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1.
Physiol Plant ; 176(5): e14525, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-39317989

RESUMO

Physiological seed drop is a recognized phenomenon in economic forest, caused by the abscission of developing seeds due to intergroup competition for resources. However, little is known about the resource allocation dynamics in species exhibiting a biennial fruiting cycle, where interactions occur not only among seeds of the same year but also between reproductive structures from consecutive years. In this study, we explored the dynamics of resource allocation in Torreya grandis, a nut crop with a prototypical two-year seed development pattern. We implemented thinning treatments of 0%, 30%, and 60% on female cones and/or immature seeds during the spring, targeting various stages of development both pre- and post-pollination. Our findings reveal a pronounced resource competition in Torreya, evidenced by a natural seed-setting rate of merely 9.4%. Contrary to expectations, seed thinning did not lead to an obvious increase in nut-setting rates, whereas a substantial increase to 20.5% was observed when female cones were thinned by 60% at 20 days before pollination. The cone thinning treatment appears to have influenced seed development through positive cytokinin and negative abscisic acid effects. This indicates that intergroup competition between female cones and nuts is a more significant factor in seed drop than inner nut competition, and there seems to be an interaction between the two groups. We demonstrate that, in Torreya with biennial seed development, it is the competition between female cones and immature seeds that is important. This insight expands our comprehension of the physiological mechanisms governing seed drop in biennial fruiting species and managing the reproductive organ load to optimize nutrient allocation.


Assuntos
Nozes , Sementes , Sementes/fisiologia , Sementes/crescimento & desenvolvimento , Nozes/fisiologia , Polinização/fisiologia , Estações do Ano , Nutrientes/metabolismo , Ácido Abscísico/metabolismo , Citocininas/metabolismo
2.
PLoS One ; 16(5): e0250293, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33939737

RESUMO

The scarcity of information on the maturation physiology of the peanut seed (Arachis hypogaea L.; Virgínia group) makes harvesting high quality seeds a challenge for the seed industry. During two consecutive crop seasons, we studied the acquisition of physiological quality of peanut seeds during maturation in tropical conditions. We bring new insights about the period of late maturation of seeds and the influence of the maternal environment on physiological quality. We monitored water content, dry weight, ability of germination, desiccation tolerance, vigor and longevity. In addition, we monitored temperature and precipitation throughout plant growth. We demonstrate that the physiological quality of peanut seeds is acquired during development, with a maximum between 57 and 76 days after flowering in the late stage of maturation. This final period represents about 25% of the development, considered the best time to harvest peanut seeds with the highest quality. Our findings also support the idea that the adequate proportion of rainfall and thermal sum in the maternal environment are factors that favor the acquisition of peanut seed longevity.


Assuntos
Arachis/crescimento & desenvolvimento , Produção Agrícola/métodos , Nozes/normas , Aclimatação , Arachis/fisiologia , Meio Ambiente , Germinação , Nozes/crescimento & desenvolvimento , Nozes/fisiologia , Pressão Osmótica
3.
Sci Rep ; 11(1): 4568, 2021 02 25.
Artigo em Inglês | MEDLINE | ID: mdl-33633151

RESUMO

Climate change and population increase are two challenges for crop production in the world. Hazelnut (Corylus avellana L.) is considered an important nut regarding its nutritional and economic values. As a fact, the application of supporting materials as foliage sprays on plants will decrease biotic and abiotic stresses. In this study, the effects of salicylic acid (0, 1 mM and 2.5 mM) and kaolin (0, 3% and 6%) sprays were investigated on morphological, physiological, pomological, and biochemical characteristics of hazelnut. The results showed that 1 mM salicylic acid and 6% kaolin had the best effects on nut and kernel weight compared to control. Biochemical parameters such as chlorophyll a, b, a + b, and carotenoid contents showed that salicylic acid and kaolin improved pigment concentration. Proline and antioxidant contents such as phenolic acids, SOD, APX, and CAT enzyme activities increased by these applications. On the other hand, lipid peroxidation, protein content, and H2O2 content were decreased. Based on the tolerance index result, Merveille de Bollwiller cultivar showed the highest tolerance while 'Fertile de Coutard' had the lowest value. Therefore, hazelnut performance may be improved through exogenous application of the signaling (salicylic acid) and particle film (Kaolin) compounds in warmer climates.


Assuntos
Corylus/efeitos dos fármacos , Corylus/fisiologia , Caulim/farmacologia , Nozes/efeitos dos fármacos , Nozes/fisiologia , Ácido Salicílico/farmacologia , Antioxidantes/metabolismo , Corylus/química , Eletrólitos , Regulação Enzimológica da Expressão Gênica , Nozes/química , Especificidade de Órgãos , Oxirredução , Compostos Fitoquímicos , Característica Quantitativa Herdável , Temperatura
4.
Diabetes Care ; 43(2): 265-271, 2020 02.
Artigo em Inglês | MEDLINE | ID: mdl-31959642

RESUMO

Prevailing dietary guidelines have widely recommended diets relatively low in red and processed meats and high in minimally processed plant foods for the prevention of chronic diseases. However, an ad hoc research group called the Nutritional Recommendations (NutriRECS) consortium recently issued "new dietary guidelines" encouraging individuals to continue their current meat consumption habits due to "low certainty" of the evidence, difficulty of altering meat eaters' habits and preferences, and the lack of need to consider environmental impacts of red meat consumption. These recommendations are not justified, in large part because of the flawed methodologies used to review and grade nutritional evidence. The evidence evaluation was largely based on the Grading of Recommendations, Assessment, Development, and Evaluation (GRADE) criteria, which are primarily designed to grade the strength of evidence for clinical interventions especially pharmacotherapy. However, the infeasibility for conducting large, long-term randomized clinical trials on most dietary, lifestyle, and environmental exposures makes the criteria inappropriate in these areas. A separate research group proposed a modified and validated system for rating the meta-evidence on nutritional studies (NutriGRADE) to address several limitations of the GRADE criteria. Applying NutriGRADE, the evidence on the positive association between red and processed meats and type 2 diabetes was rated to be of "high quality," while the evidence on the association between red and processed meats and mortality was rated to be of "moderate quality." Another important limitation is that inadequate attention was paid to what might be replacing red meat, be it plant-based proteins, refined carbohydrates, or other foods. In summary, the red/processed meat recommendations by NutriRECS suffer from important methodological limitations and involve misinterpretations of nutritional evidence. To improve human and planetary health, dietary guidelines should continue to emphasize dietary patterns low in red and processed meats and high in minimally processed plant foods such as fruits and vegetables, whole grains, nuts, and legumes.


Assuntos
Diabetes Mellitus Tipo 2/etiologia , Dieta/efeitos adversos , Comportamento Alimentar/fisiologia , Carne/efeitos adversos , Carne Vermelha/efeitos adversos , Diabetes Mellitus Tipo 2/epidemiologia , Dieta/estatística & dados numéricos , Projetos de Pesquisa Epidemiológica , Manipulação de Alimentos/estatística & dados numéricos , Preferências Alimentares/fisiologia , Frutas/fisiologia , Humanos , Nozes/fisiologia , Estudos Observacionais como Assunto/normas , Estudos Observacionais como Assunto/estatística & dados numéricos , Fatores de Risco , Verduras/fisiologia , Grãos Integrais/fisiologia
5.
J Plant Physiol ; 240: 153013, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31374485

RESUMO

The HCN-induced seed dormancy release necessitates alterations in reactive oxygen species (ROS) metabolism and radicle cell wall loosening. Little is known about the interaction of ROS metabolism with cell wall hydrolytic enzymes during HCN-induced seed dormancy release. Thus dormant walnut (Juglans regia L.) kernels were exposed to HCN (4 h) and studied for redox metabolism and cell wall-modifying enzymes during 10 days of incubation (DI) i.e. before radicle emergence. HCN increased ROS especially in the embryonic axes (EAs) but decreased ROS-generating NADPH oxidase and ROS scavenging superoxide dismutase (SOD) and peroxidase (POX) with no effects on catalase (CAT), ascorbate peroxidase (APX) and cell wall-modifying enzymes activities in short term up to 2 DI. In long term roughly from 4 DI onwards, HCN-exposed EA displayed greater superoxide anions and enhanced activities of POX, APX, NADPH oxidase, cell wall peroxidase (CW-POX), ß- 1, 4-D glucanase, mannanase, polygacturonase and xylanase. Meanwhile HCN increased greater expression of POX and mannanase isoforms as revealed by in-gel activity assay. Except for higher activities of CAT, POX and APX, cotyledonary activities of CW-POX, mannanase and polygacturonase and to some extent ß- 1, 4-D glucanase remained unaffected by HCN. Thus short term ROS accumulation in HCN-treated EA is due to declined SOD and POX activities. In long term the enhanced activities of both NADPH oxidase: CW-POX couple and cell wall-modifying enzymes in EA bring about wall loosening in preparation for radicle emergence. Evidences for the simultaneous operation of both mechanisms are provided in walnut EAs during dormancy release.


Assuntos
Cianeto de Hidrogênio/farmacologia , Juglans/fisiologia , Dormência de Plantas/efeitos dos fármacos , Espécies Reativas de Oxigênio/metabolismo , Parede Celular/metabolismo , Juglans/efeitos dos fármacos , Nozes/efeitos dos fármacos , Nozes/fisiologia , Oxirredução
6.
Diabetes Metab Res Rev ; 34(7): e3031, 2018 10.
Artigo em Inglês | MEDLINE | ID: mdl-29927053

RESUMO

BACKGROUND: Dietary interventions and cohort studies relating tree nut consumption to blood glucose levels suggest a possible effect of walnuts. OBJECTIVE: To examine the associations between walnut consumption and diabetes risk using data from the National Health and Nutrition Examination Survey. METHODS: National Health and Nutrition Examination Survey data on adults conducting 24-hour dietary recall was pooled across the years 1999 through 2014. Diabetes status or risk was based on self-report, medication use, fasting plasma glucose levels, and haemoglobin A1c (HbA1c ) levels. Individuals were characterized based on reported consumption of walnuts, mixed-nuts, or no nuts. RESULTS: After adjustment for covariates, walnut consumers showed lower risk for diabetes compared with non-nut consumers based on self-report (odds ratio of 0.47, 95% confidence interval [CI] 0.31-0.72) as well as fasting blood glucose (relative risk ratio 0.32, CI 0.17-0.58) and HbA1c (relative risk ratio 0.51, CI 0.27-0.99). For each standard deviation of increase in walnut intake, prevalence of diabetes dropped 47%. The gender by walnut interaction suggests that the effect may be more potent among women than men (dose response P = .061). CONCLUSIONS: Both among individuals with known diabetes and those diagnosed based on elevated diabetes blood markers, the prevalence of individuals with diabetes was significantly lower among the walnut consumers. A possible gender-specific effect invites further attention.


Assuntos
Diabetes Mellitus Tipo 2/epidemiologia , Dieta , Comportamento Alimentar , Juglans , Nozes , Adulto , Idoso , Estudos Transversais , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Inquéritos Nutricionais , Nozes/fisiologia , Fatores de Risco , Estados Unidos/epidemiologia
7.
Bioinspir Biomim ; 12(2): 026009, 2017 02 28.
Artigo em Inglês | MEDLINE | ID: mdl-28245197

RESUMO

Here we investigate the mechanical properties and structural design of the pericarp of the green coconut (Cocos nucifera L.). The pericarp showed excellent impact characteristics, and mechanical tests of its individual components revealed gradients in stiffness, strength and elongation at break from the outer to the inner layer of the pericarp. In order to understand more about the potential effect of such gradients on 'bulk' material properties, we designed simple, graded, cellulose fibre-reinforced polylactide (PLA) composites by stacking layers reinforced with fibres of different mechanical properties. Tensile properties of the graded composites were largely determined by the 'weakest' fibre, irrespective of the fibre distribution. However, a graded design led to pronounced asymmetric bending and impact properties. Bio-inspired, asymmetrically graded composites showed a flexural strength and modulus comparable to that of the strongest reference samples, but the elongation at maximum load was dependent on the specimen orientation. The impact strength of the graded composites showed a similar orientation-dependence, and peak values exceeded the impact strength of a non-graded reference composite containing identical fibre fractions by up to a factor of three. In combination, our results show that an asymmetric, systematic variation of fibre properties can successfully combine desirable properties of different fibre types, suggesting new routes for the development of high-performance composites, and improving our understanding of the structure-function relationship of the coconut pericarp.


Assuntos
Materiais Biomiméticos , Cocos/anatomia & histologia , Elasticidade , Nozes/anatomia & histologia , Nozes/fisiologia , Poliésteres , Resistência à Tração , Boehmeria , Cannabis , Celulose , Teste de Materiais
8.
Glob Chang Biol ; 21(11): 4196-209, 2015 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-26149833

RESUMO

Climate change is predicted to increase the aridity in the Mediterranean Basin and severely affect forest productivity and composition. The responses of forests to different timescales of drought, however, are still poorly understood because extreme and persistent moderate droughts can produce nonlinear responses in plants. We conducted a rainfall-manipulation experiment in a Mediterranean forest dominated by Quercus ilex, Phillyrea latifolia, and Arbutus unedo in the Prades Mountains in southern Catalonia from 1999 to 2014. The experimental drought significantly decreased forest aboveground-biomass increment (ABI), tended to increase the litterfall, and decreased aboveground net primary production throughout the 15 years of the study. The responses to the experimental drought were highly species-specific. A. unedo suffered a significant reduction in ABI, Q. ilex experienced a decrease during the early experiment (1999-2003) and in the extreme droughts of 2005-2006 and 2011-2012, and P. latifolia was unaffected by the treatment. The drought treatment significantly increased branch litterfall, especially in the extremely dry year of 2011, and also increased overall leaf litterfall. The drought treatment reduced the fruit production of Q. ilex, which affected seedling recruitment. The ABIs of all species were highly correlated with SPEI in early spring, whereas the branch litterfalls were better correlated with summer SPEIs and the leaf and fruit litterfalls were better correlated with autumn SPEIs. These species-specific responses indicated that the dominant species (Q. ilex) could be partially replaced by the drought-resistant species (P. latifolia). However, the results of this long-term study also suggest that the effect of drought treatment has been dampened over time, probably due to a combination of demographic compensation, morphological and physiological acclimation, and epigenetic changes. However, the structure of community (e.g., species composition, dominance, and stand density) may be reordered when a certain drought threshold is reached.


Assuntos
Mudança Climática , Secas , Ericaceae/fisiologia , Oleaceae/fisiologia , Quercus/fisiologia , Aclimatação , Biomassa , Ericaceae/crescimento & desenvolvimento , Florestas , Nozes/crescimento & desenvolvimento , Nozes/fisiologia , Oleaceae/crescimento & desenvolvimento , Folhas de Planta/crescimento & desenvolvimento , Folhas de Planta/fisiologia , Brotos de Planta/crescimento & desenvolvimento , Brotos de Planta/fisiologia , Quercus/crescimento & desenvolvimento , Espanha , Estresse Fisiológico
9.
J Food Sci ; 79(7): H1443-53, 2014 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-24974969

RESUMO

UNLABELLED: In this article, tissue layers and cells characteristics of the Brazil nut (Bertholletia excelsa H.B.K.) shell (tegument), brown skin (testae), and edible part (cotyledons) were identified by stereoscopy (SM) and scanning electron microscopies (SEM). (a) The shell (a lignin rich, protective wall) varies in thickness throughout the nut structure and comprises different tissue types (total 3)/texture (hard/mid-hard/soft), layers (2 to 5), colors (light to dark brown and white to cream), cell shape (amorphous/flattened on both surfaces; polygonal and cylindrical with thick, porous primary and secondary wall in cross-section), and vascular distribution (helically and polyedrical thickened vessels at soft tissue and locule/channel structures). These variations are observed either in the shell faces, face corners, nut tips, or locule in testae. (b) The brown skin (shell nut part linked to both the shell and edible part) is made of flattened irregular-shaped parenchymal cells distributed in several layers with more flexible fibrous, thinner wall tissue than shell. It has both rough and smooth shiny texture on the upper and lower surfaces, respectively. However, the nut (c) edible part, that is the nut storage tissue, shows several different tissue/cell layers starting from epidermis (double/triple cells sequence of round and palisade shapes) layer-the endosperm tissue. The parenchymal tissues show cells of irregular shape with small and larger sizes distributed in regular and randomly layers, respectively, separated by a short meristem tissue layer. The cortex cells increase in size as they approach the cotyledons junction. The Brazil nut part's tissue layers and cells were identified by the SM and SEM microscopy methods applied, which provides knowledge for further understanding of nut alterations that may occur either in the forest or during the factory processing. PRACTICAL APPLICATION: Knowledge about the characteristics and nature of the waste woody tissues from the Brazil nut factories is of interest for potential applications in the industry. Understanding the nut tissues and cells structures helps in judging how much whole nut edible part gets spoiled/deteriorated (either raw or processed), for further development of procedures to prevent and/or control such spoiling/deterioration for achieving nut quality and safety (to be discussed in Part Two).


Assuntos
Bertholletia/ultraestrutura , Nozes/ultraestrutura , Bertholletia/fisiologia , Análise de Alimentos , Microscopia Eletrônica de Varredura , Nozes/fisiologia
10.
J Econ Entomol ; 106(2): 1071-4, 2013 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-23786103

RESUMO

A no-choice test was performed to determine survival and reproductive capacity of stored-product insect pests on pecan, Carya illinoensis (Wangenheim) Koch. Insects used were Indianmeal moth, Plodia interpunctella (Hübner) (Lepidoptera: Pyralidae); sawtoothed grain beetle, Oryzaephilus surinamensis (L.) (Coleoptera: Cucujidae); red flour beetle, Tribolium castaneum (Herbst) (Coleoptera: Tenebrionidae); lesser grain borer, Rhyzopertha dominica (F.) (Coleoptera: Bostrichidae); and rusty grain beetle, Cryptolestes ferrugineus (Stephens) (Coleoptera: Laemophloeidae). Fifty adults of each beetle species or 10 reproductive pairs of P. interpunctella adults were placed in 0.5-liter containers with either whole-shell pecans, cracked-shell pecans, randomly selected in-shell pecans, pecan nutmeats, cracked wheat, or glass beads and held at 28 degrees C, 60-70% relative humidity, and 16:8 (L:D) photoperiod for 2, 4, 6, and 8 wk. Four replications of each insect-diet-interval combination were performed. Larvae of P. interpunctella, O. surinamensis, T. castaneum, C. ferrugineus, and adult P. interpunctella and O. surinamensis developed on cracked and nutmeat pecan diets. R. dominica did not complete reproduction on pecans. Knowledge that these pests can reproduce on stored pecan will assist pecan growers, accumulators, and storage facilities in preventing insect outbreaks on their product.


Assuntos
Carya/fisiologia , Besouros/fisiologia , Mariposas/fisiologia , Animais , Comportamento Alimentar , Nozes/fisiologia , Reprodução , Fatores de Tempo
11.
PLoS One ; 6(5): e20155, 2011.
Artigo em Inglês | MEDLINE | ID: mdl-21629649

RESUMO

BACKGROUND: Temperate fruit and nut trees require adequate winter chill to produce economically viable yields. Global warming has the potential to reduce available winter chill and greatly impact crop yields. METHODOLOGY/PRINCIPAL FINDINGS: We estimated winter chill for two past (1975 and 2000) and 18 future scenarios (mid and end 21st century; 3 Global Climate Models [GCMs]; 3 greenhouse gas emissions [GHG] scenarios). For 4,293 weather stations around the world and GCM projections, Safe Winter Chill (SWC), the amount of winter chill that is exceeded in 90% of all years, was estimated for all scenarios using the "Dynamic Model" and interpolated globally. We found that SWC ranged between 0 and about 170 Chill Portions (CP) for all climate scenarios, but that the global distribution varied across scenarios. Warm regions are likely to experience severe reductions in available winter chill, potentially threatening production there. In contrast, SWC in most temperate growing regions is likely to remain relatively unchanged, and cold regions may even see an increase in SWC. Climate change impacts on SWC differed quantitatively among GCMs and GHG scenarios, with the highest GHG leading to losses up to 40 CP in warm regions, compared to 20 CP for the lowest GHG. CONCLUSIONS/SIGNIFICANCE: The extent of projected changes in winter chill in many major growing regions of fruits and nuts indicates that growers of these commodities will likely experience problems in the future. Mitigation of climate change through reductions in greenhouse gas emissions can help reduce the impacts, however, adaption to changes will have to occur. To better prepare for likely impacts of climate change, efforts should be undertaken to breed tree cultivars for lower chilling requirements, to develop tools to cope with insufficient winter chill, and to better understand the temperature responses of tree crops.


Assuntos
Mudança Climática , Árvores/fisiologia , Frutas/crescimento & desenvolvimento , Frutas/fisiologia , Nozes/crescimento & desenvolvimento , Nozes/fisiologia , Temperatura , Árvores/crescimento & desenvolvimento
12.
Int J Biometeorol ; 55(3): 411-21, 2011 May.
Artigo em Inglês | MEDLINE | ID: mdl-20730614

RESUMO

Many fruit and nut trees must fulfill a chilling requirement to break their winter dormancy and resume normal growth in spring. Several models exist for quantifying winter chill, and growers and researchers often tacitly assume that the choice of model is not important and estimates of species chilling requirements are valid across growing regions. To test this assumption, Safe Winter Chill (the amount of winter chill that is exceeded in 90% of years) was calculated for 5,078 weather stations around the world, using the Dynamic Model [in Chill Portions (CP)], the Chilling Hours (CH) Model and the Utah Model [Utah Chill Units (UCU)]. Distributions of the ratios between different winter chill metrics were mapped on a global scale. These ratios should be constant if the models were strictly proportional. Ratios between winter chill metrics varied substantially, with the CH/CP ratio ranging between 0 and 34, the UCU/CP ratio between -155 and +20 and the UCU/CH ratio between -10 and +5. The models are thus not proportional, and chilling requirements determined in a given location may not be valid elsewhere. The Utah Model produced negative winter chill totals in many Subtropical regions, where it does not seem to be useful. Mean annual temperature and daily temperature range influenced all winter chill ratios, but explained only between 12 and 27% of the variation. Data on chilling requirements should always be amended with information on the location and experimental conditions of the study in which they were determined, ideally including site-specific conversion factors between winter chill models. This would greatly facilitate the transfer of such information across growing regions, and help prepare growers for the impact of climate change.


Assuntos
Clima , Temperatura Baixa , Modelos Biológicos , Estações do Ano , Árvores/fisiologia , Mudança Climática , Frutas/crescimento & desenvolvimento , Frutas/fisiologia , Internacionalidade , Nozes/crescimento & desenvolvimento , Nozes/fisiologia , Fatores de Tempo , Árvores/crescimento & desenvolvimento , Utah
13.
J Nutrigenet Nutrigenomics ; 1(3): 109-17, 2008.
Artigo em Inglês | MEDLINE | ID: mdl-19776620

RESUMO

The metabolic syndrome has attracted interest because of its relevance to major contemporary chronic diseases associated with inactive lifestyles and the abundance of food, both of which have resulted in a way of life which challenges our genetic makeup. Changing the fuel mix by the introduction of more monounsaturated and polyunsaturated fatty acids, a reduction in saturated fatty acids, an increase in fiber, and the use of low glycemic index slow-release carbohydrate foods may make a difference, as will increasing the amount of vegetable protein and plant foods such as nuts, rich in monounsaturated fatty acids and antioxidant systems. Nevertheless, these supportive measures will be overwhelmed in the absence of calorie restriction combined with adequate energy expenditure. This situation appears to be one where the subsidiary solutions are complex and the central issue is simple.


Assuntos
Síndrome Metabólica/etiologia , Fenômenos Fisiológicos da Nutrição , Consumo de Bebidas Alcoólicas/sangue , Consumo de Bebidas Alcoólicas/metabolismo , Animais , Restrição Calórica , Dieta Aterogênica , Carboidratos da Dieta/efeitos adversos , Carboidratos da Dieta/farmacologia , Fibras na Dieta/farmacologia , Índice Glicêmico/fisiologia , Humanos , Nozes/fisiologia , Fatores de Risco , Alimentos de Soja
14.
Tree Physiol ; 24(3): 303-12, 2004 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-14704139

RESUMO

We investigated the effects of regulated deficit irrigation (RDI) during the pre-harvest period (kernel-filling stage) on water relations, leaf development and crop yield in mature almond (Prunus dulcis (Mill.) D.A. Webb cv. Cartagenera) trees during a 2-year field experiment. Trees were either irrigated at full-crop evapotranspiration (ETc=100%) (well-irrigated control treatment) or subjected to an RDI treatment that consisted of full irrigation for the full season, except from early June to early August (kernel-filling stage), when 20% ETc was applied. The severity of water stress was characterized by measurements of soil water content, predawn leaf water potential (Psipd) and relative water content (RWC). Stomatal conductance (gs), net CO2 assimilation rate (A), transpiration rate (E), leaf abscission, leaf expansion rate and crop yield were also measured. In both years, Psipd and RWC of well-irrigated trees were maintained above -1.0 MPa and 92%, respectively, whereas the corresponding values for trees in the RDI treatment were -2.37 MPa and 82%. Long-term water stress led to a progressive decline in gs, A and E, with significant reductions after 21 days in the RDI treatment. At the time of maximum stress (48 days after commencement of RDI), A, gs and E were 64, 67 and 56% lower than control values, respectively. High correlations between A, E and gs were observed. Plant water status recovered within 15 days after the resumption of irrigation and was associated with recovery of soil water content. A relatively rapid and complete recovery of A and gs was also observed, although the recovery was slower than for Psipd and RWC. Severe water stress during the kernel-filling stage resulted in premature defoliation (caused by increased leaf abscission) and a reduction in leaf growth rate, which decreased tree leaf area. Although kernel yield was correlated with leaf water potential, RDI caused a nonsignificant 7% reduction in kernel yield and had no effect on kernel size. The RDI treatment also improved water-use efficiency because about 30% less irrigation water was applied in the RDI treatment than in the control treatment. We conclude that high-cropping almonds can be successfully grown in semiarid regions in an RDI regime provided that Psipd is maintained above a threshold value of -2 MPa.


Assuntos
Folhas de Planta/crescimento & desenvolvimento , Prunus/fisiologia , Árvores/fisiologia , Agricultura , Nozes/fisiologia , Folhas de Planta/fisiologia , Transpiração Vegetal/fisiologia , Prunus/crescimento & desenvolvimento , Árvores/crescimento & desenvolvimento , Água
15.
FEBS Lett ; 467(2-3): 206-10, 2000 Feb 11.
Artigo em Inglês | MEDLINE | ID: mdl-10675539

RESUMO

A cysteine proteinase inhibitor (cystatin) from chestnut (Castanea sativa) seeds, designated CsC, has been previously characterized. Its antifungal, acaricide and inhibitory activities have allowed to involve CsC in defence mechanisms. The CsC transcription levels decreased during seed maturation and increased throughout germination, an opposite behavior to that shown by most phytocystatins. No inhibition of endogenous proteinase activity by purified CsC was found during the seed maturation or germination processes. CsC message accumulation was induced in chestnut leaves after fungal infection, as well as by wounding and jasmonic acid treatment. Induction in roots was also observed by the last two treatments. Furthermore, CsC transcript levels strongly raised, both in roots and leaves, when chestnut plantlets were subjected to cold- and saline-shocks, and also in roots by heat stress. All together, these data suggest that chestnut cystatin is not only involved in defence responses to pests and pathogen invasion, but also in those related to abiotic stress.


Assuntos
Cistatinas/biossíntese , Nozes/fisiologia , Acetatos , Temperatura Baixa , Ciclopentanos , Cistatinas/genética , Inibidores Enzimáticos/metabolismo , Germinação , Temperatura Alta , Nozes/genética , Nozes/microbiologia , Oxilipinas , Reguladores de Crescimento de Plantas , Proteínas de Plantas , Cloreto de Sódio
16.
Am J Clin Nutr ; 70(3 Suppl): 504S-511S, 1999 09.
Artigo em Inglês | MEDLINE | ID: mdl-10479223

RESUMO

Because nuts have favorable fatty acid and nutrient profiles, there is growing interest in evaluating their role in a heart-healthy diet. Nuts are low in saturated fatty acids and high in monounsaturated and polyunsaturated fatty acids. In addition, emerging evidence indicates that there are other bioactive molecules in nuts that elicit cardioprotective effects. These include plant protein, dietary fiber, micronutrients such as copper and magnesium, plant sterols, and phytochemicals. Few feeding studies have been conducted that have incorporated different nuts into the test diets to determine the effects on plasma lipids and lipoproteins. The total- and lipoprotein-cholesterol responses to these diets are summarized in this article. In addition, the actual cholesterol response was compared with the predicted response derived from the most current predictive equations for blood cholesterol. Results from this comparison showed that when subjects consumed test diets including nuts, there was an approximately 25% greater cholesterol-lowering response than that predicted by the equations. These results suggest that there are non-fatty acid constituents in nuts that have additional cholesterol-lowering effects. Further studies are needed to identify these constituents and establish their relative cholesterol-lowering potency.


Assuntos
Colesterol/sangue , Dieta , Ácidos Graxos/farmacologia , Lipoproteínas/sangue , Nozes/química , Gorduras/análise , Ácidos Graxos/análise , Humanos , Valor Nutritivo , Nozes/fisiologia , Nozes/uso terapêutico , Fitoterapia , Valor Preditivo dos Testes
17.
Plant Physiol ; 112(3): 975-85, 1996 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-8938406

RESUMO

Genetic constructs in which different N- and C-terminal segments of Brazil nut (Bertholletia excelsa H.B.K.) 2S albumin were fused to secretory yeast invertase were transformed into tobacco (Nicotiana tabacum) plants to investigate the vacuolar targeting signal of the 2S albumin. None of the N-terminal segments, including the complete precursor containing all propeptides, was able to direct the invertase to the vacuoles. However, a short C-terminal segment comprising the last 20 amino acids of the precursor was sufficient for efficient targeting of yeast invertase to the vacuoles of the transformed tobacco plants. Further analyses showed that peptides of 16 and 13 amino acids of the C-terminal segment were still sufficient, although they had slightly lower efficiency. When segments of 9 amino acids or shorter were analyzed, a decrease to approximately 30% was observed. These segments included the C-terminal propeptide of four amino acids (Ile-Ala-Gly-Phe). When the 2S albumin was expressed in tobacco, it was also localized to the vacuoles of mesophyll cells. If the C-terminal propeptide was deleted from the 2S albumin precursor, all of this truncated 2S albumin was secreted from the tobacco cells. These results indicate that the C-terminal propeptide is necessary but not sufficient for vacuolar targeting. In addition, an adjacent segment of at least 12 amino acids of the mature protein is needed to form the complete signal for efficient targeting.


Assuntos
Albuminas/biossíntese , Nozes/fisiologia , Proteínas de Plantas/biossíntese , Precursores de Proteínas/biossíntese , Sinais Direcionadores de Proteínas/metabolismo , Albuminas 2S de Plantas , Albuminas/química , Sequência de Aminoácidos , Antígenos de Plantas , Glicosídeo Hidrolases/biossíntese , Dados de Sequência Molecular , Nozes/genética , Proteínas de Plantas/química , Plantas Geneticamente Modificadas , Plantas Tóxicas , Precursores de Proteínas/química , Sinais Direcionadores de Proteínas/química , Proteínas Recombinantes de Fusão/biossíntese , Saccharomyces cerevisiae/genética , Nicotiana , Vacúolos/metabolismo , beta-Frutofuranosidase
18.
Eur J Clin Nutr ; 47 Suppl 1: S71-5, 1993 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-8269904

RESUMO

Nuts are part of the Mediterranean tradition. For millennia, tree nuts have been in the region. Results of an epidemiological study conducted among California Adventists provide strong evidence that frequent consumption of nuts have a protective effect on both fatal and non-fatal ischaemic heart disease events. The unique nutrient composition of nuts makes it plausible that nuts favourably affect heart disease risk factors and interfere with the process of atherogenesis. Results of recently conducted human nutritional studies, with varying degrees of methodological rigour, all seem to indicate that eating nuts lowers serum cholesterol and favourably modifies the lipoprotein profile. The effects of nut consumption on other cardiovascular disease risk factors deserve further exploration.


Assuntos
Dieta , Isquemia Miocárdica/prevenção & controle , Nozes , Colesterol/sangue , Inquéritos sobre Dietas , Humanos , Lipoproteínas/sangue , Isquemia Miocárdica/sangue , Isquemia Miocárdica/epidemiologia , Nozes/fisiologia , Modelos de Riscos Proporcionais , Estudos Prospectivos , Fatores de Risco
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