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

Stable isotope natural abundances (δ13C and δ15N) and carbon-water relations as drought stress mechanism response of taro (Colocasia esculenta L. Schott)

Taro (Colocasia esculenta L. Schott) is an important staple food crop in tropical and developing countries, having high water requirements. The purpose of this study was to evaluate the feasibility of using carbon and nitrogen isotopic composition (δ13C and δ15N) as a physiological indicator of taro response to drought, and elucidation of the relationship between the water use efficiency (WUE) under drought conditions and carbon isotope discrimination (Δ13C). As an alternative to WUE determination, obtained by measuring plant growth and water loss during an entire vegetative cycle, we have used Δ13C to determine the tolerance of C3 taro plants to drought. Seven taro accessions from Madeira, Canary Islands and the Secretariat of the Pacific Community (Fiji) collections were grown under greenhouse conditions and subjected to different watering regimes during a one-year cycle. Total plant biomass (TPB), WUE and δ15N were determined at the whole-plant level (WP). Corms and shoots were evaluated separately for nitrogen content (N), δ13C, Δ13C and δ15N. WUE showed positive correlation with TPB (r = 0.4) and negative with Δ13C (r = -0.3); Corm δ15N showed positive correlations with WP δ15N (r = 0.6) and corm N (r = 0.3). Accordingly, the taro plants with enhanced WUE exhibited low Δ13C and δ15N values as a physiological response to drought stress. The approach used in the present study has developed new tools that could be used in further research on taro response to environmental stresses.This work was supported by the Programa Operacional da Região Autónoma da Madeira – PO Madeira 14–20 [grant number M1420-01- 0145-FEDER-000011, CASBio] and the Agência Regional para o Desenvolvimento da Investigação Tecnologia e Inovação – ARDITI [grant number M1420-09-5369-FSE-000001].info:eu-repo/semantics/publishedVersio

Nutritional and mineral variability in 52 accessions of common bean varieties (Phaseolus vulgaris L.) from Madeira Island

The Phaseolus vulgaris L. is one of the traditional and most important leguminous crops in the Island of Madeira. The island’s bioclimatic tiers, agro-ecological environment and traditional farming practices had a great influence on the evolution of regional bean landraces. The variabili ty of the nutritional and mineral seeds composition of 59 accessions of the Madeiran landraces, standard and commercial varieties was evaluated. Wide ranges of variability in biochemical pa rameters were reported among the Madeiran landraces, being the best sources of protein and mineral nutrition, according to the statistical results and literature comparative evaluation. Spe cifically, the content (g per 100 g DW) of ash ranged from 3.64 - 5.67, lipids from 0.57 - 2.86, pro tein from 18.55 - 29.69, starch from 23.40 - 52.65, soluble sugars from 2.97 - 6.84, while content of dry matter was from 83.35 - 93.55. The seeds also contained (per 100 g DW) between 2.55 - 4.83 g N, 0.30 - 7.50 g P, 1.30 - 2.49 g K, 0.10 - 0.18 g Mg, 4.10 - 10.00 mg Fe, 50.0 - 1.40 mg Cu, 2.20 - 5.00 mg Zn, 0.90 - 3.80 µg Mn and 0.20 - 2.40 µg B. This variability implies that the screened germplasm could serve as a source for breeding new varieties with improved biochemical and nutritional traits or could be highly recommended to meet specific dietary requirements. The cultivar Vagin ha Grossa (ISOP 713) revealed low carbohydrate content that could be a good food choice for di abetics, while cultivar Vermelho (ISOP 724) bean should be offered as a valuable alternative source of protein and minerals in the local diet.info:eu-repo/semantics/publishedVersio

Ecology and diversity of Solanum trisectum Dunal from Madeira Island: implications for Its conservation

Solanum trisectum Dunal is an endemic Solanaceae of Madeira Island (Portugal), considered critically endangered due to its extreme rarity. Since its discovery this species has shown a narrow distributional range mainly on the northern side of the island, with scattered and small populations and large time gaps between sightings. The present work aimed to understand the underlying ecological underpinnings for this species rarity towards an effort to increase the success of conservation actions. Data on historical locations, environmental conditions field surveys, reinforcement in situ and ex situ germination trials were obtained. The species was found to currently occur only in two wild populations and two reinforcement sites, amounting to twenty-four plants in total. Statistical analysis of these data related wild populations and successful reinforcement sites, separating them from other sites where the reinforcement did not succeed. This suggests that the successful reinforcement sites showed conditions more similar to wild population sites compared to non-successful ones. The data obtained supports the hypothesis that S. trisectum distribution and rarity is determined by species specific habitat needs, i.e., abiotic conditions, which have been for the first time assessed during the present work. Further, this study also reinforces the classification of S. trisectum as a top priority species for conservation.Prospecting, Monitoring and Conservation of Normania triphylla in Madeira (Mohamed bin Zayed Species (project number 13255498)) and Madeira PO 14-20, contract CASBIO (ref M1420-01- 0145-FEDER-000011 ).info:eu-repo/semantics/publishedVersio

Screening for Drought Tolerance in Thirty Three Taro Cultivars

Taro [Colocasia esculenta (L.) Schott] is a root crop which is an important staple food in many regions of the world, producing 10.5 million tonnes on 1.4 million hectares a year. The crop is cultivated in wet (rain fed) or irrigated conditions, requiring on average 2,500 mm water per year, and in many countries it is cultivated in flooded plots. It is estimated that taro production could decrease by 40% as a result of the increase in drought and other severe events. In this work, thirty three accessions, including local cultivars, selected and hybrid lines were submitted to long duration drought stress and screened for tolerance. Twelve physiological, morphological and agronomic traits were measured at harvest, and subject to multivariate analysis. Stress indices, Water Use Efficiency and Factorial Analysis were useful for discriminating accessions regarding drought tolerance and yield stability, and drought tolerant and susceptible cultivars were identified. Our results confirm that different taro cultivars have different drought avoidance and tolerance strategies to cope with water scarcity. Better yield performers minimised biomass and canopy loss, while tolerance was observed in cultivars that presented low potential yield, but efficiently transferred resources to enhance corm formation. Among the 33 accessions, two local cultivars showed high yield stability and could be considered as suitable parents for breeding programs, while two others are well adapted to drought, but with overall low yield potential

Phenotyping the ideotypes of two maize landraces from Madeira archipelago using morpho-agronomic traits and zein pattern

Madeira Archipelago holds specific maize genetic resources whose populations, representing field diversity, were previously classified into four main landrace groups. The ISOPs 0061 and 0070, with common names of “Milho Sequeiro” and “Milho Branco” yellow and white maize, respectively, represent the ideotypes of two of these landraces. These ideotypes have now been analyzed using morpho-agronomic and biochemical traits, to phenotype these landraces. The variation of nine of the ten morpho-agronomic traits was used to separate the landraces ideotypes. However, the seven traits of seed biochemical composition did not allow to segregate the landraces ideotypes. This is not the case of zein pattern, which polymorphism shows to be specific for each ideotype. The original ideotypes populations were regenerated twice under low input conditions. Zein patterns of the original and regenerated accessions were compared, using two electrophoresis techniques. The lab-on-a-chip electrophoresis showed that the standard SDS-PAGE zein pattern with six fractions could be separated into eighteen (ISOP 0061) and twenty (ISOP 0070) protein bands. In contrast, no significant changes were detected in the zein pattern structure of the initial and regenerated accessions of both landraces ideotypes. The chip electrophoresis showed to be a suitable technique to screen and characterize a large number of individuals and accessions of the germplasm collections, due to its reproducibility. In particular, the zein patterns can be used to phenotype ideotypes and establish a formula representing their structure, allowing to detect changes in landrace structure, occurring as a result of gene bank management actions.info:eu-repo/semantics/publishedVersio

Quantitation of oxalates in corms and shoots of Colocasia esculenta (L.) Schott under drought conditions

Oxalate (calcium oxalate) accumulation in taro plants (Colocasia esculenta (L.) Schott) impacts their nutritional quality, producing acridity, causing lips, mouth and throat tissues swelling if consumed fresh. The oxalate content is related to photosynthesis, through the glycolate–glyoxylate oxidation pathway. The plant's photosynthetic rate usually increases in non-stressed conditions. Differences in photosynthetic rate are indirectly related to the chlorophyll content index. Protein accumulation and starch variation are also important traits to understand the taro oxalate synthesis caused by drought and how they affect corm quality. The purpose of this study was to quantitate oxalates in taro corms and shoots submitted to drought conditions and to evaluate how stress response can affect the nutritional quality of taro whole-plant. Seven taro genotypes from Madeira, Canaries and Pacific Community (SPC) collections were grown in greenhouse conditions and submitted to different watering regimes for drought tolerance screening. Corms and shoots were harvested and evaluated for oxalates (soluble, insoluble and total), chlorophyll content index (CCI), crude protein, starch, starch solubility in water and starch swelling power. All accessions had very high calcium oxalate content. Drought-tolerant genotypes showed good osmotic response by oxalate precipitation and mobilization through shoot to corm tissues, photosynthesis adaptation by increase of CCI, protein accumulation, and very low starch hydrolysis. Sensitive-drought genotypes showed less mobilization of calcium oxalate, decreased photosynthetic rate and protein synthesis, and slight increase of starch hydrolysis. Variation in taro oxalate content is consistent and significantly correlated with the photosynthetic rate, carbohydrate metabolism and protein synthesis

Variation of carbon and isotope natural abundances (δ15N and δ13C) of whole-plant sweet potato (Ipomoea batatas L.) subjected to prolonged water stress

Sweet potato (Ipomoea batatas L.) is an important crop in the world, cultivated in temperate climates under low inputs. Drought changes the plant biomass allocation, together with the carbon and nitrogen isotopic composition (δ13C and δ15N), whose changes are faintly known in sweet potato crops. Here, we show the biomass allocation of eight sweet potato accessions submitted to drought during 3 months, using the δ13C, δ15N, carbon isotope discrimination (Δ13C), total carbon (TC) and water use efficiency (WUE) traits. The tolerant accessions had improved WUE, with higher TPB and TC. Storage roots and shoots had a heavier δ13C content under drought stress, with greater 13C fixation in roots. The Δ13C did not show a significant association with WUE. The δ15N values indicated a generalised N reallocation between whole-plant organs under drought, as a physiological integrator of response to environmental stress. This information can aid the selection of traits to be used in sweet potato breeding programs, to adapt this crop to climate change

Prospeção e caracterização dos recursos genéticos de macieira, Malus domestica Borkh, na Madeira

A Madeira possui condições agroecológicas únicas, que permitem o desenvolvimento de grande diversidade de espécies frutícolas. A macieira é uma fruteira tradicional na Madeira que se distribui pelas suas freguesias montanhosas, desde o Oeste, Achadas da Cruz, até o Este, Faial. O cultivo da macieira desenvolve-se em pequenos pomares, que albergam uma diversidade de cultivares, cuja produção é consumida em fresco ou utilizada na produção de sidra. A prospeção e inventariação dos recursos genéticos desta fruteira procura aprofundar os conhecimentos sobre a sua diversidade, tendo resultado no registo de 10 variedades de conservação no Catálogo Nacional de Variedades, entre as quais o Pero Domingos, a Maçã Barral, a Maçã Cara de Dama e o Pero Calhau. Os dados desta inventariação são disponibilizados, através das plataformas GRIN-Global e GBIF. Está em curso um projeto que visa a valorização destas variedades locais, através da sua caracterização morfo-agronómica e nutricional. O presente trabalho apresenta os resultados preliminares da caracterização morfométrica de 4 dessas variedades. Os parâmetros utilizados incluem o hábito de crescimento, época de floração, frutificação e colheita, e 10 caracteres morfológicos do fruto. Os resultados obtidos permitem-nos inferir que as 4 variedades são distintas entre si e apresentam características agronómicas que lhes conferem valor comercial. Adicionalmente, o fruto do Pero Domingos foi analisado em relação a 5 parâmetros nutricionais e físico-químicos, e à sua aptidão para consumo em fresco ou processado (desidratado, compotas, sidra). O Pero Domingos apresentou um bom tempo de conservação no pós-colheita. No entanto, recomenda-se o seu uso na produção de sidra ou confeção de compotas até 1 semana de pós-colheita. O teor de sólidos solúveis variou significativamente nas compotas. O pH da sidra diminuiu significativamente com a profundidade da coluna na pipa.Madeira has ideal agroecological conditions, allowing the development of a great diversity of fruits. The apple tree is a traditional fruit tree of Madeira, distributed in the mountainous parishes of Madeira, between West (Achadas da Cruz) and the East (Faial) of the island. The cultivation of the apple tree takes place in small orchards that shelter a high diversity of local cultivars whose production is used for fresh consumption or cider production. Since 2006, the survey of these genetic resources has sought to deepen the knowledge about the diversity of the apple tree, having resulted in the registration of 10 landraces in the National Catalog of Varieties, among them Pero Domingos, Maçã Barral, Maçã Cara de Dama and Pero Calhau. The results of this survey was available, through the GRIN-Global and GBIF platforms. A project is currently undertaken to perform the morph-agronomic and nutritional characterization of these varieties. The goal of the present work is to show the data of the characterization of these 4 varieties, using characters linked with the growth habit, flowering, fruiting and harvest season, and 10 morphological fruit characters. It was observed that these varieties are distinct and have agronomic features that give them a commercial value. At same time, Pero Domingos fruits were analyzed using 5 nutritional and physical-chemical parameters, as well as its aptitude for fresh or processed consumption (dehydrated fruits, jam, cider). Fruits shown good post-harvest durability. However, best apples for cider or jams should be harvested for less than a week. Soluble solids content varied significantly in the processed apple, with a gradual increase in jam, jelly and marmalade. The pH of the cider decreased significantly with the depth of storage column in the cask.info:eu-repo/semantics/publishedVersio