Mg Of Seeds Research Articles

Sorghum seed coating with zinc: Physiological quality and initial performance of plants

Sorghum (Sorghum bicolor) is highly sensitive to zinc deficiency in soils, which results in decreased productivity and low-quality agricultural products. Our objective was to evaluate the effects of different zinc doses, applied to seeds, on the physiological quality and initial performance of sorghum plants. Six doses (0, 3.5, 7.0, 14.0, 21.0, and 28.0 g kg-1 seeds) were used and an uncoated control. The Zn coating process used dolomitic limestone as the filler and glue. Laboratory tests were conducted in a completely randomized design and greenhouse experiments were conducted in a randomized block design. The control means were 8, 9, and 14% lower than the maximum, minimum, and total seed area of treatments, respectively, relative to that of treatments. The control differed from other treatments by 10.47 in the speed index of emergence. Zinc at a dose of 28 g kg-1 seeds provided greater production of aerial dry matter, with nutrient content of 75.85 mg kg-1. Zinc on sorghum seeds affected length and dry matter production of aerial parts and roots but did not affect physical characteristics, germination, or emergence time. Applied zinc accumulated mainly in the roots, and promotes changes in Ca and Mg in seeds and other plant parts.

Effect of Topography on Maize Grains Elemental Profile: A Chemometric Approach

Background: The elemental composition of maize grains depends on the soil, land and environment characteristics where the crop grows. These effects are important to evaluate the availability of nutrients with complex dynamics, such as the concentration of macro and micronutrients in soils, which can vary according to different topographies. There is available scarce information about the influence of topographic characteristics (upland and lowland) where culture is developed with the mineral composition of crop products, in the present case, maize seeds. On the other hand, the study of the topographic effect on crops using multivariate analysis tools has not been reported. Objective: This paper assesses the effect of topographic conditions on plants, analyzing the mineral profiles in maize seeds obtained in two land conditions: uplands and lowlands. Materials and Methods: The mineral profile was studied by microwave plasma atomic emission spectrometry. Samples were collected from lowlands and uplands of cultivable lands of the north-east of La Pampa province, Argentina. Results: Differentiation of maize seeds collected from both topographical areas was achieved by principal components analysis (PCA), cluster analysis (CA) and linear discriminant analysis (LDA). PCA model based on mineral profile allowed to differentiate seeds from upland and lowlands by the influence of Cr and Mg variables. A significant accumulation of Cr and Mg in seeds from lowlands was observed. Cluster analysis confirmed such grouping but also, linear discriminant analysis achieved a correct classification of both the crops, showing the effect of topography on elemental profile. Conclusions: Multi-elemental analysis combined with chemometric tools proved useful to assess the effect of topographic characteristics on crops.

Sources of Nutrients for High-Yielding Winter Oilseed Rape (Brassica napus L.) during Post-Flowering Growth

Nutrient management by winter oilseed rape (WOSR) during the seed filling period (SFP) is crucial for seed density (SD), which subsequently determines seed yield (Y). This hypothesis was evaluated based on data from field experiments (2008-2010), with six treatments with sequentially added nutrients (0, NP, NPK, NPKMgS1(1/3 total MgS rate—spring applied), NPKMgS2 (total MgS rate autumn applied); NPKMgS3 (2/3-autumn, 1/3-spring). Nutrients accumulated in seeds were revealed as the most reliable WOSR trait, determining SD and Y. Yield was defined by the amounts of K and Mg in seeds. The amount nutrient remobilized from vegetative WOSR tissues was sufficient to cover the crop requirements during SFP for N, P, and Zn, but not for Ca, K, Mn, and Cu. The post-flowering K uptake resulted in PD, and SD increase, which subsequently resulted in a concomitant net uptake of Ca and Mg. The excessive accumulation of Ca, as well as Cu, and Mn in seeds due to a shortage of Mg, subsequently resulted in both SD and Y depression. The efficient exploitation of WOSR yielding potential as defined by SD, is possible, provided during the SFP reveals a net K and Mg uptake.

Impact of Magnetic Water on Soil Fertility and Faba Bean Productivity under Reducing Phosphorus Fertilizer Rates in Salt aAffected Soils.

This study aims to optimize of P fertilizers unit and alleviation soil salinity stress using irrigation with magnetic water. Two field trial using faba bean (Vicia faba L.; Variety Giza 843), were conducted at Agricultural Experimental Research Station of Tag El-ezz, Agricultural Research Centre, El-Mansoura Province, El-Dakhalia Governorate, Egypt during two successive winter seasons of 2015/16 and 2016/17. The experiment treatments were included two irrigation water treatment (normal and magnetized water) and three doses of P fertilizers (50, 75 and 100% from recommended P application). The two factors were layout in split plot design with three replicates, where the water and P fertilizers treatments were located randomly in the main and subplot respectively. The obtained results indicated that irrigation faba bean plants with magnetic-water treatment surpassed significantly irrigation with un-magnetized water under all dosses of P fertilizers in all recorded parameters except N and Na concentration in soil. Regarding irrigation with magnetic water, the increasing reached 21.45, 24.24 and 40.17% in plant height (cm), fresh plant weight (g) and seed yield (g plant-1) at harvest compared to irrigation with un-magnetized water of both seasons. As well as the improvements in concentration of N, P and K, Ca and Mg in seeds reached 19.01, 79.59, 49.43, 22.18, and 10.06 % respectively compared to irrigation with un-magnetized water. Finally, irrigation with magnetic water and P fertilizer at rate of 100% from recommended application is considered as most suitable treatment for obtaining the highest yield of faba bean under these experimental conditions.

Cryopreservation of immature and mature seeds of Brazilian orchids of the genus Cattleya

The aim of this study was to evaluate the efficiency of cryopreservation by the vitrification technique as a method of long-term conservation of immature seeds of the Cattleya harrisoniana × Cattleya walkeriana hybrid and of Cattleya tigrina with high water contents (49.35% and 65.60%, respectively) and mature seeds of Cattleya guttata with a low water content (6.15%). For each species or hybrid, the experiment was conducted in a completely randomized design with five treatments, namely, direct seed germination in vitro without PVS2 and without liquid nitrogen; PVS2 at 0 °C for 60 min without liquid nitrogen; PVS2 at 0 °C for 30 min or 1 h, followed by immersion in liquid nitrogen; and direct immersion of seeds in liquid nitrogen without PVS2. Five replicates were used. Each replicate was composed of a cryotube containing 15 mg of seeds. The following variables were evaluated after cryopreservation: seed viability, seed germination, seedling growth in vitro and seedling growth after acclimatization in a greenhouse. Plant genetic stability was examined by flow cytometry after in vitro culture. Anatomical analyses were carried out on the plants after acclimatization. Cryopreservation by vitrification was shown to be an effective and necessary method for the conservation of immature seeds of the C. harrisoniana × C. walkeriana hybrid and of C. tigrina with high water contents. For mature seeds of C. guttata with a low water content, direct immersion in liquid nitrogen without PVS2 was effective, and the use of vitrification was not required. These results demonstrate the effect of seed water content on cryopreservation. This unprecedented work examines the cryopreservation of the C. harrisoniana × C. walkeriana hybrid, C. guttata and C. tigrina from pollination to the production of acclimatized plants.

GC/MS analysis of morning glory seeds freely in commerce: can they be considered \u201cherbal highs\u201d?

BackgroundThe so-called “herbal highs” are substances derived from natural plants with effects on the central nervous system. Lisergamide, ergine or LSA is the basis of different types of drugs, which are in seeds of Ipomoea violacea, also known as Morning Glory, and other seeds.In our study we analysed the presence of lysergic acid amide (LSA) in seeds of Ipomoea violacea seized by the Italian Police, in others purchased through the Internet, and in other varieties of Ipomoea sold for ornamental purposes, to assess whether the actual consumption of ornamental seeds could contain hallucinogenic doses of LSA.MethodsThe analyses were conducted at the Laboratory of Forensic Toxicology of the Section of Legal Medicine of the University of Perugia, using GC/MSD system. For analysis, 300 mg of seeds (~8 seeds) from each specimen were chosen.ResultsAnalysis revealed that 300 mg of Ipomoea violacea seeds resulting from police seizures, equivalent to approximately 8 seeds, contained a percentage of LSA equal to 0.062%. This finding is in agreement with what was indicated in literature, as the ingestion of 250 seeds would lead to a dose of approximately 6 mg of LSA, capable of provoking hallucinogenic effects.The analysis of 300 mg of Ipomoea Rubrocerulea seeds bought on the commercial marketdetected an average concentration of LSA of 0.011%. The Ipomoea mix contained a concentration of LSA about 10 times lower than that of seized Morning Glory seeds.ConclusionSeeds bought on the commercial market contained doses of LSA capable of provoking hallucinogenic effects. In the absence of data on the toxicity resulting from the ingestion of seeds for ornamental purposes, we believe that further research on the actual safety of ornamental seeds is necessary.

ESTIMULACIÓN DE LA GERMINACIÓN Y DESARROLLO in vitro DE Laelia autumnalis CON RAYOS GAMMA

La germinación natural de las semillas de la orquídea L. autumnalis es baja, porque requiere condiciones específicas del árbol hospedero y factores ambientales favorables. La germinación asimbiótica in vitro es un método de propagación eficiente; sin embargo, el desarrollo de las plántulas requiere de uno a dos años. El objetivo fue evaluar el efecto de la radiación gamma 60Co para estimular la germinación de semillas y el desarrollo in vitro de plántulas de L. autumnalis. Se irradiaron 22 frutos a diferentes dosis (3 a 30 Gy, con intervalos de 3 Gy), además de un tratamiento sin irradiar utilizado como testigo. Las semillas se cultivaron en medio Murashige y Skoog sin fitohormonas. El diseño experimental fue completamente al azar con 16 a 32 repeticiones; la unidad experimental fue un frasco con 20 mg de semillas. A los cinco días y posteriormente cada 10 días se cuantificó el número de semillas en las etapas de imbibición, formación de protocormos fotosintéticos, protocormos en diferenciación, desarrollo de promeristemos, hojas y plántulas. Se realizó un análisis de varianza y prueba de Tukey (α = 0.05). Las semillas irradiadas entre 3 y 15 Gy formaron 61 % más protocormos fotosintéticos que las semillas sin tratar. Las semillas irradiadas con 3, 15 y 18 Gy formaron 73 % más promeristemos. Todos los protocormos tratados con 3 Gy formaron hojas 60 días después de la siembra (dds); en contraste, sólo 12.5 % de las semillas no tratadas formaron hojas. El 66.5 % de las semillas tratadas con 15 Gy desarrollaron plántulas a los 80 dds. Se confirmó el efecto radioestimulante de la radiación gamma a dosis bajas; con 3 Gy se formaron promeristemos, hojas y plántulas completas 20, 20 y 10 días, respectivamente, antes que en el tratamiento control. La radiación a dosis superiores fue negativa al retrasar la germinación y el desarrollo de plántulas.

Genetic diversity among cultivated and wild lentils for iron, zinc, copper, calcium and magnesium concentrations

Information on the seed mineral concentration of cultivated and wild lentils is limited. The objective of this study was to determine the concentrations of iron (Fe), zinc (Zn), calcium (Ca), copper (Cu), and magnesium (Mg) in the seeds of 26 lentil genotypes representing 4 species and 3 subspecies of Lens. Plants were grown in a greenhouse using a completely randomized design with three replicates (n=78). Seed mineral concentrations were measured using acid digestion followed by inductively coupled plasma-optical emission spectroscopy. Concentrations of Fe, Zn, Ca, Cu, and Mg in seeds varied from 26-92, 17-51, 97-536, 3-12 and 272-892 mg kg -1 , respectively, among the Lens culinaris genotypes. Mineral concentrations for L. lamottei (Fe=64-80, Zn=26-40, Ca=311-434, Cu=2-6, Mg=754-839 mg kg -1 ), L. nigricans (60-70, 33-39, 508-590, 3-4, 445-738 mg kg -1 ) and L. ervoides (65, 37, 339, 6, 638 mg kg -1 ) were within the range of Lens culinaris genotypes. No wild species was superior to cultivated ones for all micronutrients. A larger set of germplasm should be evaluated in future experiments to identify additional genetic variation in lentil for these micronutrients.

Development of a reliable GC-MS method for fatty acid profiling using direct transesterification of minimal quantities of microscopic orchid seeds

AbstractOrchid seeds are among the smallest seeds in nature and they are naturally rich in fatty acids. However, the fatty acid composition of orchid seeds has not been investigated because the sample masses utilized for widely used methods for fatty acid profiling would generally require prohibitively large numbers (i.e. 10,000s) of seeds. The present work aimed to develop a method for fatty acid analysis using gas chromatography–mass spectrometry on small quantities (mg) of seeds. The method was developed using the seeds of two species,Dactylorhiza fuchsii, a temperate terrestrial, andGrammatophyllum speciosum, a tropical epiphyte. A range of sample masses was tested to determine the minimum mass required to achieve reliable fatty acid composition data. A direct transesterification method was used, which did not require extraction of fatty acids from seeds prior to analysis, and the effects of seed processing (crushed versus intact seeds) and incubation time in toluene on fatty acid yield were tested. Stable fatty acid profiles were obtained using as little as 10 mg of seeds. Neither crushing the seeds nor extending the toluene incubation step had much effect on the fatty acid yield. The simple direct transesterification method presented will enable the fatty acid composition of orchid seeds, and possibly other small seeds, to be determined reliably for studies into seed development, storage and germination.

In vitro health beneficial activities of Pumpkin seeds from Cucurbita moschata cultivated in Lemnos

Pumpkin seeds are commonly consumed in Greece. Although Cucurbita moschata is locally grown in Lemnos and is traditionally used in pumpkin pies, the seeds are currently discarded after consumption of the fruit flesh. The aim of the present study was to investigate the nutritional functionality of pumpkin seeds from Cucurbita moschata grown in Lemnos. Cucurbita moschatas’ seeds , raw or roasted, were appropriately extracted and the results are presented for raw versus (vs) roasted seed extracts. The phenolic content was expressed as μg gallic acid/g of seeds according to Folin-Ciocalteau assay (370.3 ± 19.1 vs 551.0 ± 22.0). Antioxidant capacity was expressed as equivalent amount for 50% scavenging in mg of seeds for DPPH (50.03 ± 5.91 vs 25.82 ± 6.77) and ABTS (17.85 ± 0.77 vs 12.77 ± 0.76) assays, and as μmol of trolox/g of seeds for FRAP (1.19 ± 0.05 vs 2.50 ± 0.23) and CUPRAC (2.13 ±0.11 vs 3.25 ± 0.06) assays. Anti-inflammatory/anti-thrombotic and anti-diabetic activities were expressed as mg of seeds for 50% inhibition of platelet activating factor (0.62 vs 0.15) and as μg of seeds for 25% inhibition of alpha-glycosidase (40.0 vs 61.0) activities respectively. Moreover, anti-atherogenic activity was expressed as the % increase in lag time of human plasma oxidation (62.7 versus 163.2) Raw and roasted pumpkin seed extracts exert anti-oxidant, anti-thrombotic/anti-inflammatory, anti-atherogenic and antidiabetic activities. Cucurbita moschata seeds may represent a novel opportunity for development of functional foods, with a local interest in Lemnos that would contribute also to the regional public health improvement.

In vitro health beneficial activities of Pumpkin seeds from Cucurbita moschata cultivated in Lemnos

Pumpkin seeds are commonly consumed in Greece. Although Cucurbita moschata is locally grown in Lemnos and is traditionally used in pumpkin pies, the seeds are currently discarded after consumption of the fruit flesh. The aim of the present study was to investigate the nutritional functionality of pumpkin seeds from Cucurbita moschata grown in Lemnos.Cucurbita moschatas’ seeds, raw or roasted, were appropriately extracted and the results are presented for raw versus (vs) roasted seed extracts. The phenolic content was expressed as μg gallic acid/g of seeds according to Folin-Ciocalteau assay (370.3 ± 19.1 vs 551.0 ± 22.0). Antioxidant capacity was expressed as equivalent amount for 50% scavenging in mg of seeds for DPPH (50.03 ± 5.91 vs 25.82 ± 6.77) and ABTS (17.85 ± 0.77 vs 12.77 ± 0.76) assays, and as μmol of trolox/g of seeds for FRAP (1.19 ± 0.05 vs 2.50 ± 0.23) and CUPRAC (2.13 ±0.11 vs 3.25 ± 0.06) assays. Anti-inflammatory/anti-thrombotic and anti-diabetic activities were expressed as mg of seeds for 50% inhibition of platelet activating factor (0.62 vs 0.15) and as μg of seeds for 25% inhibition of alpha-glycosidase (40.0 vs 61.0) activities respectively. Moreover, anti-atherogenic activity was expressed as the % increase in lag time of human plasma oxidation (62.7 versus 163.2)Raw and roasted pumpkin seed extracts exert anti-oxidant, anti-thrombotic/anti-inflammatory, anti-atherogenic and antidiabetic activities. Cucurbita moschata seeds may represent a novel opportunity for development of functional foods, with a local interest in Lemnos that would contribute also to the regional public health improvement.

First Report of Race Composition and Distribution of Sunflower Broomrape, Orobanche cumana, in China.

Sunflower broomrape (Orobanche cumana Wallr.) is a holoparasitic plant that penetrates the vascular system of sunflower roots, absorbs plant nutrients and water, and thus causes stunting, reduced growth, and severe yield losses (3). To date, seven races of sunflower broomrape (O. cumana) have been identified by using international standard race differential hosts in Bulgaria, Serbia, Romania, Turkey, and Russia (4). However, the race types present in China are unknown. To identify the race composition of sunflower broomrape in China, race differential hosts of sunflower broomrape were received from Dr. Dragan Skoric (Serbian Academy of Sciences and Arts, Novi Sad, Serbia): Line AD66 has no resistant genes; Kruglik-41 contains resistant gene Or1; B-RO-02A has Or2; Record has Or3; LC1002B has Or4; LC1003B has Or5; LC-1093 has Or6, and Race-G-2 has Or7 (1). Eighteen sunflower broomrape samples were collected in August of 2011, 2012, and 2013 from different provinces/locations in China, including Xinjiang (Xinyuan, Shihezi, Tekesi, Beitun, Urumqi, and Yining), Inner Mongolia (Linhe, Xixiaozhao, Wuqianqi, Tuzuoqi, Keyouqianqi, and Aohanqi), Shanxi (Hunyuan, Shilou, Mizhi, and Dingbian), Jilin (Tongyu), and Hebei (Xuanhua). The differential hosts were each inoculated with the seeds of each broomrape isolate that was recovered, as described by Pancenko with minor modification (2). Briefly, two parts of field soil and one part of vermiculite were mixed together and used as potting mix. The mix was inoculated with broomrape seeds at 10 mg of seeds per 100 g of potting mix. The inoculated mix was placed in a 7-cm (diameter) × 11-cm (height) plastic pot to fill two-thirds of the pot volume. Three sunflower seeds were placed on the surface of the mix at an even distance from each other and covered with additional mix. The pots were kept in a greenhouse under a 16-h photoperiod at 10,000 lux of illumination intensity, temperature of 20-25°C, and 40% relative humidity. Forty days after incubation, sunflower seedlings were taken out from the pot and the roots washed with tap water. The number of tubercles was recorded on the root of each differential host. Race types were determined based on the reaction (tubercule formation on roots) of all the standard differential hosts to the test isolate. The results showed that races A, D, E, and G of O. cumana were present among the isolates. Race G was found in Wuqianqi, Xixiaozhao, and Linhe in the western part of Inner Mongolia. Race E was found only in Shihezi of Xinjiang. Race D was found in Aohanqi and Keyouqianqi (eastern part of Inner Mongolia); Xinyuan, Tekesi, Beitun, and Urumqi (northern part of Xinjiang); and Tongyu (northern part of Jilin). Race A was found in Mizhi, Shilou, and Hunyuan of Shanxi province and Xuanhua in Hebei province. Additionally, race A was also found in Tuzuoqi, the middle region of Inner Mongolia. Thus, races A, D, E, and G were the main race types of O. cumana in China. Race D was the predominant race type and had the widest distribution. Race G was the highest level race type in this study but was mainly limited to the western part of Inner Mongolia. This is the first report of race composition and distribution of sunflower broomrape (O. cumana) in China.

Hexadecyltrimethylammonium Bromide (CTAB)-based Protocol to Isolate High-Quality RNA in Adequate Quantities for Gene Expression Analyses in Developing Seeds of Lentils (Lens culinaris Medik.)

RNA isolation from polysaccharide- and phenolics-rich plant tissues such as developing lentil (Lens culinaris Medik.) seeds is challenging. High-quality RNA is needed in adequate quantities for transcriptome analysis to study seed quality traits. To date, a suitable method to isolate high-quality and -quantity RNA from lentil seeds has not been reported. The objective of this study was to develop a simple and reproducible method to isolate high-quantity and -quality RNA from developing lentil seeds for gene expression analysis. Methods based on Trizol™ reagents and phenol:guanidine gave low yields of RNA. A method based on hexadecyltrimethylammonium bromide followed by a lithium chloride precipitation yielded RNA in high quantity (210–260 µg from 200 mg of seeds) and quality (A260/280 ratio of about 2.2). Isolated RNA was used to study the expression of the granule-bound starch synthase I (GbssI) during lentil seed development by RNA gel blot and quantitative real-time polymerase chain reaction. The expression pattern of the GbssI was similar to that reported for pea GbssI gene.

The metabolism of ageing seeds: changes in the raffinose family oligosaccharides during storage of field bean (Vicia faba var. minor Harz) seeds

Seeds of field bean cv. Nadwiślański harvested in 1980, 1986 and 1992 were studied. Results of investigations showed that the four analysed sugars (saccharine, verbascose, raffinose and stachyose) made up from 60.1 mg of 1 g dry matter of seeds harvested in 1992 to 67 mg of seeds collected in 1986. After three years of storage in laboratory conditions we observed a decline of the amount of these oligosaccharides. The saccharose:raffinose family oligosaccharides ratio grows with the seed age.

Variation of major minerals and trace elements in seeds of tartary buckwheat (Fagopyrum tataricum Gaertn.)

Tartary buckwheat (Fagopyrum tataricum Gaertn.) contains protein of high nutritional value, polyphenols, vitamins and minerals. It is one of the most important minor crops in China and has a great potential as a health and functional food. However, information on the elemental mineral composition of its seeds remains limited. The concentrations of Cu, Zn, Fe, K, and Mg in seeds of 123 tartary buckwheat accessions from the same cultivation were studied by means of flame atomic absorption spectrometry. The results revealed that the average concentrations of Cu (x1), Zn (x2), Fe (x3), K (x4), and Mg (x5) elements in the accessions are 19.49 (with a range of 5.74–36.01 mg/kg), 27.41 (8.44–66.63 mg/kg), 656.24 (21.8–3,990 mg/kg), 3,639.23 (1,737–5,831 mg/kg), and 1,523.89 mg/kg (729–3,104 mg/kg) respectively. Among them, Fe concentration has the highest coefficient of variation (114.7 %). The results also revealed five significant positive correlations among Cu, Zn, Fe, K, and Mg concentrations. Therefore, distinct genotypes with high concentration of mineral elements should be effective for the development of special buckwheat varieties and improvement of its food nutritional quality.

Accelerated aging of ipê seeds under controlled conditions of storage

This research was aimed at studying effects of storage and accelerated aging on germination and profile of storage proteins in Handroanthus albus seeds. These were stored into a cold chamber (± 8 ºC; RH ± 40%) and after periods of 0, 3, 6, 9, and 12 months of storage, were subjected to accelerated aging for 0, 24, 48, 72, and 96 hours. Relationships between germination and proteins profile were assessed. Germination test was performed at 25 ºC, under constant light. For protein extraction, 125 mg of seeds were macerated in 2 mL of extraction buffer (1M Tris-HCl; pH 8.8) and applied to SDS-PAGE polyacrylamide gel at 80 V .15 h-1. Twelve month storage, combined with 72 hours accelerated aging have increased germination in approximately 65% when compared to non-aged seeds or to seeds with 24 h of accelerated aging. Besides beneficial effects, degradation and synthesis of different proteins were observed. It was concluded that germination of Handroanthus albus seeds, when not subjected to accelerated aging, is favored by storage in cold chamber during three to six months, or from nine to 12 months when subjected to accelerated aging process. Storage proteins may be associated to those increases, and hence further studies are needed.

Metabolic Engineering of ω3-Very Long Chain Polyunsaturated Fatty Acid Production by an Exclusively Acyl-CoA-dependent Pathway

omega3-Very long chain polyunsaturated fatty acids (VLCPUFA) are essential for human development and brain function and, thus, are indispensable components of the human diet. The current main source of VLCPUFAs is represented by ocean fish stocks, which are in severe decline, and the development of alternative, sustainable sources of VLCPUFAs is urgently required. Our research aims at exploiting the powerful infrastructure available for the large scale culture of oilseed crops, such as rapeseed, to produce VLCPUFAs such as eicosapentaenoic acid in transgenic plants. VLCPUFA biosynthesis requires repeated desaturation and repeated elongation of long chain fatty acid substrates. In previous experiments the production of eicosapentaenoic acid in transgenic plants was found to be limited by an unexpected bottleneck represented by the acyl exchange between the site of desaturation, endoplasmic reticulum-associated phospholipids, and the site of elongation, the cytosolic acyl-CoA pool. Here we report on the establishment of a coordinated, exclusively acyl-CoA-dependent pathway, which avoids the rate-limiting transesterification steps between the acyl lipids and the acyl-CoA pool during VLCPUFA biosynthesis. The pathway is defined by previously uncharacterized enzymes, encoded by cDNAs isolated from the microalga Mantoniella squamata. The conceptual enzymatic pathway was established and characterized first in yeast to provide proof-of-concept data for its feasibility and subsequently in seeds of Arabidopsis thaliana. The comparison of the acyl-CoA-dependent pathway with the known lipid-linked pathway for VLCPUFA biosynthesis showed that the acyl-CoA-dependent pathway circumvents the bottleneck of switching the Delta6-desaturated fatty acids between lipids and acyl-CoA in Arabidopsis seeds.

A Temperature-sensitive Mutation in the Arabidopsis thaliana Phosphomannomutase Gene Disrupts Protein Glycosylation and Triggers Cell Death

Eukaryotic phosphomannomutases (PMMs) catalyze the interconversion of mannose 6-phosphate to mannose 1-phosphate and are essential to the biosynthesis of GDP-mannose. As such, plant PMMs are involved in ascorbic acid (AsA) biosynthesis and N-glycosylation. We report on the conditional phenotype of the temperature-sensitive Arabidopsis thaliana pmm-12 mutant. Mutant seedlings were phenotypically similar to wild type seedlings when grown at 16-18 degrees C but died within several days after transfer to 28 degrees C. This phenotype was observed throughout both vegetative and reproductive development. Protein extracts derived from pmm-12 plants had lower PMM protein and enzyme activity levels. In vitro biochemical analysis of recombinant proteins showed that the mutant PMM protein was compromised in its catalytic efficiency (K cat/K m). Despite significantly decreased AsA levels in pmm-12 plants, AsA deficiency could not account for the observed phenotype. Since, at restrictive temperature, total glycoprotein patterns were altered and glycosylation of protein-disulfide isomerase was perturbed, we propose that a deficiency in protein glycosylation is responsible for the observed cell death phenotype.

The Mechanism of Ammonium Phosphate Injury to Seeds

Cotton and wheat seeds were soaked in various salt solutions (including ammonium phosphates). The seeds were then allowed to germinate. With increasing salt concentration, the germination of cotton did not decrease, whereas the germination of wheat decreased in most cases. Soaking cotton seeds in 0.25m (NH4)2SO4 solutions adjusted to pH levels between 7.2 and 9.0 showed germination injury above pH 7.8. The harmful effect of diammonium phosphate treatment was largely alleviated by subsequent soaking of seeds in dilute solutions of MgSO4. Germination injury from (NH4)2HPO4 appeared to be largely due to the inactivation of Mg in seeds.