valeria negri | University of Perugia (original) (raw)
Papers by valeria negri
Biodiversity and Conservation, 2010
Over the last two decades, the importance of conserving genetic resources has received increasing... more Over the last two decades, the importance of conserving genetic resources has received increasing attention. In this context the role of home gardens as repositories of biological diversity has been acknowledged but still a comprehensive, interdisciplinary investigation of their agro-biodiversity is lacking. Home gardens, whether found in rural or urban areas, are characterized by a structural complexity and multifunctionality which enables the provision of different benefits to ecosystems and people. Studies carried out in various countries demonstrate that high levels of inter-and intra-specific plant genetic diversity, especially in terms of traditional crop varieties and landraces, are preserved in home gardens. Families engage in food production for subsistence or small-scale marketing and the variety of crops and wild plants provides nutritional benefits. At the same time, home gardens are important social and cultural spaces where knowledge related to agricultural practices is transmitted and through which households may improve their income and livelihoods. The present article summarizes available literature on the biological and cultural significance of agro-biodiversity in home gardens. It discusses future constraints and opportunities in home garden research, in the prospect of defining and promoting their role in conservation of agricultural biodiversity and cultural heritage.
Genetic Resources and Crop Evolution, 2002
Thirty-one Phaseolus vulgaris L. and fivePhaseolus coccineus L. landraces reproduced on-farm were... more Thirty-one Phaseolus vulgaris L. and fivePhaseolus coccineus L. landraces reproduced on-farm werefound in central Italy. They were mostly grown by elderly farmers who usuallyselect for a certain type of seed. Different varieties are often grown in eachlocation and on each farm. They are maintained on-farm because of a local marketrequest for high quality products or because of sticking to traditional familyuse in cooking (21.2 and 75.8% of recorded cases, respectively). Three AFLPprimer combinations were used to assess genetic variation among collectedmaterials, a wild accession of P.vulgaris and commercial varieties of both species. Theyrevealed a quite high percentage of polymorphism (90.2% of polymorphic bands asan average). A wide genetic variation was observed among collected materials andeach accession showed a unique pattern of polymorphism. WithinP. vulgaris, landraces werediscriminated in two main subgroups, the former including the accessions fromthe Mediterranean area around the Lake Trasimeno and the latter includingaccessions from the humid Mediterranean area within the Appennine Mountains.These findings demonstrate the peculiar genetic identity of the landracesstudied also in relationship to human and environmental selection pressures.Possible on-farm conservation strategies are briefly discussed in relationshipto the information collected.
Molecular Ecology, 2007
Little is known about the organization of landrace diversity and about the forces that shape and ... more Little is known about the organization of landrace diversity and about the forces that shape and maintain within-and among-landrace population diversity. However, this knowledge is essential for conservation and breeding activities. The first aim of this study was to obtain some insight into how variation has been sculptured within a cultivated environment and to identify the loci that potentially underlie selective effects by using a Phaseolus vulgaris L. landrace case study whose natural and human environment and morpho-physiological traits are known in detail. The second aim of this study was to define an appropriate on-farm conservation strategy which can serve as a model for other populations. The farmers' populations of this threatened landrace were examined with 28 single sequence repeat molecular markers. The landrace appears to be a genetically structured population in which substantial diversity is maintained at the subpopulation level (62% of the total variance). Evidence of locus-specific selective effects was obtained for five of the 13 loci-differentiating subpopulations. Their role is discussed. Our data suggest that a complex interaction of factors (differential microenvironmental selection pressures by farmers and by biotic and abiotic conditions, migration rate and drift) explains the observed pattern of diversity. Appropriate on-farm conservation of a structured landrace requires the maintenance of the entire population.
Euphytica, 2008
Isatis tinctoria L. (woad) is a dye plant whose cultivation is increasing because of its adaptabi... more Isatis tinctoria L. (woad) is a dye plant whose cultivation is increasing because of its adaptability to marginal conditions and increasing demand for natural products. Suitable breeding schemes need to be set up in order to obtain woad varieties for each proposed environment. Presently, no data about the reproductive system are available. The effects of selfing and crossing on setting and progeny vigour were assessed. Results showed the existence of an outcrossing system in I. tinctoria. Obligate self-pollinated plants produced fewer siliques (7.1 g per plant) with lower weight (6.0 mg) and lower seed germinability (8.2%) than outcrossing plants (44.1 g, 8.0 mg and 46.0% for each character, respectively). Self-pollinated progenies also generally showed lower vigour than outcrossing progenies.
Theoretical and Applied Genetics, 2008
The study of phenotypic and genetic diversity in landrace collections is important for germplasm ... more The study of phenotypic and genetic diversity in landrace collections is important for germplasm conservation. In addition, the characterisation of very diversified materials with molecular markers offers a unique opportunity to define significant marker-trait associations of biological and agronomic interest. Here, 50 tomato landraces (mainly collected in central Italy), nine vintage and modern cultivars, and two wild outgroups were grown at two locations in central Italy and characterised for 15 morpho-physiological traits and 29 simple sequence repeat (SSR) loci. The markers were selected to include a group of loci in regions harbouring reported quantitative trait loci (QTLs) that affect fruit size and/or shape (Q-SSRs) and a group of markers that have not been mapped or shown to have a priori known linkage (NQ-SSRs). As revealed by univariate and multivariate analyses of morphological data, the landraces grouped according to vegetative and reproductive traits, with emphasis on fruit size, shape and final destination of the product. Compared to the low molecular polymorphism reported in tomato modern cultivars, our data reveal a high level of molecular diversity in landraces. Such diversity has allowed the inference of the existence of a genetic structure that was factored into the association analysis. As the proportion of significant associations is higher between the Q-SSR subset of markers and the subset of traits related to fruit size and shape than for all of the other combinations, we conclude that this approach is valid for establishing true-positive marker-trait relationships in tomato.
ABSTRACT A surely underestimated picture of the Italian germplasm could be summarized in the foll... more ABSTRACT A surely underestimated picture of the Italian germplasm could be summarized in the following numbers: Phaseolus spp. (5831), Pisum sativum (4657), Vicia faba (2302), Vigna spp. (948), Cicer arietinum (369), Lens culinaris (348), Lathyrus spp. (347), Lupinus spp. (188), but without doubt more accessions are conserved (and characterized) because the absence of a national Gene Bank. This puzzled condition has positive and negative consequences: several collecting missions have been done also in the recent past at regional level and still other are planned in the future, with the opportunity to find other interesting landraces or local varieties, but the costs for their conservation and the risks of duplication of the material is quite significant. Regeneration of accessions is done routinely but according to different priorities; for example, breeding materials are not completely kept after the end of a project, and for this reason in the institutions devoted to grain legume improvement the dimension of germplasm is fluctuating. In the last years a great impulse in the germplasm preservation was given by several projects carried out with the aim to preserve and promote traditional foods and markets, funded by the Italian Ministry of Agriculture or at different level by local institutions. A significant picture of the "Byzantine" situation of the Italian germplasm could arise from the following contributions written by 6 diverse experts working in different institutions. This report has not the pretension to cover all the researches ongoing on grain legumes in Italy, because studies are surely more in numbers and results, since grain legumes are the second most characterized group of plants among the genetic Italian experts.
Theoretical and Applied Genetics, 2011
Phaseolus coccineus L. is closely related to P. vulgaris and is the third most important cultivat... more Phaseolus coccineus L. is closely related to P. vulgaris and is the third most important cultivated Phaseolus species. Little is known about the patterns of its diversity. In this work, a representative collection of its worldwide diversity was initially developed. The collection includes 28 wild forms (WFs) and 52 landraces (LRs) from Mesoamerica (the crop domestication area), and 148 LRs from Europe (where the crop was introduced in the sixteenth century). The collection was studied by using 12 SSR molecular markers that were developed for the P. vulgaris genome. They were proved to be effective and reliable in P. coccineus in this work. Fourteen LRs of P. dumosus (previously identified as a subspecies of P. coccineus) were also studied. The genetic diversity, population structure and phylogenetic relationships were investigated. The results indicate that: (a) the European and Mesoamerican gene pools are clearly differentiated, (b) a certain reduction of diversity occurred with introduction into Europe, and (c) the Mesoamerican LRs (P. dumosus included) and WFs are closely related and are connected by a high gene flow. Inferences on the domestication process of P. coccineus are also presented. This study provides a picture of the genetic diversity distribution and outcomes with introduction into the Old World, which was not available before. It also underlines that the genetic diversity of both WFs and LRs is an important source for Phaseolus spp. breeding programs and deserves to be preserved in situ and ex situ.
Biodiversity and Conservation, 2010
Over the last two decades, the importance of conserving genetic resources has received increasing... more Over the last two decades, the importance of conserving genetic resources has received increasing attention. In this context the role of home gardens as repositories of biological diversity has been acknowledged but still a comprehensive, interdisciplinary investigation of their agro-biodiversity is lacking. Home gardens, whether found in rural or urban areas, are characterized by a structural complexity and multifunctionality which enables the provision of different benefits to ecosystems and people. Studies carried out in various countries demonstrate that high levels of inter-and intra-specific plant genetic diversity, especially in terms of traditional crop varieties and landraces, are preserved in home gardens. Families engage in food production for subsistence or small-scale marketing and the variety of crops and wild plants provides nutritional benefits. At the same time, home gardens are important social and cultural spaces where knowledge related to agricultural practices is transmitted and through which households may improve their income and livelihoods. The present article summarizes available literature on the biological and cultural significance of agro-biodiversity in home gardens. It discusses future constraints and opportunities in home garden research, in the prospect of defining and promoting their role in conservation of agricultural biodiversity and cultural heritage.
Genetic Resources and Crop Evolution, 2002
Thirty-one Phaseolus vulgaris L. and fivePhaseolus coccineus L. landraces reproduced on-farm were... more Thirty-one Phaseolus vulgaris L. and fivePhaseolus coccineus L. landraces reproduced on-farm werefound in central Italy. They were mostly grown by elderly farmers who usuallyselect for a certain type of seed. Different varieties are often grown in eachlocation and on each farm. They are maintained on-farm because of a local marketrequest for high quality products or because of sticking to traditional familyuse in cooking (21.2 and 75.8% of recorded cases, respectively). Three AFLPprimer combinations were used to assess genetic variation among collectedmaterials, a wild accession of P.vulgaris and commercial varieties of both species. Theyrevealed a quite high percentage of polymorphism (90.2% of polymorphic bands asan average). A wide genetic variation was observed among collected materials andeach accession showed a unique pattern of polymorphism. WithinP. vulgaris, landraces werediscriminated in two main subgroups, the former including the accessions fromthe Mediterranean area around the Lake Trasimeno and the latter includingaccessions from the humid Mediterranean area within the Appennine Mountains.These findings demonstrate the peculiar genetic identity of the landracesstudied also in relationship to human and environmental selection pressures.Possible on-farm conservation strategies are briefly discussed in relationshipto the information collected.
Molecular Ecology, 2007
Little is known about the organization of landrace diversity and about the forces that shape and ... more Little is known about the organization of landrace diversity and about the forces that shape and maintain within-and among-landrace population diversity. However, this knowledge is essential for conservation and breeding activities. The first aim of this study was to obtain some insight into how variation has been sculptured within a cultivated environment and to identify the loci that potentially underlie selective effects by using a Phaseolus vulgaris L. landrace case study whose natural and human environment and morpho-physiological traits are known in detail. The second aim of this study was to define an appropriate on-farm conservation strategy which can serve as a model for other populations. The farmers' populations of this threatened landrace were examined with 28 single sequence repeat molecular markers. The landrace appears to be a genetically structured population in which substantial diversity is maintained at the subpopulation level (62% of the total variance). Evidence of locus-specific selective effects was obtained for five of the 13 loci-differentiating subpopulations. Their role is discussed. Our data suggest that a complex interaction of factors (differential microenvironmental selection pressures by farmers and by biotic and abiotic conditions, migration rate and drift) explains the observed pattern of diversity. Appropriate on-farm conservation of a structured landrace requires the maintenance of the entire population.
Euphytica, 2008
Isatis tinctoria L. (woad) is a dye plant whose cultivation is increasing because of its adaptabi... more Isatis tinctoria L. (woad) is a dye plant whose cultivation is increasing because of its adaptability to marginal conditions and increasing demand for natural products. Suitable breeding schemes need to be set up in order to obtain woad varieties for each proposed environment. Presently, no data about the reproductive system are available. The effects of selfing and crossing on setting and progeny vigour were assessed. Results showed the existence of an outcrossing system in I. tinctoria. Obligate self-pollinated plants produced fewer siliques (7.1 g per plant) with lower weight (6.0 mg) and lower seed germinability (8.2%) than outcrossing plants (44.1 g, 8.0 mg and 46.0% for each character, respectively). Self-pollinated progenies also generally showed lower vigour than outcrossing progenies.
Theoretical and Applied Genetics, 2008
The study of phenotypic and genetic diversity in landrace collections is important for germplasm ... more The study of phenotypic and genetic diversity in landrace collections is important for germplasm conservation. In addition, the characterisation of very diversified materials with molecular markers offers a unique opportunity to define significant marker-trait associations of biological and agronomic interest. Here, 50 tomato landraces (mainly collected in central Italy), nine vintage and modern cultivars, and two wild outgroups were grown at two locations in central Italy and characterised for 15 morpho-physiological traits and 29 simple sequence repeat (SSR) loci. The markers were selected to include a group of loci in regions harbouring reported quantitative trait loci (QTLs) that affect fruit size and/or shape (Q-SSRs) and a group of markers that have not been mapped or shown to have a priori known linkage (NQ-SSRs). As revealed by univariate and multivariate analyses of morphological data, the landraces grouped according to vegetative and reproductive traits, with emphasis on fruit size, shape and final destination of the product. Compared to the low molecular polymorphism reported in tomato modern cultivars, our data reveal a high level of molecular diversity in landraces. Such diversity has allowed the inference of the existence of a genetic structure that was factored into the association analysis. As the proportion of significant associations is higher between the Q-SSR subset of markers and the subset of traits related to fruit size and shape than for all of the other combinations, we conclude that this approach is valid for establishing true-positive marker-trait relationships in tomato.
ABSTRACT A surely underestimated picture of the Italian germplasm could be summarized in the foll... more ABSTRACT A surely underestimated picture of the Italian germplasm could be summarized in the following numbers: Phaseolus spp. (5831), Pisum sativum (4657), Vicia faba (2302), Vigna spp. (948), Cicer arietinum (369), Lens culinaris (348), Lathyrus spp. (347), Lupinus spp. (188), but without doubt more accessions are conserved (and characterized) because the absence of a national Gene Bank. This puzzled condition has positive and negative consequences: several collecting missions have been done also in the recent past at regional level and still other are planned in the future, with the opportunity to find other interesting landraces or local varieties, but the costs for their conservation and the risks of duplication of the material is quite significant. Regeneration of accessions is done routinely but according to different priorities; for example, breeding materials are not completely kept after the end of a project, and for this reason in the institutions devoted to grain legume improvement the dimension of germplasm is fluctuating. In the last years a great impulse in the germplasm preservation was given by several projects carried out with the aim to preserve and promote traditional foods and markets, funded by the Italian Ministry of Agriculture or at different level by local institutions. A significant picture of the "Byzantine" situation of the Italian germplasm could arise from the following contributions written by 6 diverse experts working in different institutions. This report has not the pretension to cover all the researches ongoing on grain legumes in Italy, because studies are surely more in numbers and results, since grain legumes are the second most characterized group of plants among the genetic Italian experts.
Theoretical and Applied Genetics, 2011
Phaseolus coccineus L. is closely related to P. vulgaris and is the third most important cultivat... more Phaseolus coccineus L. is closely related to P. vulgaris and is the third most important cultivated Phaseolus species. Little is known about the patterns of its diversity. In this work, a representative collection of its worldwide diversity was initially developed. The collection includes 28 wild forms (WFs) and 52 landraces (LRs) from Mesoamerica (the crop domestication area), and 148 LRs from Europe (where the crop was introduced in the sixteenth century). The collection was studied by using 12 SSR molecular markers that were developed for the P. vulgaris genome. They were proved to be effective and reliable in P. coccineus in this work. Fourteen LRs of P. dumosus (previously identified as a subspecies of P. coccineus) were also studied. The genetic diversity, population structure and phylogenetic relationships were investigated. The results indicate that: (a) the European and Mesoamerican gene pools are clearly differentiated, (b) a certain reduction of diversity occurred with introduction into Europe, and (c) the Mesoamerican LRs (P. dumosus included) and WFs are closely related and are connected by a high gene flow. Inferences on the domestication process of P. coccineus are also presented. This study provides a picture of the genetic diversity distribution and outcomes with introduction into the Old World, which was not available before. It also underlines that the genetic diversity of both WFs and LRs is an important source for Phaseolus spp. breeding programs and deserves to be preserved in situ and ex situ.