203 research outputs found
Adapting clonally propagated crops to climatic changes: a global approach for taro (Colocasia esculenta (L.) Schott)
Clonally propagated crop species are less
adaptable to environmental changes than those propagating
sexually. DNA studies have shown that in all
countries where taro (Colocasia esculenta (L.) Schott)
has been introduced clonally its genetic base is
narrow. As genetic variation is the most important
source of adaptive potential, it appears interesting to
attempt to increase genetic and phenotypic diversity to
strengthen smallholders’ capacity to adapt to climatic
changes. A global experiment, involving 14 countries
from America, Africa, Asia and the Pacific was
conducted to test this approach. Every country
received a set of 50 indexed genotypes in vitro
assembling significant genetic diversity. After onstation
agronomic evaluation trials, the best genotypes
were distributed to farmers for participatory on-farm
evaluation. Results indicated that hybrids tolerant to
taro leaf blight (TLB, Phytophthora colocasiae Raciborski),
developed by Hawaii, Papua New Guinea and
Samoa breeding programmes outperformed local cultivars in most locations. However, several elite
cultivars from SE Asia, also tolerant to TLB, outperformed
improved hybrids in four countries and in one
country none of the introductions performed better
than the local cultivars. Introduced genotypes were
successfully crossed (controlled crossing) with local
cultivars and new hybrids were produced. For the first
time in the history of Aroids research, seeds were
exchanged internationally injecting tremendous allelic
diversity in different countries. If climatic changes are
going to cause the problems envisaged, then breeding
crops with wide genetic diversity appears to be an
appropriate approach to overcome the disasters that
will otherwise ensue.This research was financially supported
by the Europe-Aid project ‘‘Adapting clonally propagated crops
to climatic and commercial changes’’ (Grant No. DCI-FOOD/
2010/230-267 SPC). Thanks are due to the 14 different countries
technicians working on research stations and to farmers and
their families for their enthusiastic contributioninfo:eu-repo/semantics/publishedVersio
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Sequencing wild and cultivated cassava and related species reveals extensive interspecific hybridization and genetic diversity
Cassava (Manihot esculenta) provides calories and nutrition for more than half a billion people. It was domesticated by native Amazonian peoples through cultivation of the wild progenitor M. esculenta ssp. flabellifolia and is now grown in tropical regions worldwide. Here we provide a high-quality genome assembly for cassava with improved contiguity, linkage, and completeness; almost 97% of genes are anchored to chromosomes. We find that paleotetraploidy in cassava is shared with the related rubber tree Hevea, providing a resource for comparative studies. We also sequence a global collection of 58 Manihot accessions, including cultivated and wild cassava accessions and related species such as Ceará or India rubber (M. glaziovii), and genotype 268 African cassava varieties. We find widespread interspecific admixture, and detect the genetic signature of past cassava breeding programs. As a clonally propagated crop, cassava is especially vulnerable to pathogens and abiotic stresses. This genomic resource will inform future genome-enabled breeding efforts to improve this staple crop
Ipomoea batatas (L.) Lam.: a rich source of lipophilic phytochemicals
The lipophilic extracts from the storage root of 13 cultivars of sweet potato (Ipomoea batatas (L.) Lam.) were evaluated by gas chromatography-mass spectrometry with the aim to valorize them and offer information on their nutritional properties and potential health benefits. The amount of lipophilic extractives ranged from 0.87 to 1.32% dry weight. Fatty acids and sterols were the major families of compounds identified. The most abundant saturated and unsaturated fatty acids were hexadecanoic acid (182-428 mg/kg) and octadeca-9,12-dienoic acid (133-554 mg/kg), respectively. β-Sitosterol was the principal phytosterol, representing 55.2-77.6% of this family, followed by campesterol. Long-chain aliphatic alcohols and α-tocopherol were also detected but in smaller amounts. The results suggest that sweet potato should be considered as an important dietary source of lipophilic phytochemicals.info:eu-repo/semantics/publishedVersio
Genetic structure and differentiation in cultivated fig (Ficus carica L.)
One hundred ninety-four germplasm accessions of fig representing the four fig types, Common, Smyrna, San Pedro, and Caprifig were analyzed for genetic diversity, structure, and differentiation using genetic polymorphism at 15 microsatellite loci. The collection showed considerable polymorphism with observed number of alleles per locus ranging from four for five different loci, MFC4, LMFC14, LMFC22, LMFC31 and LMFC35 to nine for LMFC30 with an average of 4.9 alleles per locus. Seven of the 15 loci included in the genetic structure analyses exhibited significant deviation from panmixia, of which two showed excess and five showed deficiency of heterozygote. The cluster analysis (CA) revealed ten groups with 32 instances of synonymy among cultivars and groups differed significantly for frequency and composition of alleles for different loci. The principal components analysis (PCA) confirmed the results of CA with some groups more differentiated than the others. Further, the model based Bayesian approach clustering suggested a subtle population structure with mixed ancestry for most figs. The gene diversity analysis indicated that much of the total variation is found within groups (HG/HT = 0.853; 85.3%) and the among groups within total component (GGT = 0.147) accounted for the remaining 14.7%, of which ~64% accounted for among groups within clusters (GGC = 0.094) and ~36% among clusters (GCT = 0.053). The analysis of molecular variance (AMOVA) showed approximately similar results with nearly 87% of variation within groups and ~10% among groups within clusters, and ~3% among clusters. Overall, the gene pool of cultivated fig analyzed possesses substantial genetic polymorphism but exhibits narrow differentiation. It is evident that fig accessions from Turkmenistan are somewhat genetically different from the rest of the Mediterranean and the Caucasus figs. The long history of domestication and cultivation with widespread dispersal of cultivars with many synonyms has resulted in a great deal of confusion in the identification and classification of cultivars in fig
Kava and ethno-cultural identity in Oceania
Garibaldi and Turner (Ecol Soc 9:1, 5, 2004) explain the role that particular plants play in facilitating the shared ancestry, practices, and social experience of an ethnicity. This can include spiritual connections, cultural expression and practice, ceremony, exchange, linguistic reflection, socialization, and medicinal and/or dietary systems. They term these plants “cultural keystone species” and icons of identity, plants that if removed would cause some disruptions to the cultural practices and identity of an ethnic group. Undoubtedly, kava (Piper methysticum) is the cultural keystone species for many Oceanic and Pacific peoples, a “differentiating element of common culture” (Zagefka, Ethnicity, concepts of. In: Smith AD, Hou X, Stone J, Dennis R, Rizova P (eds) The Wiley Blackwell encyclopedia of race, ethnicity, and nationalism. West Wiley, Sussex, pp 761–763, 2016) informing their ethno-cultural identity. That influence is also extending to new non-Pacific Island user groups who have embraced elements of kava ethno-cultural identity in what has been termed diasporic identity formation in reverse. This chapter will discuss kava with specific reference to ethnic positionality in Fiji while recognizing the tensions from inside and outside the region that support and threaten the continuance of the kava drinking tradition
Development and characterization of polymorphic microsatellite markers in taro (Colocasia esculenta)
Microsatellite-containing sequences were isolated from enriched genomic libraries of taro (Colocasia esculenta (L.) Schott). The sequencing of 269 clones yielded 77 inserts containing repeat motifs. The majority of these (81.7%) were dinucleotide or trinucleotide repeats. The GT/CA repeat motif was the most common, accounting for 42% of all repeat types. From a total of 43 primer pairs designed, 41 produced markers within the expected size range. Sixteen (39%) were polymorphic when screened against a restricted set of taro genotypes from Southeast Asia and Oceania, with an average of 3.2 alleles detected on each locus. These markers represent a useful resource for taro germplasm management, genome mapping, and marker-assisted selection
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