sources of resistance have been found in accessions of Solanum (section Lycopersicon) species. However, many of the described sources are not effective under Brazilian conditions. The objective of this work was to evaluate wild and cultivated Solanum (section Lycopersicon) germplasm to S. lycopersici isolates. A collection of 124 accessions was initially evaluated under greenhouse conditions. Ten accessions were highly resistance (HR), whereas 33 were classified as having a resistant (R) response to S. lycopersici isolates. Field evaluation was also conducted with a sub-set of accessions identified as either HR or R in the greenhouse experiment. This field evaluation confirmed greenhouse tests and indicated the presence of some potential sources of rate-reducing resistance. One highly resistant and eight resistant S. habrochaites accessions were identified as being resistant under both conditions, confirming that this wild species is one of the most promising sources of resistance to S. lycopersici. Five new sources with high levels of resistance were found in S. peruvianum accessions (PI-306811, CNPH-1036, LA-1910, LA-1984 and LA-2744). One accession derived from an interspecific cross between S. lycopersicum and S. peruvianum was also found to be highly resistant and might be useful to introgress resistance factors from this wild species into cultivated tomato germplasm. However, additional breeding efforts will be necessary to introgress into the cultivated tomato the resistance factors identified in other S. peruvianum accessions due to the presence of natural crossing barriers between the two species.A mancha-de-septória (Septoria lycopersici) é importante doença fúngica do tomateiro (Solanum lycopersicum) em áreas tropicais e subtropicais com alta umidade ou quando esta hortaliça é cultivada sob irrigação por aspersão. Fontes de resistência têm sido encontradas em germoplasma de Solanum (secção Lycopersicon). No entanto, muitas das fontes descritas não funcionam nas condições brasileiras. Avaliou-se uma coleção de germoplasma de tomate cultivado e selvagem (Solanum secção Lycopersicon) visando identificar novas fontes de elevada resistência. Uma coleção de 124 acessos foi inicialmente avaliada sob condições de casa de vegetação. Somente dez acessos foram classificados como altamente resistentes e 33 foram classificados como resistentes. Um ensaio de campo foi também conduzido com um subconjunto de acessos promissores identificados no primeiro experimento. Foi confirmada a resposta da maioria dos acessos avaliados em casa de vegetação e indicou a presença de fontes de resistência capazes de reduzir a taxa de progresso da doença. Um acesso de S. habrochaites com elevada resistência e oito acessos resistentes foram identificados, confirmando que esta espécie representa uma das mais promissoras fontes de genes de resistência a S. lycopersici. Cinco novas fontes com elevados níveis de resistência foram identificadas em acessos da espécie S. peruvianum (PI-306811, CNPH-1036, LA-1910, LA-1984 e LA-2744). Um acesso, derivado de cruzamento interespecífico entre S. lycopersicum e S. peruvianum também mostrou-se altamente resistente e poderá ser útil na introgressão deste(s) gene(s) em germoplasma de tomateiro cultivado. No entanto, esforços adicionais de melhoramento serão necessários para transferir para o tomateiro cultivado os fatores de resistência identificados em outros acessos de S. peruvianum, uma vez que existem barreiras naturais de cruzamentos entre estas duas espécies