175 research outputs found
Changes in oxalate composition and other nutritive traits in root tubers and shoots of sweet potato (Ipomoea batatasL. [Lam.]) under water stress
BACKGROUND: The presence of insoluble calcium oxalate druse crystals (CaOx) in sweet potato (Ipomoea batatas) can negatively
affect its nutritional quality. Photosynthesis, starch, and protein composition are linked with oxalate synthesis and tuber quality
under water scarcity. Our main objective was the oxalate quantitation of sweet potato tubers and shoots and also to assess
how drought changes their nutritional value. Eight sweet potato accessions from Madeira, the Canaries and Guinea-Bissau were
analyzed for their response to drought stress. Tubers and shoots were analyzed for total (T-Ox), soluble (S-Ox) and insoluble
(CaOx) oxalates, protein, chlorophyll content index (CCI), soluble starch, starch swelling power, and starch solubility in water.
RESULTS: The S-Ox and CaOx content was higher in shoots. Six accessions were above maximum CaOx levels for raw consumption. Accessions with more favorable responses to drought had decreased CaOx with S-Ox increase content for osmoregulation.
They also presented slightly decreased CCI and protein contents. These accessions also had an increased shoot starch content,
for further tuber storage starch hydrolysis, and maintained the quality and functional properties of the tuber starch grain. Those
with a less favorable response to drought had a higher T-Ox and CaOx content in both organs, hindering water absorption. They
also had decreased protein and CCI, with a slight increase in tuber starch hydrolysis.
CONCLUSION: Oxalate content was significantly related to carbohydrate metabolism, CCI, and protein synthesis. This study
significantly contributed to the screening of the sweet potato stress response to drought, to adapt this crop to climatic change
through breeding programs.info:eu-repo/semantics/publishedVersio
Drought avoidance and phenotypic flexibility of sweet potato (Ipomoea batatas (L.) Lam.) under water scarcity conditions
Sweet potato (Ipomoea batatas (L.) Lam.) is an important staple food in several regions of the world. Water scarcity is the
most devastating abiotic stress, with a great impact on crop productivity, food security, and subsistence. Drought restricts the
nutrient intake and transport into the plant. Tolerant crops have morphological mechanisms of drought avoidance and/or
phenotypic flexibility, showing also good water and nutrient efficiency. However, that information is scarce for sweet potato,
which is usually based on physiological traits of plant productivity. Here, we show the physiological responses of eight sweet
potato accessions subjected to a 3 months’ drought period, by recording their differences for nutrient and leaf chlorophyll
content, biomass and stress level. Our results showed that the differences in water use efficiency (WUE, +68.1%), chlorophyll
content index (CCI, -5.3%), total plant biomass (TPB, -55.4%), nutrient efficiency (NER, +38.1%) and nutrient harvest index
(NHI, +2.9%) where significantly correlated with the water regime. The water shortage led to a drought avoidance response,
with TPB loss in all accessions. Distinct phenotypic flexibility responses were also recorded and explained by the root:shoot
ratio (R:S) and stress index (SI) variation of the storage root and shoot growth. This information could be relevant for the
development of sweet potato breeding programs, adapting this crop to climate change.info:eu-repo/semantics/publishedVersio
Phenotypic flexibility and drought avoidance in taro (Colocasia esculenta (L.) Schott)
Taro (Colocasia esculenta (L.) Schott) is a substantial staple food in most of the tropical regions. Prolonged exposure to drought impairs crop production worldwide. Tolerant crops have the best capability to cope and avoid drought, through phenotypic flexibility mechanisms. The water use efficiency (WUE) is well known in taro crops, but very scarce information is available relating to their nutrient efficiency (NER) in drought conditions. Our work provided pertinent information about the physiological variation of seven taro accessions subjected to seven months of drought, by recording the differences for nutrient allocation, chlorophyll canopy, biomass loss, and stress intensity. Significant relationships between control and drought treatments on WUE (+85%), total plant biomass (TPB, -26.8%), chlorophyll content index (CCI, +1.8%), and nutrient harvest index (NHI, +0.2%) were detected. Drought led to a generalized loss of TPB as drought avoidance strategy, although distinct phenotypic flexibility was observed through the root: shoot ratio (R:S) and stress index (SI) from the corm and shoot organs. The nutrient allocation from the corms to shoots, with NER increase registered in drought conditions, can be a valuable tool to complement the TPB and WUE productivity traits, to be used in taro breeding programs.info:eu-repo/semantics/publishedVersio
Drought Avoidance and Phenotypic Flexibility of Sweet Potato (Ipomoea batatas (L.) Lam.) Under Water Scarcity Conditions
Sweet potato (Ipomoea batatas (L.) Lam.) is an important staple food in several regions of the world. Water scarcity is the most devastating abiotic stress, with a great impact on crop productivity, food security, and subsistence. Drought restricts the nutrient intake and transport into the plant. Tolerant crops have morphological mechanisms of drought avoidance and/or phenotypic flexibility, showing also good water and nutrient efficiency. However, that information is scarce for sweet potato, which is usually based on physiological traits of plant productivity. Here, we show the physiological responses of eight sweet potato accessions subjected to a 3 months’ drought period, by recording their differences for nutrient and leaf chlorophyll content, biomass and stress level. Our results showed that the differences in water use efficiency (WUE, +68.1%), chlorophyll content index (CCI, -5.3%), total plant biomass (TPB, -55.4%), nutrient efficiency (NER, +38.1%) and nutrient harvest index (NHI, +2.9%) where significantly correlated with the water regime. The water shortage led to a drought avoidance response, with TPB loss in all accessions. Distinct phenotypic flexibility responses were also recorded and explained by the root:shoot ratio (R:S) and stress index (SI) variation of the storage root and shoot growth. This information could be relevant for the development of sweet potato breeding programs, adapting this crop to climate change
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
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
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