首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 15 毫秒
1.
Cassava (Manihot esculenta Crantz) is a cyanide-containing root crop used by many indigenous groups in Amazonia. Despite the availability of low-cyanogenic potential (CNP) cassava, the Tukanoans of the Colombian Amazon region and many other indigenous groups in lowland Amazonia cultivate primarily high-CNP cassava as their staple crop. Based on the assumption that the Tukanoan preference for high-CNP cultivars is due, in part, to the ability of these cultivars to consistently produce higher yields, we tested the null hypothesis that low-CNP cassava has yields that are greater than or equal to the yields of high-CNP cultivars in Tukanoan gardens. To do so we compared the yields of low- and high-CNP cassava in 10 Tukanoan gardens and in one control garden. We reject the null hypothesis: high-CNP cultivars yielded more than low-CNP cultivars in both traditional Tukanoan Indian gardens and a control garden. Although there are several possible explanations for the differences in yields, the most plausible inference is that the high-CNP plants are more likely to be disease and/or insect resistant.  相似文献   

2.
Building on a previous experiment to apply Strathern's discussions of Melanesian gift exchange to ethnography relating to Tukanoan societies in Northwest Amazonia, this essay asks why other authors should repeatedly affirm that the gift has no relevance in the Amazonian context. Two answers are proposed. Firstly, the authors concerned tend to assume that a particular type of social formation is characteristic of Amazonia as a whole. The Tukanoans, who engage in ceremonial exchange of food and goods, do not fit this rubric. Secondly, despite their differences, these authors assume that Amazonian societies are bride‐service societies where, axiomatically, there can be no gift. The Tukanoans are not bride‐service societies and, if anything, tend towards the bride‐wealth alternative. This Tukanoan exception serves to re‐emphasize the diversity of Amazonian social formations, one that would have been even greater in the archaeological past. It also warns against the dangers of over‐hasty theoretical closure.  相似文献   

3.
Cranberries (Vaccinium macrocarpon Ait.) are an economically important fruit crop derived from a North American native species. We report the application of 12 simple sequence repeats (SSR) or microsatellite markers to assess the genetic diversity of cranberry cultivars. We studied 164 samples of 21 different cranberry cultivars, 11 experimental hybrids, and 6 representative accessions of wild species. Genetic cluster analysis, based on 117 SSR alleles, differentiated the major cranberry cultivars. However, some cranberry cultivar subclone variants and mislabeled samples were observed. Consensus genetic profiles identified the most likely clonal representatives of several important cranberry cultivars (e.g., “Ben Lear,” “Howes,” and “Stevens”). The markers were further used to confirm putative parents of several hybrid progenies. The long-term goal of our studies is to identify, preserve, and utilize unique genetic materials to breed improved cranberries. Attaining this goal will help growers maintain sustainability under changing economic and environmental conditions.  相似文献   

4.
Chromosome arm 1RS of rye (Secale cereale) is a valuable resource for wheat (Triticum aestivum) improvement. 1AL.1RS and 1BL.1RS translocations play an important role in wheat breeding, since wheat carrying these chromosomal translocations has higher tolerance to biotic and abiotic stress. In this study, the presence of 1RS and the distribution of 1AL.1RS and 1BL.1RS wheat-rye translocations were examined in 66 Iranian cultivars and 70 regional foreign accessions of bread wheat, using three rye-specific primers (“RYER3/F3”, “O-SEC5′-A/O-SEC3′-R”, “PAWS5/S6”). Based on “RyeR3/F3”, the presence of 1RS was verified in 15 (23%) Iranian cultivars and in two (3%) foreign accessions. Further, “O-SEC5′-A/O-SEC3′-R” and “PAWS5/S6” were used to distinguish 1AL.1RS and 1BL.1RS translocations. According to results from these primers, 1BL.1RS was identified in 14 (21%) Iranian cultivars and two (3%) foreign accessions. The results confirm that “Sholeh” is the only cultivar (1.5%), among all cultivars and accessions, that carries 1AL.1RS. This study provides a useful tool in marker-assisted selection of materials containing 1RS, and in the creation of new Iranian common wheat cultivars with a larger genetic diversity in wheat breeding programs.  相似文献   

5.
Finn B. Hansen  Peter Nicholls 《BBA》1978,502(3):400-408
1. Carbon monoxide (CO) acts competitively towards oxygen when the latter is taken up in respiration by cytochrome aa3-containing proteoliposomes, both in the presence of p-trifluoromethoxy carbonyl cyanide phenylhydrazone and valinomycin (deenergized state) and in their absence (energized state). At high levels of CO, the double reciprocal plots (1v vs. 1[O2]) in the energized and deenergized states are parallel, i.e. energization acts “anti-competitively” towards oxygen, and the “respiratory control ratio” decreases as the oxygen concentration decreases.2. Azide acts non-competitively towards cytochrome c when the latter is oxidized by cytochrome aa3-containing proteoliposomes both in the energized and deenergized (plus p-trifluoromethoxy carbonyl cyanide phenylhydrazone and valinomycin) conditions. At low azide concentrations the apparent Ki for azide is unaffected by energization, but at high azide levels the Ki increases in energized liposomes, i.e. the “respiratory control ratio” decreases as the azide concentration increases.3. It is concluded that the inhibitor experiments are consistent with but do not prove the concept that the oxidase molecules in a single vesicle are responding to a single “energization state” or set of electrochemical gradients. This and other models are discussed.  相似文献   

6.
Professional and popular publications have increasingly depicted native peoples of Amazonia as “natural” conservationists or as people with an innate “conservation ethic.” A few classic examples are cited repeatedly to advance this argument with the result that these cases tend to be generalized to all indigenous peoples. This paper explores the premise that many of these systems of resource conservation come from areas of Amazonia where human survival depends on careful management of the subsistence base and not from a culturally imbedded “conservation ethic.” Where resource constraints do not pertain, as in the case of the Yuquí of lowland Bolivia, such patterns are unknown. Finally, the negative consequences of portraying all native peoples as natural conservationists is having some negative consequences in terms of current struggles to obtain indigenous land rights.  相似文献   

7.
We report temporal variation and an “outbreak” of frog predation by moustached tamarins, Saguinus mystax, in north-eastern Peruvian Amazonia. Frog predation rates were generally very low, but strongly increased in October 2015. Other high rates, identified by outlier analyses, were also observed in September–November of other years. Over all study years, predation rates in this 3-month period were significantly higher than those in the remainder of the year, suggesting a seasonal pattern of frog predation by tamarins. Reduced fruit availability or increased frog abundance or a combination of both may be responsible for both the seasonal pattern and the specific “outbreak” of frog predation.  相似文献   

8.
In the processing field, there is a saying that “seed drugs be stir-fried”. Bitter almond (BA) is a kind of seed Chinese medicine. BA need be used after being fried. To distinguish raw bitter almonds (RBA) from processed products and prove the rationality of “seed drugs be stir-fried”, we analyzed the RBA and five processed products (scalded bitter almonds, fried bitter almonds, honey fried bitter almonds, bran fried bitter almonds, bitter almonds cream) using RP-HPLC fingerprints and chemometric methods. The similarity between RBA and processed products was 0.733∼0.995. Hierarchically clustered heatmap was used to evaluate the changes in components. Principal component analysis (PCA) was used for classification, and all samples are distinguished according to RBA and five processing methods. Six chemical markers were obtained by partial least squares discriminant analysis (PLS-DA). The content and degradation rate of amygdalin and β-glucosidase activity were determined. Compared with RBA, the content and degradation rate of amygdalin, and β-glucosidase activity were increased in bitter almonds cream. The content and degradation rate were decreased, and β-glucosidase was inactivated in other processed products. The above results showed that stir-frying had the best effect. The results showed that processing can ensure the stability of RBA quality, and the saying “seed drugs be stir-fried” is reasonable.  相似文献   

9.
Cotton (Gossypium hirsutum) wilt caused by Fusarium oxysporum f. sp. vasinfectum (Fov) is considered as a major threat for commercial cotton production worldwide. Relative expression ratios of two key pathogenesis-related (PR) genes (PR-3 and PR-10) and a detoxification gene (GST18) were compared between a fully susceptible (“LACTA”) and a partially field-resistant (“EMERALD”) cultivar after challenging with an Australian Fov isolate, as well as after pre-treatments with chemical inducers of defense such as BION® (a chemical analog of salicylic acid) and methyl-jasmonate (MeJA) prior to Fov inoculation. It was demonstrated that in both hypocotyls and roots of “EMERALD”, all PR genes were over-expressed after inoculation with Fov but not in the fully susceptible cultivar. Fov inoculation did not significantly affect GST18 expression in both cultivars. Exogenous application of each defense elicitor, prior to Fov inoculation, resulted in up-regulation of the three genes in root tissues of the fully susceptible cultivar. BION® application did not influence PR-3 expression in hypocotyls of both cultivars, whereas MeJA application resulted in induction of PR-3 in both cultivars. Furthermore, in hypocotyls of “LACTA”, over-expression of PR-10 was recorded after treatment with each chemical inducer. This pathogen exhibited different ability in eliciting oxidative burst in roots of the two cotton cultivars used in our analysis.  相似文献   

10.
11.
Germinating pea (Pisum sativum L.) seeds of two dwarf cultivars, “Progress No. 9” and “Green Arrow”, and two tall cultivars, “Alaska” and “Alderman”, were treated with low temperature (3–5°C) for 14 days and then transferred to normal growing conditions (19–21°C for 16 h/14.5–16.5°C for 8 h) for an additional 10 days. Biosynthesis of [14C]ent-kaurene from [14C]2-mevalonic acid (2-MVA) was assayed in cell-free enzyme extracts prepared from shoot tips 10 days after cold treatment and was compared with activity in enzyme extracts prepared from noncold-treated, 10-day-old control plants. Shoot lengths of cold-treated plants were measured throughout a 35-day period and compared with shoot lengths of plants grown without cold treatment for 25–35 days. Low temperature induced a five-to 10-fold enhancement ofent-kaurene, hence potentially gibberellin (GA), biosynthesis in seedlings of the two dwarf cultivars but not in the tall cultivars. However, the lack of an increase in growth rate in the cold-treated dwarfs indicated that endogenous GA biosynthesis remained blocked at some point beyondent-kaurene in the biosynthetic pathway. Since the late-flowering “Alderman” cultivar did not exhibit enhanced biosynthesis ofent-kaurene, it appears that if vernalization in late-flowering cultivars of peas is correlated with enhanced GA biosynthesis, it is not the early part of the biosynthetic pathway which is affected.  相似文献   

12.
Responses of photosynthetic rate and stomatal conductance to water stress as weI1 as the relationship between photosynthetic rate and stomatal conductance were investigated with soybean cultivars “Ludou No. 4” and “7605”. The former was a high yield cultivars widely used in Shandong province, and the latter was a small grain soybean line bred by Shandong Academy of Agricultural science. Soil water stress decreased leaf apparent photosynthetic rate and stomatal conductance of two soybean cultivars, and “Ludou No. 4” decreased more than “7605”. At the same value of water potential, photosynthetic rate and stomatal conductance of “7605” were higher than those of “Ludou No,4”,but the rate of stomatal closure for “7605” was higher than “Ludou No. 4”. Decreasing of stomatal conductance caused rising of leaf temperature of two soybean cultivars, and the rising of “7605” was more rapid than “Ludou No. 4”, but at the same treatment of water stress, leaf temperature of “Ludou No. 4” was higher than “7605”. Leaf water use efficiecy (WUE) of two soybean cultivars were decreased under water stress, and the rate of decreasing in “Ludou No.4” was more rapid than in “7605”. These results showed that “7605” was more resistant to water:stress than “Ludou No. 4”.  相似文献   

13.
Based on 261 single nucleotide polymorphism (SNP) markers, we analyzed 57 grapevine genotypes, consisting of 29 wild grapevines (Vitis vinifera subsp. sylvestris) prospected from the northwest part of Tunisia and 28 cultivated accessions (V. vinifera subsp. vinifera) maintained in the repository of the Arid Land Institute of Medenine (Tunisia). Pair-wise multilocus comparison with the ICVV SNP database allowed the identification of 13 cultivated genotypes, including ten synonymous groups with known Mediterranean or international varieties, three cases of color sports, and two misnomers. Genotypic analysis showed a high level of genetic diversity for both wild and cultivated groups. Multivariate and structure analyses clearly differentiated wild from cultivated grapevines and showed high average posterior probabilities of assignment to their group of origin. The clustering results largely supported the perceived classification and reflect that most of the present Tunisian cultivated varieties do not derive directly from the local wild populations but could correspond to materials introduced from different locations during historical times. Parentage analysis allowed the determination of the genetic origin of four Tunisian cultivars, “Garai”, “Jerbi” (from Kerkennah), “Mahdoui”, and “Reine de Vignes faux”, and showed that “Heptakilo” and “Planta Fina”, two old and widely distributed varieties in the Mediterranean basin, had an important role in the origin of Tunisian grapevines. The present study demonstrates the efficacy of SNP makers for germplasm characterization and genetic studies in grapevine.  相似文献   

14.
Amygdalin is a cyanogenic diglucoside and constitutes the bitter component in bitter almond (Prunus dulcis). Amygdalin concentration increases in the course of fruit formation. The monoglucoside prunasin is the precursor of amygdalin. Prunasin may be degraded to hydrogen cyanide, glucose, and benzaldehyde by the action of the β-glucosidase prunasin hydrolase (PH) and mandelonitirile lyase or be glucosylated to form amygdalin. The tissue and cellular localization of PHs was determined during fruit development in two sweet and two bitter almond cultivars using a specific antibody toward PHs. Confocal studies on sections of tegument, nucellus, endosperm, and embryo showed that the localization of the PH proteins is dependent on the stage of fruit development, shifting between apoplast and symplast in opposite patterns in sweet and bitter cultivars. Two different PH genes, Ph691 and Ph692, have been identified in a sweet and a bitter almond cultivar. Both cDNAs are 86% identical on the nucleotide level, and their encoded proteins are 79% identical to each other. In addition, Ph691 and Ph692 display 92% and 86% nucleotide identity to Ph1 from black cherry (Prunus serotina). Both proteins were predicted to contain an amino-terminal signal peptide, with the size of 26 amino acid residues for PH691 and 22 residues for PH692. The PH activity and the localization of the respective proteins in vivo differ between cultivars. This implies that there might be different concentrations of prunasin available in the seed for amygdalin synthesis and that these differences may determine whether the mature almond develops into bitter or sweet.  相似文献   

15.
Using immunochemical methods the authors investigated the evolutionary taxonomic distribution of the reserve seed protein “phaseolin” in cultivars ofPhaseolus vulgaris, in a series of species ofPhaseolus, and in representatives of some additional genera ofViciaceae. “Phaseolin” is typical of the seed ofPhaseolus vulgaris L.: it was detected in all 658 investigated cultivars — and also in species related toPhaseolus vulgaris L.(Ph. vulgaris L. ssp.aborigineus Burk.,Ph. polyanthus Green,Ph. dumosus Macf.,Ph. coccineus L., and in an undescribed species from the group ofPh. vulgaris L. -Ph. coccineus L.). A protein immunochemically somewhat similar to ?phaseolin“ occurs inPh. acufifolius A. Gray. In all other taxa“phaseolin” is absent.  相似文献   

16.
To estimate the steric distance between the bitter taste determinant sites in peptides, some cyclic dipeptides, amino acid anilides, amino acid cyclohexylamides, and benzoyl amino acids were synthesized and their tastes were evaluated. The diketopiperazine ring of cyclic dipeptides acted as a bitter taste determinant site due to its hydrophobicity. The steric distance between 2 sites was estimated as 4.1 Å from the molecule models of cyclic dipeptides composed of typical amino acids in the bitter peptides. Due to the hypothesis of two bitter taste determinant sites, which bind with the bitter taste receptor via a “binding unit” and a “stimulating unit,” a mechanism for the bitterness in peptides was postulated.  相似文献   

17.
Abstract

Cadmium (Cd) contamination is one of the most serious global environmental problems, and phytoremediation, which uses Cd-accumulator plants, is potentially one of the sustainable solutions. Pot experiments with natural and Cd-amended soils were conducted to investigate the accumulation of heavy metals in 10 leading cultivars of tobacco in China. The extraction ability and profiles of Cd accumulation among plant organs were also analyzed. The tobacco roots accumulated cobalt, nickel, and Cd, while the leaf highly bioaccumulated Cd and lowly accumulated zinc, selenium and mercury. The transport from the tobacco stem to the leaf plays a critical role in the accumulation of these elements. The ratios of Cd concentration in the leaves at lower, middle and upper positions were comparatively stable. The high Cd-extracting cultivars were “Hongda”, “NC89” and “Zhongyan 100” when grown in normal soils, “CuiBi 1” and “Hongda” in moderately contaminated soils, and “YuYan 87”, “LongJiang 851” and “K326” in severely contaminated soils. Tobacco leaves could accumulate about 80% of the total Cd extracted from the soil by the plant. Considering the Cd-extraction limitations exhibited by leading tobacco cultivars, screening of germplasm resources for high or low levels of Cd-accumulation is still an important target for the future.  相似文献   

18.
Specifying the relationship between pests and their host plants in terms of damage is one of the basic concepts of integrated pest management (IPM) programmes. The crop loss and economic injury level (EIL) of Tuta absoluta (Lepidoptera: Gelechiidae) were determined on different tomato cultivars using gain threshold (field experiment) and regression (semi‐field experiment) methods. By assessing the crop loss in 2015 and 2016, four out of seven infested tomato cultivars had a significant yield loss in terms of weight of total fruits versus the control under the open‐field conditions. However, the total number of tomato cultivars had no significant difference to control treatment. The semi‐field experiment included six treatments (0, 2, 4, 6, 8 and 10 gravid females/plant) and examined two tomato cultivars. The tomato cages with between 6 and 10 gravid females/plant showed the highest number and weight of damaged fruits. Based on pesticide control costs, the market value of tomato and the control efficacy, we determined the EIL for T. absoluta. In the field experiment, the EIL value for T. absoluta on “Petomech,” “Cal JN3,” “Rio Grande” and “Early Urbana Y” cultivars was 4.15, 4.47, 4.70 and 5.04 larvae per plant, respectively. Based on regression equations, we calculated the EIL values for T. absoluta on “Cal JN3” and “Early Urbana Y” to be 4.75 and 5.44 larvae/plant, respectively. Crop loss assessment and EIL are necessary components of cost‐effective IPM programs and can be effective tools for making decisions about the application of pesticides against T. absoluta.  相似文献   

19.
以3个转基因棉和2个亲本对照棉花品种为研究材料,分别测定了这5种棉花植株体内主要糖分与游离氨基酸含量;同时,分别用这5个棉花品种的叶片饲养棉蚜Aphis gossypii Glover并测定其蜜露分泌量及其主要营养成分。结果表明,转基因棉花“国抗22”叶片中葡萄糖、蔗糖、麦芽糖的平均含量及可溶性糖总量分别比亲本对照棉“泗棉3号”减少61.76%、 89.05%、77.86%和23.61%,转基因棉花“苏抗103”和“中抗310”叶片中葡萄糖、蔗糖、麦芽糖的平均含量及可溶性糖总量分别比亲本对照棉“苏棉12”下降14.15%、32.80%、92.22%、11.46% 和4 6.81%、93.19%、61.11%、43.91%,游离氨基酸总量及各种氨基酸、果糖、鼠李糖、海藻糖的含量在不同转基因棉与亲本对照棉花品种间也存在很大差异,其中一些处理间的差异达显著或极显著水平。这表明外源基因的导入已经影响到了转基因棉花品种中主要糖分与游离氨基酸的合成。棉蚜取食转基因棉花品种“国抗22”后,蜜露的日平均分泌量比取食对照品种“泗棉3号”减少40.54%,取食其他两个转基因棉花品种“苏抗103”和“中抗310”后蜜露的分泌量也比取食对照棉花品种“苏棉12”降低22.67%和30.0%,但棉蚜取食转基因棉花后蜜露中游离氨基酸的总量均高于对照棉花品种,蜜露中可溶性总糖、蔗糖和各种氨基酸含量在取食转基因棉和常规棉花品种间存在一定差异。  相似文献   

20.
The distinction between “bitter” and “sweet” (toxic and non-toxic) varieties of the cyanide-containing food crop manioc (Manihot esculenta, Euphorbiaceae) has a long tradition in the tropical forest areas of South and Central America where it was first cultivated. Yet this distinction has no taxonomic basis. The levels of cyanogenic glucosides found in manioc varieties not only vary widely, but do not correspond with any other known morphological or ecological feature. Nonetheless, these two “varieties” are commonly reported to have distinct geographical and cultural distributions and each is associated with a particular traditional food complex. This paper reviews the literature regarding the nature, distribution, and traditional uses of manioc varieties and concludes that (1) the geographical and cultural distribution of bitter and sweet varieties of manioc may not be as distinct as has been thought; (2) traditional categories of bitter and sweet manioc may stem more from culturally derived belief systems than from actual known levels of toxicity; and (3) the choice of complex and labor intensive processing methods usually associated with bitter manioc may not be required for detoxification but rather for the derived food products, particularly manioc flour.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号