The Dry Storage of Citrus Seeds

The survival of seeds of lemon (Citrus limon L.), lime [C. arantifolia(Christm.) Swing.] and sour orange (C. aurantium L.) was examinedunder a wide range of constant moisture contents and temperatures.Seed longevity was increased by decreasing the moisture contentand temperature of the storage environment. Maximum viabilitywas maintained in the combination of storage conditions includingthe lowest moisture content (5 per cent) and lowest temperature(–20 °C) investigated. The practicality of dry storageof citrus seed for genetic conservation is discussed. Citrus limon L., lemon, Citrus aurantifolia (Christm.), Swing, lime, Citrus aurantium L., sour orange, dry storage, moisture content, temperature, seed viability, seed longevity     

Root and tuber phytoliths and starch grains document manioc (Manihot esculenta) arrowroot (Maranta arundinacea) and llerén (Calathea sp.) at the real alto site Ecuador

Although roots and tubers are dietary staples in many parts of the world, their use is difficult to document archaeo logically because their organic remains are often poorly preserved in archaeological sedi ments. Here we describe the first diagnostic phytoliths from the underground storage organs of the important New World agricultural crops manioc or yuca(Manihot esculenta Crantz), arrowroot(Maranta arundinacea L.), and llerén(Calathea allouia [Aubl.] Lindl.) and demonstrate their usefulness for identifying prehistoric root and tuber processing with a study of stone artifacts from a Valdivia 3 (2800–2400 B.C., calibrated) household at Real Alto, Ecuador. Gelatinized starch (heat-altered) and unaltered starch from maize (Zea mays L.), arrowroot, and manioc were also found on these stone tools. Our data document early evidence for manioc in Ecuador’s coastal lowlands. In combination, these phytoliths and starch residues provide evidence that both raw and cooked foods were processed in this early mixed agricultural economy.     

Lipases in the storage tissues of peanut and other oil seeds during germination

The castor-bean endosperm-the best-studied material of reserve lipid hydrolysis in seed germination-was previously shown to have an acid lipase and an alkaline lipase having reciprocal patterns of development during germination. We studied oil seeds from 7 species, namely castor bean (Ricinus communis L.), peanut (Arachis hypogaea L.), sunflower (Helianthus annus L.), cucumber (Cucumis sativus L.), cotton (Gossypisum hirsutum L.), corn (Zea mays. L.) and tomato (Lycopersicon esculentum Mill.). The storage tissues of all these oil seeds except castor bean contained only alkaline lipase activity which increased drastically during germination. The pattern of acid and alkaline lipases in castor bean does not seem to be common in other oil seeds. The alkaline lipase of peanut cotyledons was chosen for further study. On sucrose gradient centrifugation of cotyledon homogenate from 3-d-old seedlings, about 60% of the activity of the enzyme was found to be associated with the glyoxysomes, 15% with the mitochondria, and 25% with a membrane fraction at a density of 1.12 g cm^-3. The glyoxysomal lipase was associated with the organelle membrane, and hydrolyzed only monoglyceride whereas the mitochondrial and membrane-fraction enzymes degraded mono-, di- and triglycerides equally well. Thus, although the lipase in the glyoxysomes had the highest activity, it had to cooperate with lipases in other cellular compartments for the complete hydrolysis of reserve triglycerides.     

Inhibition of germination and α-amylase induction by 6-methoxy-2-benzoxazolinone in twelve plant species

6-Methoxy-2-benzoxazolinone (MBOA) inhibited germination of rice (Oryza sativa L.), wheat (Triticum aethiopicum Jakubz), rye (Secale cereale L.), onion (Allium cepa L.), wild oat (Avena fatua L.), barnyard grass [Echinochloa crus-galli (L.) Beauv.], ryegrass (Lolium rigidum Gaudin), cress (Lepidium sativum L.), lettuce (Lactuca sativa L.), tomato (Lycopersicum esculentum Mill.), carrot (Daucus carota L.) and amaranth (Amaranthus retroflexus L) and the inhibition increased with increasing MBOA concentrations. MBOA also inhibited the induction of α-amylase in these plant seeds and the inhibition increased with increasing MBOA concentrations. There were variations in sensitivity of these plant species to MBOA, and species of family Poaceae (barnyard grass, wild oat, rice, rye, ryegrass, and wheat) were less sensitive to MBOA than the other plant species.     

Effects of crop rotation and fertilization on catalase activity in a soil of the southeastern United States

Summary Catalase activity of a loamy sand under a 3-year crop rotation in the southeastern U.S.A. was monitored. Corn (Zea mays L.), cotton (Gossypium hirsutum L.), and soybean [Glycine max (L.) Merr.] were the summer crops in the rotation. Winter wheat (Triticum aestivum L.) was planted after corn, and soybean was followed by a winter fallow period. Cotton was followed by a mixture of common vetch (Vicia sativa L.) and crimson clover (Trifolium incarnatum Gibelli & Belli) which was eventually plow-incorporated as a green manure. Highest mean catalase activities were recorded in soil under the wheat, soybean, and winter legume crops; lowest activities were found in soil bearing corn and cotton, and during the winter fallow period. The fertilization regime influenced soil catalase activity independently of the crop. Soil deficient in any of the major elements showed low enzyme activity. Highest activity was found in soil fertilized with P and K, and with N supplied by a winter legume crop. Addition of supplementary mineral nitrogen to this regime reduced catalase activity. Elimination of the winter legume crop from an otherwise complete fertilization regime resulted in a drastic reduction in enzyme activity. In soil receiving a complete fertilization regime there was a close correlation between soil catalase and xylanase activities. A similar correlation between these two enzymes was not found in soil receiving incomplete fertilization.     

Recent advances in breeding for improving iron utilization by plants

Iron-chlorosis deficiency may occur when an iron-inefficient genotype is grown on calcareous soil. One way to correct the problem is to modify the genotype by plant breeding. Cultivars have been released for oat (Avena byzantina C. Koch), sorghum [Sorghum bicolor (L.) Moench], dry bean (Phaseoulus vulgaris L.), and soybean [Glycine max (L.) Merr.]. Progress is being made in peanut (Arachis hypogea L.), forage species such as clovers (Trifolium sp.) and bluestems (Botriochloa sp.), and pepper (Capsicum annuum L.). Screening of rootstocks is done on citrus (Citrus sp.), mango (Manguifera indica L.), and avocado (Persea americana Mill.).     

The content of N-acylphosphatidylethanolamines in the seeds of cultivated plants and grain products

The content of the minor class of phospholipids, N-acylphosphatidylethanolamines (NAPEs) in mature seeds of cultivated plants: kidney bean (Phaseolus vulgaris L.), soybean (Glycine max (L.) Merr.), soft spring wheat (Triticum aestivum L. emend. Fiori et Paol), barley (Hordeum vulgare L.), and oat (Avena sativa L.), and the products of technological processing of grain cultures (floor, bran) was studied. Reliable NAPE identification was performed by a comparison of their chromatographic mobility with the marker NAPE sample from wheat flour and synthetic phosphatidylmethanol, and also using specific reagents. Kidney bean cv. Shchedraya seeds contained the highest amount of NAPEs. In legumes, the content of NAPEs varied not only in different species but also in different cultivars of a single species. In cereals, the highest NAPE content was detected in the barley seeds and best quality wheat flour. The content of NAPEs in cereal seeds was less variable than in legumes. NAPE quantification showed that accumulation of this phospholipid class occurred in parallel with accumulation of total phospholipids in seeds. The relation between NAPE content and the processes of seed development and their lipid composition is discussed. The seeds and products best suitable for NAPE isolation are recommended.     

Seed growth rate in grain legumes I. Effect of photoassimilate availability on seed growth rate

The dry weight of harvested grain legume seeds is strongly related to their growth rate during the period of storage accumulation in the cotyledons, which begins approximately at the end of embryo cell division. Depodding, defoliation, shading or changes in air CO2 concentration were applied during seed filling (i.e. during the decrease in seed water concentration) to field and glasshouse-grown plants, in order to affect the source-sink ratio. The experiments involved three legume species, namely pea (Pisum sativum L.), soybean (Glycine max L. Merr.) and white lupin (Lupinus albus L.). Some treatments affected the number of abortions of less developed seeds from younger pods, but they did not significantly affect the number or the growth rate of filling seeds, demonstrating the priority of carbohydrate partitioning to filling seeds. The maximum growth rate of seeds was achieved regardless of the intra-plant competition level, and the duration of seed growth was shortened if the photosynthetic activity was not sufficient to fulfil the assimilate demand of filling seeds.     

Effect of industrial air pollution on wild plant seed germination and seedling growth

Germination of the following wild plant seeds was studied: bilberry (Vaccinium myrtillus L.), cowberry (V. vitis-idaea L.), bog bilberry (V. uliginosum L.), black crowberry (Empetrum hermaphroditum Hagerup), bearberry (Arctostaphylos uva-ursi (L.) Spreng.), bunchberry (Chamaepericlymenum suecicum (L.) Aschers. et Graebn.), cottongrass (Eriophorum polystachion L.), goldenrod (Solidago lapponica With.), fireweed (Chamaenerion angustifolium (L.) Scop.), marsh cinquefoil (Comarum palustre L.), cloudberry (Rubus chamaemorus L.), and Scots pine (Pinus sylvestris L.). The seeds were collected at different distances from the source of industrial air pollution (Severonickel smelter complex, Murmansk region). The task was the assessment of potential possibility of restoring corrupted north forest plant communities via seed propagation. By the response of reproductive structures to stressor, investigated species were divided into 3 groups: tolerant (members of the genus Vaccinium and Ch. angustifolium); moderately tolerant (C. palustre, E. polystachion, A. uva-ursi, and R. chamaemorus); and sensitive (P. sylvestris, E. hermaphroditum, and S. lapponica). Laboratory seed germinability of Vaccinium species was high (> 90%) regardless of the levels of Ni and Cu accumulation in the seeds and the index of technogenic load, whereas this index in E. hermaphroditum and P. sylvestris seeds was significantly reduced with the increase in the heavy metal contents in the seeds. The greenhouse experiments with the seeds of three Vaccinium species collected in the background area and in the zone of the highest pollution and germinated on the forest litter from the same sites and observation for seedling development allow us to conclude that a potential possibility of these species to seed propagation are not limited by their seed viability even under conditions of the highest technogenic load. In sites of environment pollution, the high metal content in the upper soil layer is the main factor limiting plant seed propagation.     

Influence of paddy and corn in different rotations on wheat yield,nutrient removal and soil properties

Summary In a 3 year field study, the effect of two rotations, paddy (Oryza sativa L.), wheat (Triticum aestivum L.), mung (Phaseolus aureus L.) and corn (Zea mays L.), wheat (Triticum aestivum L.), mung (Phaseolus aureus L.) on wheat yield and chemical, physical and biological properties of soil was evaluated. Grain yield of the wheat sown after paddy during 1972–73, 1973–74 and 1974–75 was lesser by 0,300 and 390 kg/ha respectively than that of the wheat following corn. The reduction in the yield of wheat was attributed to relatively higher NPK removal by paddy, greater immobilization of N applied to wheat and deterioration of soil physical conditions in the paddy field. Total NPK removal by paddy average 131 kg/ha more than that by corn. Sharp increase in bacterial population of soil during early growth of wheat that followed paddy and the concurrent less available N in soil and low N content in wheat plants suggested that the N applied to wheat was immobilised to organic form. The increase in soil bulk density and particle dispersion ratio and decrease in water storage in deeper soil layers in the paddy field probably restricted the root proliferation and growth of wheat.     

The expression of dehydrin proteins in desiccation-sensitive (recalcitrant) seeds of temperate trees

Proteins that have homology with dehydrins have been identified immunologically in the desiccationsensitive (recalcitrant) seeds of English oak (Quercus robur L.), European chestnut (Castanea sativa L.), horse chestnut (Aesculus hippocastanum L.), sycamore (Acer psuedoplatanus L.) and silver maple (Acer saccharinum L.), and in the desiccation-tolerant seeds of Norway maple (Acer platanoides L.). The mRNA for a late embryogenesis abundant (LEA) protein (dehydrin) was also detected by Northern blotting, using a cDNA clone (D11) from cotton embryos, in the recalcitrant and orthodox seeds. Medium-stringency washing was required to detect this hybridization. InQ. robur the amount of dehydrin protein increased during seed development, andLEA mRNA was induced by limited desiccation and by abscisic acid. Confirmation of the presence of dehydrin mRNA in matureQ. robur andC. sativa seeds was obtained by in-vitro translation of the extracted polyadenylated RNA followed by analysis of the immunoprecipitation products. Thus the presence of dehydrin proteins is not sufficient to confer desiccation tolerance on truly recalcitrant seeds, nor can their presence or absence be used as clear criteria for identification of recalcitrant seeds.     

Growth inhibitory effect of peel extract from Citrus junos

Extract from yuzu fruit peel (Citrus junos Sieb. ex Tanaka) strongly suppressed the germination of lettuce seeds while that from the peel of other citrus fruits such as navel orange (C. sinensis) and lemon (C. limon Burm. f.) had very little or no effect. The highest inhibitory activity was located in the peel followed by the segment but no significant activity was found in the seed extract of yuzu fruit. The effect of yuzu peel extract was tested on a variety of major crops including 38 crop species. Germination of seeds of tomato (Lycopersicon esculentum Mill.), celery (Apium graveolens L. var. dulce) and watercress (Nasturtium officinale R. Br.) was completely blocked by 27.8 mg dry peel equivalent ml^–1 of yuzu peel extract, while that of cucumber (Cucumis sativus L.) and pumpkin (Cucurbita moschata [Duch. ex Lam.] Duch. ex Poir.) seeds was not affected at this concentration, showing a broad variation in the sensitivity of crop seeds to the extract. The effectiveness of yuzu peel was also tested on some harmful weeds. The extract inhibited the elongation of both radicle and hypocotyl in summer weed quinoa (Chenopodium quinoa) grown on agar plates. Yuzu peel powder added to the soil was also effective in suppressing the growth of C. quinoa, Sonchus oleraceus L. and Digitaria ciliaris, while it had little effect on the spring weed Alopecurus aequalis Sobol. A strong growth inhibitory activity of yuzu peel was found in the aqueous phase after solvent extraction and most of the activity was recovered in the neutral fraction that passed through cation and anion exchange resins.     

Oviposition and development response of perilla seed bugs (Nysius sp.) (Heteroptera: Lygaeidae) to five crop seeds

The perilla seed bugs, Nysius plebeius Distant and Nysius hidakai Nakatani, are emerging pests of perilla crop in Korea. Here, we investigated the life-history variables of N. plebeius and N. hidakai on five commonly grown crop seeds: perilla [Perilla frutescens (L.) Britt.], sesame (Sesamum indicum L.), sorghum [Sorghum bicolor (L.)], proso millet (Panicum miliaceum L.) and foxtail millet (Setaria italic L.). Bug oviposition, total developmental period, adult emergence, adult longevity and adult weight of both Nysius species were determined in both choice and no-choice tests. The oviposition and development periods of N. plebeius and N. hidakai varied significantly among seed species. The most preferred seed species for oviposition were perilla seeds, followed by sesame, sorghum and foxtail millet, whereas proso millet seeds were the least preferred. The bugs development period was faster in perilla seeds, with higher adult emergence, greater adult longevity and heavier adult weight. The higher oviposition preference and faster development with longer longevity of both Nysius species on perilla seeds is probably due to the physicochemical and nutritional attributes of the seeds. This information may enable the exploration of resistant genetic materials and chemical traits associated with seeds for breeding programme. Further, the outcomes of this study are discussed in terms of bug's behavioural response to crop seeds and management strategy of Nysius species as alternative to chemical management.     

Evolutionary history of two endemic Appalachian conifers revealed using microsatellite markers

Fraser fir (Abies fraseri [Pursh] Poir.) and intermediate fir (Abies balsamea [L.] Mill. var. phanerolepis Fern.) exist in small populations in the Appalachian highlands of the southeastern United States. We used ten nuclear microsatellite markers to quantify genetic variation within Fraser fir and intermediate fir, and to examine their evolutionary relationships with the widespread balsam fir (Abies balsamea [L.] Mill.). We found little genetic differentiation among these taxa, suggesting that Fraser fir might best be classified as a variety of balsam fir. The results further appear to reject the hypothesis that intermediate fir was of hybrid origin between two comparatively distantly related species. Low levels of genetic diversity suggest that intermediate fir and Fraser fir have undergone at least some genetic degradation since post-Pleistocene isolation. The results may prove important for in situ and ex situ gene conservation efforts for Fraser fir and intermediate fir, which are imperiled by an exotic insect and by global climate change.     

Responses of Tribolium castaneum to olfactory cues from cotton seeds,the fungi associated with cotton seeds,and cereals

We tested, in an olfactometer, whether or not Tribolium castaneum Herbst (Coleoptera: Tenebrionidae) responds preferentially to the volatiles that emanate from the fungi associated with cotton [Gossypium hirsutum L. (Malvaceae)] seed over those that emanate from cereals, because cereals are usually portrayed as the primary resources of these beetles. Pairwise comparisons were conducted between cotton seed, wheat (Triticum aestivum L.), and sorghum [Sorghum bicolor (L.) Moench] (both Poaceae); volatiles were tested from intact seeds and from both water and ethanol extracts. The results demonstrate that T. castaneum is attracted more strongly to cotton seeds with its lint contaminated with fungi, than to the conventional resources of this species (i.e., wheat and sorghum). Further tests prove that it is the fungus on the lint that produces the active volatiles, because the beetles did not respond to sterilized cotton lint (i.e., without the fungi typically associated with it when cotton seed is stored). Tests with five fungal cultures (each representing an unidentified species that was isolated from the field‐collected cotton lint) were variable across the cultures, with only one of them being significantly attractive to the beetles. The others were not attractive and one may even have repulsed the beetles. The results are consistent with the beetles having a strong ecological association with fungi and suggest it would be worth investigating the ecology of T. castaneum from this perspective.     

Functional analyses of TaHMA2, a P1B‐type ATPase in wheat

Currently, there are few studies concerning the function of heavy metal ATPase 2 (HMA2), particularly in monocotyledons, and the potential application of this protein in biofortification and phytoremediation. Thus, we isolated and characterized the TaHMA2 gene from wheat (Triticum aestivum L.). Our results indicate that TaHMA2 is localized to the plasma membrane and stably expressed, except in the nodes, which showed relatively high expression. Zinc/cadmium (Zn/Cd) resistance was observed in TaHMA2‐transformed yeast. The over‐expression of TaHMA2 increased the elongation and decreased the seed‐setting rate in rice (Oryza sativa L.), but not Arabidopsis thaliana, tobacco (Nicotiana tabacum L.) or wheat. TaHMA2 over‐expression also improved root‐shoot Zn/Cd translocation, especially in rice. The seeds of transgenic rice and wheat, not tobacco, showed decreased Zn concentrations. The Zn concentration was decreased in all parts of the transgenic rice seeds, but was decreased only in the ventral endosperm of wheat, which showed an increased Zn concentration in the embryo and aleurone. The over‐expression of TaHMA2 improved plant tolerance under moderate Zn stress and Zn deficiency, but Zn and Cd resistance decreased under high levels of Zn and Cd stress, respectively. The Cd concentration in transgenic rice seedlings was dramatically increased under Zn deficiency. Thus, over‐expression of TaHMA2 showed a more obvious phenotype in monocotyledons than in dicotyledons. These findings provide important information for TaHMA2, and more efforts should be made in the future to characterize the reduced Zn concentration in TaHMA2 transgenic grains and the diversity of TaHMA2 substrate specificity.     

Visualisation of stromules in transgenic wheat expressing a plastid-targeted yellow fluorescent protein

Stromules are stroma-filled tubules that extend from the plastids in all multicellular plants examined to date. To facilitate the visualisation of stromules on different plastid types in various tissues of bread wheat (Triticum aestivum L.), a chimeric gene construct encoding enhanced yellow fluorescent protein (EYFP) targeted to plastids with the transit peptide of wheat granule-bound starch synthase I was introduced by Agrobacterium-mediated transformation. The gene construct was under the control of the rice Actin1 promoter, and EYFP fluorescence was detected in plastids in all cell types throughout the transgenic plants. Stromules were observed on all plastid types, although the stromule length and abundance varied markedly in different tissues. The longest stromules (up to 40 μm) were observed in epidermal cells of leaves, whereas only short beak-like stromules were observed on chloroplasts in mesophyll cells. Epidermal cells in leaves and roots contained the highest proportion of plastids with stromules, and stromules were also abundant on amyloplasts in the endosperm tissue of developing seeds. The general features of stromule morphology and distribution were similar to those shown previously for tobacco (Nicotiana tabacum L.) and arabidopsis (Arabidopsis thaliana (L.) Heynh.).     

Immunodetection and immunolocalization of tryptophanins in oat (Avena sativa L.) seeds

Tryptophanins (TRPs) are low molecular weight, tryptophan-rich, basic proteins found in oat (Avena sativa L.) seeds. Like their counterpart puroindolines (PINs) from wheat (Triticum aestivum L.), TRPs are thought to be involved in flour softness as well as disease resistance against phytopathogenic fungi. PINs are known to be the major components of ‘friabilin’ associated with the surface of water washed starch grains and possess lipid binding properties. Two polyclonal antisera against puroindoline-a (PIN-a), and puroindoline-b (PIN-b) respectively; and a monoclonal antiserum raised against ‘friabilin’ were used as primary antibodies in immunoblotting experiments. All antisera detected immunoreactive polypeptides, with approximate relative masses of 15–16 kDa, in oat, wheat, and barley (Hordeum vulgare L.) seed extracts but not in rice (Oryza sativa L.), maize (Zea mays L.), bean (Phaseolus vulgaris L.), pea (Pisum sativum L.) and lentil (Lens culinaris Medic.) seed extracts. Immunoreactive polypeptides were detected in aqueous ethanol [52% (v/v) ethanol] seed extracts. Both anti-‘friabilin’ monoclonal and anti-PIN-b polyclonal antisera recognized 15 as well as 16 kDa tryptophanins in oat seeds from different cultivars. On the other hand, anti-PIN-a polyclonal antiserum strongly cross-reacted with 16 kDa TRP and weakly with 15 kDa TRP. Tryptophanins were found to be associated with the surface of starch grains in oat endosperm tissue using both fluorescence and confocal laser scanning microscopies with anti-‘friabilin’ monoclonal antiserum. SDS-PAGE and immunoblotting assays revealed a gradual synthesis of TRPs as early as milk stage in developing oat seeds. On the other hand, TRPs tend to undergo degradation during seed germination.     

Optimizing Seed Water Content: Relevance to Storage Stability and Molecular Mobility

This research was conducted to determine the optimum moisture content (MC) that gave maximum longevity to seeds. Three species were used to represent seeds with different dry matter reserves, which gives them different sorption properties: maize (Zea mays L.), elm (Ulmus pumila L.) and safflower (Carthamus tinctorius L.). The seeds of elm, safflower, and maize embryos with MC ranging from 0.00–0.15 g H₂O/g dry weight (DW) were stored at 35 °C for different periods of time. The results showed that the optimum MC for seed and embryo storage varied between species (0.057 g H₂O/g DW for maize embryos, 0.045 g H₂O/g DW for elm, and 0.02 g H₂O/g DW for safflower). Drying below this optimum MC increased the aging rate and there were detrimental effects of drying. The relative humidity corresponding to optimum MC in embryos of maize, elms and safflower was about 15%, 12% and 7% respectively, according to the lipid composition of the embryos. The data provided confirmatory evidence that molecular mobility (ΔAzz) in elms, maize and safflower embryos was compatible with the optimum moisture content.