Changes in Sugar Content during Cold Acclimation and Deacclimation of Cabbage Seedlings

The relationship between freezing tolerance and sugar contentin cabbage seedlings was investigated. Seedlings exposed tonon-freezing low temperature (5 °C) acquired freezing tolerancedown to -6 °C. The degree of freezing tolerance increasedwith duration of exposure to low temperature (up to 10 d). Sucrose,glucose, fructose and myo -inositol were detected as solublesugars in cabbage leaves, and all soluble sugars, except formyo -inositol, and starch increased gradually during cold acclimationsuch that their levels were positively correlated with the degreeof freezing tolerance. The induced freezing tolerance was attributednot to ontogenetic changes but to cold acclimation. However,the induced freezing tolerance was lost after only 1 d of deacclimationat control temperatures, and this change was associated witha large reduction in sugar content. These results reveal that the sugar content of cabbage leavesis positively correlated with freezing tolerance. Brassica oleracea L.; cabbage; cold acclimation; deacclimation; freezing tolerance; sugars     

Characterization of microsatellite loci for a barrenwort species (Epimedium diphyllum,Berberidaceae)

Microsatellites were identified and characterized from Epimedium diphyllum, a species of barrenworts, both attractive garden plants and valuable medicinal plants. Some Japanese species of Epimedium are threatened with extinction, and are listed in the Red Data Book of plants in Japan. Natural hybrid zones also have been reported among some taxa of Japanese Epimedium. We developed eight polymorphic microsatellite primers for population genetic analyses of E. diphyllum. The numbers of alleles per locus ranged from 10 to 20, with observed levels of heterozygosity between 0.85 and 1.00. These primer sets yielded amplification in the other three Japanese Epimedium. These markers will be valuable for conservation genetics, evolutionary biology, pharmacognostic study, and horticultural study of Epimedium.     

小麦根愈伤组织胚胎发育过程研究

实验通过对６个人工合成小麦品系和对照品种“中国春”种子根愈伤组织分化形成再生植株的过程进行形态和组织切片观察,发现分化初期有２种途径,一种是从愈伤组织先形成不定胚,然后再发育成不定芽和不定根,另一种途径是直接从愈伤组织中分化发育成不定根和不定芽;分化后期不定芽和不定根生长发育有３种类型：一种是不定芽发育先于不定根,一种是不定芽与不定期不定芽和不定根生长发育有种类型：一种是不一定芽发育先于不定根,一     

Alterations in the biomass-specific productivity of periphyton assemblages mediated by fish grazing

1. In an experimental flume, we examined the effects of a biomass reduction and alteration of taxonomic composition, because of grazing by the fish Plecoglossus altivelis, on the net biomass accumulation of periphyton. 2. Grazed and ungrazed assemblages with different biomass and taxonomic composition were first prepared in fish enclosures and exclosures, respectively. These assemblages were then set out in the flume and incubated for 2 days under grazing‐free conditions to examine (i) the relationship between biomass and biomass accumulation rate and (ii) the effect of taxonomic composition on the relationship between these two. 3. The grazed and ungrazed assemblages were dominated by upright filamentous cyanobacteria and diatoms, respectively. The rate of biomass accumulation decreased with increasing periphyton biomass in both the grazed and ungrazed assemblages, and was lower in the grazed than the ungrazed assemblages at any biomass level. 4. The results showed that the reduction in biomass and the alteration of taxonomic composition due to fish grazing have opposite effects on biomass‐specific productivity. Biomass accumulation rate increased in response to biomass reduction, although a shift in dominance from diatoms to upright filamentous cyanobacteria decreased the overall productivity of the periphyton.     

Consequences of scavenging behaviour in a plant bug associated with a glandular plant

To elucidate the specific associations of insects with glandular plants, the relationship between a plant bug and a wild azalea was examined. The plant bug Orthotylus gotoi Yasunaga (Hemiptera: Miridae) was found only on shrubs of Rhododendron macrosepalum Maxim. (Ericaceae) in Kyoto, central Japan. R. macrosepalum has leaves, stems, and sepals with dense stalked glands that trap and kill many arthropods. However, nymphs and adults of O. gotoi are able to move freely on R .  macrosepalum . O. gotoi frequently fed on carcasses of various arthropods trapped on R .  macrosepalum , whereas it rarely fed upon plant tissues. In laboratory experiments, O. gotoi nymphs mainly fed on the carcasses of insects, which resulted in enhanced rates of growth and metamorphosis, and adult O. gotoi lived longer when they were provided with insect carcasses. These observations and experiments suggest that O. gotoi is a scavenger. Therefore, if O. gotoi mainly feeds on carcasses of arthropods, this may result in a specific dependence on the glandular plant.  © 2006 The Linnean Society of London, Biological Journal of the Linnean Society , 2006, 88 , 593–602.     

Effects of Salt Stress on Adenine and Uridine Nucleotide Pools, Sugar and Acid-Soluble Phosphate in Shoots of Pepper and Safflower

Nieman, R. H., Clark, R. A., Pap, D., Ogata, G. and Maas, E.V. 1988. Effects of salt stress on adenine and uridine nucleotidepools, sugar and acid-soluble phosphate in shoots of pepperand safflower.-J. exp. Bot. 39: 301–309. Pepper (Capsicum annuum cv. Yolo wonder) and safflower (Carthamustinctonus L. cv. Gila) were grown hydroponically and subjectedto a salt stress (51 mol m^–3 NaCl plus 25.5 mol m^–3CaCl₂). Mature photosynthetic source leaves and shoot meristematicsinks (young pepper leaves and safflower buds) were analyzedfor nucleotides by high performance liquid chromatography andfor hexose and acid-soluble P—pepper was still vegetativewhereas safflower had switched to flower bud formation—thesalt stress reduced the fresh shoot yield of pepper by nearlytwo-thirds and of safflower by half. It reduced the ATP pooland ATP/ADP ratio in the source leaves of both species and alsoin the young pepper leaves. It had little or no effect on ATPor other nucleotide pools in safflower buds. The UDPG pool wasnot affected in source leaves or safflower buds, but in theyoung pepper leaves it was reduced by half, along with UTP.These reductions were accompanied by over a 3-fold increasein hexose and a large decrease in ester phosphate. In safflower,on the other hand, salt stress had little or no effect on UDPG,hexose, or ester phosphate in either source leaves or buds.The results suggest that salt stress reduced the growth of pepperbecause it reduced assimilation of photosynthate, possibly aconsequence of reduced UDPG, UTP, and ATP pools in the growingleaves. Salt stress did not so markedly affect assimilationof photosynthate in the more tolerant safflower. Key words: Growth suppression, energy charge, UDPG     

Osmotic Adjustment and Stomatal Response to Water Deficits in Maize

A pot experiment was carried out using five maize {Zea maysL.) cultivars under three soil moisture levels (MPa 0 to –0.05,–0.3 to –0.9 and –1.2 to –1.5) to investigatethe effects of water deficits on osmotic adjustment and stomatalconductance. The degree of leaf rolling and the sugar and nutrientconcentrations in leaf cell sap were measured. Leaf water potential and osmotic potential decreased and stomatalconductance decreased with increasing water deficits. Stomatalconductance correlated positively with leaf water potentialand osmotic potential. Degree of leaf rolling was lower in cultivarswhich maintained higher turgor. Osmotic adjustment of 0.08 to0.43 MPa was found under the lowest soil moisture level in fivecultivars used. Sugar and K were the major osmotic substancesin the maize plant. Sugar, K and Mg concentrations increasedunder water deficit, and correlated negatively with a decreasein osmotic potential. Key words: Zea mays L., leaf water relations, leaf rolling, osmotic adjustment, stomatal conductance, water deficit     

Leaf Water Relations, Osmotic Adjustment, Cell Membrane Stability, Epicuticular Wax Load and Growth as Affected by Increasing Water Deficits in Sorghum

A field experiment was conducted with a non-irrigated waterstress treatment and an irrigated control using four sorghum(Sorghum bicolor L. Moench) cultivars. We investigated the effectsof water deficits on leaf water relations, osmotic adjustment,stomatal conductance, cuticular conductance, cell membrane stability(CMS) measured by the polyethylene glycol (PEG) test, epicuticularwax load (EWL), cytoplasmic lipid content, solute concentrationin cell sap, and growth. Osmotic adjustment was observed under water deficit conditions.Lower osmotic potential enabled plants to maintain turgor anddecreased the sensitivity of turgor-dependent processes. Sugarand K were identified as the major solutes contributing to osmoticpotential in sorghum. Sugar and K concentrations in cell sapincreased by 37·4% and 27%, respectively, under waterdeficit conditions in favour of decreasing osmotic potential.Stomatal conductance and cuticular conductance were lower inthe non-irrigated plants. A wide range in CMS among four cultivarswas observed. CMS increased with increasing water deficits.EWL increased on leaves of water deficient plants and was positivelycorrelated with cuticular conductance and CMS. Membrane phospholipidcontent increased in water-stressed plants. CMS as measured by the PEG test, was influenced by EWL, cuticularthickness, and osmotic concentration of leaf tissues. The cultivarswhich maintained higher CMS, higher EWL, lower cuticular conductance,higher turgor and higher osmotic adjustment under water deficitconditions were identified as drought tolerant. Key words: Sorghum bicolor, cell membrane stability, leaf water relationsosmotic adjustment, water stress     

INDUCTION OF CHROMOSOME MOTION IN THE GLYCEROL-ISOLATED MITOTIC APPARATUS: NUCLEOTIDE SPECIFICITY AND EFFECTS OF ANTIDYNEIN AND MYOSIN SERA ON THE MOTION*

Chromosome motion in glycerol-isolated mitotic apparatus (MA) of sea urchin and starfish eggs was investigated with respect to nucleotide specificity and the effects of antisera against tryptic fragment (Fragment A) of flagellar dynein and starfish egg myosin. The motion was highly specific for ATP. GTP, ITP, CTP, UTP, and ADP caused no displacement of the chromosomes towards the poles. The anti-Fragment A serum completely inhibited chromosome motion in the MA of the sea urchin egg, while antiserum against starfish egg myosin as well as its γ-globulin fraction did not inhibit the motion in the isolated MA of the starfish egg, suggesting that chromosome motion depends upon dynein-microtubule but not upon myosin-actin interaction. In addition, colchicine completely suppressed the chromosome motion in vitro.