Erosion of genetic resources within seed genebanks: the role of seed containers

Gómez‐Campo, C.

doi:10.1017/ssr2006260

Cited by 23 publications

(27 citation statements)

References 3 publications

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“…One of the most important cultural areas of Mesoamerica is the Mayan region which has been divided into two subareas: (1) The Mayan lowlands, which includes the Yucatan Peninsula (Yucatan, Campeche and Quintana Roo) and the state of Tabasco in Mexico, the region of Peten in Guatemala and Belize; and (2) the Mayan highlands, which includes the state of Chiapas in Mexico, Guatemala (except Peten) and the western part of Honduras and El Salvador (Ruz 1981;Garza et al 1996;Sharer 1999). Within the Mayan area, evidence has been found about domestication of regionally important species such as jocote (Spondias purpurea L; Miller and Schaal 2005), scarlet runner bean (P. coccineus L.; Spataro et al 2011) and Lima beans (P. lunatus L.; Andueza-Noh et al 2013).…”

Section: Introductionmentioning

confidence: 99%

Genetic structure of Lima bean (Phaseolus lunatus L.) landraces grown in the Mayan area

Camacho-Pérez

Martínez-Castillo

Mijangos‐Cortés

et al. 2017

Genet Resour Crop Evol

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Lima bean (Phaseolus lunatus L.) is an important crop in the Mayan culture. The Mayan area, considered as a main center of Mesoamerican diversity, has been divided into two subareas: the Mayan lowlands and the Mayan highlands. The Yucatan Peninsula is part of the Mayan lowlands and holds the highest number of Lima bean landraces of Mexico, but Lima beans are in high risk of genetic erosion due to intensification of the traditional Mayan agriculture. However, information on genetic diversity of Lima beans of the Mayan highlands is lacking. By using 46 landraces collected in the Mayan area (23 from each subarea) and 73 ISSR loci (intersimple sequence repeats), we analyzed the structure, diversity and genetic relationships of Lima beans of this part of Mesoamerica. High levels of diversity (H BAY = 0.45) and genetic structure (F ST = 0.66) were found for the whole Mayan area. Genetic diversity in the Mayan lowlands was apparently higher than the Mayan highlands (H BAY = 0.44 and 0.36, respectively); but differences were not statistically significant. Genetic structure between the subareas was high (AMOVA = 30% of total variation), most landraces grouping according to their geographic origin. This study shows the importance of the Mayan culture in the diversification and conservation of Lima beans. The results provide important information that should be considered when implementing strategies to collect Lima bean landraces and planning in situ and ex situ programs to conserve these landraces in the Mayan region.

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Section: Introductionmentioning

confidence: 99%

Genetic structure of Lima bean (Phaseolus lunatus L.) landraces grown in the Mayan area

Camacho-Pérez

Martínez-Castillo

Mijangos‐Cortés

et al. 2017

Genet Resour Crop Evol

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“…Those observations have been supported by work on 195 species by Probert et al (2009), who also found that endospermous seeds tended to have shorter life spans than ex-endospermous types. However, whatever the inherent life span of orthodox seeds of individual species, it is essential that the conditions of storage [including packaging (Gómez-Campo, 2006; Walters, 2007)] are such as to maximize longevity.…”

Section: Storage Of Desiccation-tolerant Seedsmentioning

confidence: 99%

Implications of the lack of desiccation tolerance in recalcitrant seeds

2013

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A suite of interacting processes and mechanisms enables tolerance of desiccation and storage (conservation) of orthodox seeds in the dry state. While this is a long-term option under optimized conditions, dry orthodox seeds are not immortal, with life spans having been characterized as short, intermediate and long. Factors facilitating desiccation tolerance are metabolic “switch-off” and intracellular dedifferentiation. Recalcitrant seeds lack these mechanisms, contributing significantly to their desiccation sensitivity. Consequently, recalcitrant seeds, which are shed at high water contents, can be stored only in the short-term, under conditions not allowing dehydration. The periods of such hydrated storage are constrained by germination that occurs without the need for extraneous water, and the proliferation of seed-associated fungi. Cryopreservation is viewed as the only option for long-term conservation of the germplasm of recalcitrant-seeded species. This is not easily achieved, as each of the necessary procedures imposes oxidative damage. Intact recalcitrant seeds cannot be cryopreserved, the common practice being to use excised embryos or embryonic axes as explants. Dehydration is a necessary procedure prior to exposure to cryogenic temperatures, but this is associated with metabolism-linked injury mediated by uncontrolled reactive oxygen species generation and failing anti-oxidant systems. While the extent to which this occurs can be curtailed by maximizing drying rate (flash drying) it cannot be completely obviated. Explant cooling for, and rewarming after, cryostorage must necessarily be rapid, to avoid ice crystallization. The ramifications of desiccation sensitivity are discussed, as are problems involved in cryostorage, particularly those accompanying dehydration and damage consequent upon ice crystallization. While desiccation sensitivity is a “fact” of seed recalcitrance, resolutions of the difficulties involved germplasm conservation are possible as discussed.

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“…Of all these P-values, only the Lima bean gene pool from 1979 had values close to a = 0.05. It is important to remember that the accessions of Nohalal-1979 were obtained from the CIAT seed bank where the preservation process of the seed can lead to genetic erosion (Gómez-Campo 2006;Parzies et al 2000). Even with this, Nohalal-1979 gene pool had higher genetic diversity than the all-2007 gene pool (H = 0.18 vs. H = 0.05, respectively).…”

Section: Bottleneck Analysismentioning

confidence: 99%

“…An important aspect in studies of genetic erosion in crops is sampling strategy (Gómez-Campo 2006;Guerrant 1992;Parzies et al 2000;Sherwin and Moritz 2000). Even though the seed samples for the 2 years of collection in this study differed (seed origin, sample size), we consider that the results obtained for allelic composition, genetic diversity estimators, AMOVA, and cluster analysis are consistent: a great proportion of the genetic diversity present in 1979 has been lost; however, this loss cannot be explained by the existence of recent bottleneck events.…”

Section: Implications For Conservationmentioning

confidence: 99%

“…Seed banks, preserving large amounts of genetic material in a small space, are the most practical source. But paradoxically, seed banking practices can induce high levels of internal genetic erosion, starting with the sampling process and continuing through the rest of the processes such as initial or periodic germination tests, distribution, and regeneration (Gómez-Campo 2006;Parzies et al 2000).…”

Section: Introductionmentioning

confidence: 99%

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Wholesale replacement of lima bean (Phaseolus lunatus L.) landraces over the last 30 years in northeastern Campeche, Mexico

Martínez-Castillo

Camacho-Pérez

Coello-Coello

et al. 2011

Genet Resour Crop Evol

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Genetic erosion has been evaluated at the landrace level in the past, principally because the loss of landraces is believed to generate erosion at the allelic level; however, few studies had tested this hypothesis in the crop's centers of diversity and domestication. Using microsatellite markers, we analyzed for genetic erosion in lima bean (Phaseolus lunatus) landraces over time in samples collected in 1979 and in 2007 in northeast Campeche, in the Yucatan peninsula, Mexico, an important diversity center and part of the putative domestication area for this crop. We found that the lima bean genetic pool from 1979 had a higher genetic diversity than the one for the 2007 pool (Nei's diversity, H = 0.18 and 0.05, respectively). Although this result could not to be explained using a bottleneck analysis, a cluster analysis showed that the alleles present in 1979 were not the same as those found in 2007, indicating an allelic displacement in the genetic pool of the lima bean landraces in the last 30 years. This displacement could be due to the introduction of improved varieties or landraces, resulting in a displacement of local varieties or to changes in the Mayan criteria for selection of germplasm or both. This study showed that the loss of landraces can generate both quantitative and qualitative changes in the genetic pool of the domesticated species. Such changes are very important to consider when planning ex situ and in situ programs to conserve crop diversity in their domestication areas.

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Erosion of genetic resources within seed genebanks: the role of seed containers

Cited by 23 publications

References 3 publications

Genetic structure of Lima bean (Phaseolus lunatus L.) landraces grown in the Mayan area

Genetic structure of Lima bean (Phaseolus lunatus L.) landraces grown in the Mayan area

Implications of the lack of desiccation tolerance in recalcitrant seeds

Wholesale replacement of lima bean (Phaseolus lunatus L.) landraces over the last 30 years in northeastern Campeche, Mexico

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