Progesterone and Salicylic Acid Elevate Tolerance of Poa pratensis to Salinity Stress

Russian Journal of Plant Physiology - Kentucky bluegrass (Poa pratensis L.) was exposed to salinity in the factorial study with 2 factors including salinity [irrigation with tap water and saline...     

Effects of Sulphur Dioxide on Sugar and Free Amino Acid Content of Pine Seedlings

Treatment of jack pine (Pinus banksiana Lamb.) seedlings with gaseous SO₂ resulted in a shift between the reducing and non-reducing sugars. Increasing concentrations of gaseous SO₂ caused an increase in reducing sugars and a decline in the non-reducing sugars, suggesting a conversion from the latter to the former at high SO₂ concentrations. The total amino acid content of the intact tissues also increased with increasing concentrations of gaseous SO₂. Gas-liquid chromatographic analyses of the amino acids indicated that SO₂ (1. 34 mg · m^-3 for 96 h) resulted in an increase in the content of alanine, valine, glycine, isoleucine, leucine, threonine, aspartic acid tyrosine, lysine, and arginine, and a decrease in the content of serine and glutamic acid. The enzymatic and other implications of such changes are discussed.     

Amino Acid and Sugar Transport in Rabbit Ileum

L-Alanine and 3-O-methyl-D-glucose accumulation by mucosal strips from rabbit ileum has been investigated with particular emphasis on the interaction between Na and these transport processes. L-Alanine is rapidly accumulated by mucosal tissue and intracellular concentrations of approximately 50 mM are reached within 30 min when extracellular L-alanine concentration is 5 mM. Evidence is presented that intracellular alanine exists in an unbound, osmotically active form and that accumulation is an active transport process. In the absence of extracellular Na, the final ratio of intracellular to extracellular L-alanine does not differ significantly from unity and the rate of net uptake is markedly inhibited. Amino acid accumulation is also inhibited by 5 x 10^-5 M ouabain. 3-O-methyl-D-glucose accumulation by this preparation is similarly affected by ouabain and by incubation in a Na-free medium. The effects of amino acid accumulation, of ouabain, and of incubation in a Na-free medium on cell water content and intracellular Na and K concentrations have also been investigated. These results are discussed with reference to the two hypotheses which have been suggested to explain the interaction between Na and intestinal nonelectrolyte transport.     

我国梨果糖酸含量的研究

探讨了国内１３９种鲜梨可溶性糖、可溶性固形物、可滴定酸的含量情况,给出了各种梨的糖酸比,为进一步提高梨的品质、制定绿色食品鲜梨标准提供依据     

Small Intestinal Sugar and Amino Acid Transport in Semistarvation

The effect of semistarvation on small intestinal transport of D-glucose, L-valine, and NaCl was studied in an in vitro system of isolated rat brush border membrane vesicles. Whereas semistarvation enhanced the transport rate for L-valine by 19-29%, there was no change in D-glucose transport. When energy in the form of a NaSCN gradient was supplied to the membrane vesicles prepared from semistarved animals, L-valine was concentrated to a greater extent than those from well-fed animals. Strain differences were observed in the manner semistarvation affected NaCl transport across the brush border membrane. Semistarvation increased the NaCl transport rate by a factor of 3.5 in one rat strain and not at all in another. These results provide a partial explanation for the cellular basis of elevated neutral amino acid absorption by the small intestine in semistarvation.     

Photomorphogenically Defined Light and Resistance of Poa pratensis to Drechslera sorokiniana

Photomorphogenic light definitions were derived by mathematical determination of the estimated phytochrome photoequilibrium for each light treatment spectrum. A wide range of photomorphogenic light treatments represented by spectra with estimated phytochrome photoequilibria of 0.45, 0.54, 0.60, 0.67, and 0.71 was utilized to determine the influence of photomorphogenically defined light on resistance of Poa pratensis L. to pathogenesis by Drechslera sorokiniana. Accurate resolution of D. sorokiniana leaf spot development required evaluation of separate leaf ages due to the sequential appearance, development, and senescence of P. pratensis leaves. Disease development (all light treatments) was greatest on leaf 4 (oldest, postmature) followed by leaf 1 (youngest, premature). Low levels of disease occurred on leaves 2 and 3 (mature). Photomorphogenic light defined by estimated phytochrome photoequilibria greater than 0.60 (natural light 0.60) was most disease promotive on leaf 1. Conversely, photomorphogenic light defined by estimated phytochrome photoequilibria of less than 0.60 was most disease promotive on leaf 4. These responses indicate that inherent resistance or susceptibility expressed by P. pratensis to pathogenesis by D. sorokiniana is regulated in part by leaf age (developmental senescent stage) and by photomorphogenically defined light quality. A hypothesis is presented and discussed which integrates and speculates on these observations with respect to the literature.     

Inhibition of Sugar and Salt Elimination by Glands with the Amino Acid Analog p-Fluorophenylalanine

The amino acid analog p-fluorophenylalanine (FPA) inhibitedsugar and K⁺ secretion by nectary glands. FPA specifically reducedthe net excretion of Na⁺ and Cl^– by the salt glands ofthe halophyte Limonium vulgare and ³⁶Cl^–excretion by theglands of the pitcher walls of the carnivorous plant Nepenthes.Net uptake and net accumulation of Na⁺ and Cl^– by Limoniumleaf tissue and ³⁶Cl^– accumulation in Nepenthes pitchertissue were much less inhibited than excretion. The resultsare discussed in relation to literature reporting similar specificeffects of FPA on transport of ions from the symplast of barleyroots into the dead xylem elements. Limonium vulgare, Nepenthes hookeriana, salt-glands, excretion, p-fluorophenylalanine     

Gibberellins and the photoperiodic control of leaf growth in Poa pratensis

The role of gibberellins (GAs) in photoperiodic control of leaf elongation in Poa pratensis was studied by both application of exogenous GAs and analysis of endogenous GAs. Leaf elongation was strongly increased under long day (LD, 24 h) conditions at both 9 and 21°C, leaf length at 9°C LD being similar to that in plants grown in short days (SD, 8 h) at 21°C. However, even at 21°C leaf elongation was enhanced by LD. Exogenous GA₁ could completely compensate for LD at both 9 and 21°C. Gibberellins A₂₀, A₁₉ and A₄₄ could also partly replace LD, but they were significantly less active than GA₁, GA₅₃ was inactive when applied to plants grown at 9°C in SD and exhibited only marginal activity at 9°C LD and 21°C SD. The total level of GAs of the early 13-hydroxylation pathway (A₅₃, A₄₄, A₁₉, A₂₀ and A₁) increased rapidly when plants were transferred from SD to LD at 9°C. After transfer from 9 to 21°C, there was an increase in GA levels at both LD and SD, followed by a decrease under LD conditions. In all cases, GA₁₉ was the predominant GA, accounting for 60 to 80% of the analysed GAs. Levels of the bioactive GA₁ were low and increased transiently by LD four days after transfer from SD to LD. At both temperatures, the ratio GA₁₉ to GA₂₀ and GA₂₀ to GA₁ at 9°C was enhanced by LD compared with SD. Taken together, these results support the hypothesis that photoperiodic regulation of leaf elongation in Poa pratensis is GA-mediated, and they indicate a photoperiodic control of oxidation of GA₅₃ to GA₄₄ and GA₁₉ to GA₂₀, and perhaps also of 3β-hydroxylation of GA₂₀ to GA₁.     

A new Epichloe species with interspecific hybrid origins from Poa pratensis ssp. pratensis in Liyang, China

We describe a new Epichlo? species found in symbiosis with Poa pratensis ssp. pratensis in Liyang, China. Stromata characteristic of Epichlo? spp. were present on some of the reproductive tillers of individual host grasses. Only three of the 98 stromata observed on field plants became orange and produced perithecia. Phylogenetic analyses based on sequences of tubB and tefA indicated that this Epichlo? sp. was an interspecific hybrid related to both E. yangzii and members in the E. typhina complex clade (ETC). Allele-1 of tefA and tubB grouped in the E. bromicola/E. yangzii clade; allele-2 of these two genes clustered in a distinct subclade in the ETC. This is the first report of an Epichlo? species that has interspecific hybrid origins. We propose the name Epichlo? liyangensis Z. Wang, Y. Kang et H. Miao, sp. nov. for this species.     

The Sugar Model: Catalysis by Amines and Amino Acid Products

Ammonia and amines (including amino acids) were shown tocatalyze the formation of sugars from formaldehyde andglycolaldehyde, and the subsequent conversion of sugars tocarbonyl-containing products under the conditions studied (pH5.5 and 50°C). Sterically unhindered primary amineswere better catalysts than ammonia, secondary amines, andsterically hindered primary amines (i.e.-aminoisobutyric acid). Reactions catalyzed by primaryamines initially consumed formaldehyde and glycolaldehyde about15–20 times faster than an uncatalyzed control reaction. Theamine-catalyzed reactions yielded aldotriose (glyceraldehyde),ketotriose (dihydroxyacetone), aldotetroses (erythrose andthreose), ketotetrose (erythrulose), pyruvaldehyde, acetaldehyde,glyoxal, pyruvate, glyoxylate, and several unindentifiedcarbonyl products. The concentrations of the carbonyl products,except pyruvate and ketotetrose, initially increased and thendeclined during the reaction, indicating their ultimateconversion to other products (like larger sugars or pyruvate).The uncatalyzed control reaction yielded no pyruvate orglyoxylate, and only trace amounts of pyruvaldehyde, acetaldehyde and glyoxal. In the presence of 15 mM catalyticprimary amine, such as alanine, the rates of triose andpyruvaldehyde of synthesis were about 15-times and 1200-timesfaster, respectively, than the uncatalyzed reaction. Sinceprevious studies established that alanine is synthesized fromglycolaldehyde and formaldehyde via pyruvaldehyde as its directprecursor, the demonstration that the alanine catalyzes theconversion of glycolaldehyde and formaldehyde to pyruvaldehydeindicates that this synthetic pathway is capable ofautocatalysis. The relevance of this synthetic process, namedthe Sugar Model, to the origin of life is discussed.     

草地早熟禾种子产量构成因素的品种差异

对草地早熟禾 2 8个品种种子产量及性状进行了研究 .结果表明 ,2 8个品种间种子产量存在极显著差异 (P <0 .0 1) ,最高的品种为Balin和Monoply ,其产量达 6 4 3.4～ 6 5 0 .2kg·hm-2 ,为最低品种Elysee(90 .1kg·hm-2 )的 7.1倍 .生产性状相关分析表明 ,生殖枝数 /株、生殖枝高、花序长及小穗数 /生殖枝 4个性状为影响早熟禾种子产量的主要因素 .依据对种子产量及上述 4个性状测定值的聚类分析 ,可将 2 8个品种的种子生产性能分为极强、很强、强、中等、差和极差 6个类群 ,其中Monoply等 6品种为极强类群 ;Baronie、Balin和Sydsport、Entopper分别为很强和强类群 ;Nublue等 12品种为中等类群 ;Broadway等 4品种和Ram1、Elysee分别为差和极差类群     

Sugar, Amino Acid and Inorganic Contents in Rice Phloem Sap

Rice phloem sap was obtained through severed stylets of brownplanthoppers and its chemical composition was determined. Sucrose,the only sugar detected, was present at 17–25% (w/v) inthe sap. Amino acids were present at a total of 3–8% (w/v)and were found to be mostly in a free form. The amount of boundamino acids was estimated to be small, if any were present.Among the free amino acids, asparagine (17–33% on a molarbasis), glutamate (6–14%), serine (10–13%), glutamine(7–15%), threonine (5–6%) and valine (6–7%)were dominant, while cystine and methionine (0–0.2%) werepresent in minor amounts and -aminobutyric acid was not detected.The sap had a slightly alkaline pH (ca. 8.0). The inorganicconstituents detected by electron probe x-ray microanalyzerwere Na, S, P and K, with the K content being the highest. Theosmotic pressure was estimated to be 13–15 atm. The aminoacid composition of the plant parts was determined and the differencesin the ease of phloem loading among amino acids were compared. (Received October 5, 1981; Accepted December 17, 1981)     

枣树叶中氨基酸的含量

通过对枣树叶中氨基酸进行测定证实,两个品种之间在氨基酸总量上无显著性差异,氨基酸含量最高的是谷氨酸、最低的是蛋氨酸。     

Interaction of photoperiod and gibberellin on growth and photosynthesis of high-latitude Poa pratensis

The relative growth rate of pot-grown plants of Poa pratensis L. cv. Holt, origin 69s°N, was increased by 20–40% by photoperiod extension with low intensity incandescent light from 8 to 24 h at 9–21°C. The main increase occurred over the 14 to 18 h photoperiod range. The true photoperiodic nature of the response was demonstrated by the effectiveness of night interruption in stimulating growth. Fortnightly sprayings with gibberellic acid (GA₃) (3 × 10^-6 to 3 × 10^-5 M ) mimicked all the effects of long days, whereas (2-chloroethyl)-trimethylammonium chloride (CCC) counteracted the effects of long days. Both growth substances exhibited pronounced interactions with photoperiod, GA₃ being most effective in short days and CCC in long days. The growth stimulation, whether caused by long days or GA₃, was exerted mainly through increases in individual and total leaf area. This was associated with a reduction in CO₂, exchange rate and a parallel fall in specific leaf weight. Proportionally, however, the increase in leaf area was greater than the fall in CO₂ exchange rate, resulting in a 38 to 118% increase in photosynthesis per leaf. No evidence was found of any direct and promotive effect of transition to long days on the CO₂ exchange rate of already expanded leaves.     

Amino Acid Control over Deoxyribonucleic Acid Synthesis in Escherichia coli Infected With T-Even Bacteriophage

Starvation for a required amino acid of normal or RC(str)Escherichia coli infected with T-even phages arrests further synthesis of phage deoxyribonucleic acid (DNA). This amino acid control over phage DNA synthesis does not occur in RC(rel)E. coli mutants. Heat inactivation of a temperature-sensitive aminoacyl-transfer ribonucleic acid (RNA) synthetase similarly causes an arrest of phage DNA synthesis in infected cells of RC(str) phenotype but not in cells of RC(rel) phenotype. Inhibition of phage DNA synthesis in amino acid-starved RC(str) host cells can be reversed by addition of chloramphenicol to the culture. Thus, the general features of amino acid control over T-even phage DNA synthesis are entirely analogous to those known for amino acid control over net RNA synthesis of uninfected bacteria. This analogy shows that the bacterial rel locus controls a wider range of macromolecular syntheses than had been previously thought.     

番木瓜感染环斑花叶病毒后蛋白质和还原糖的变化

本文对番木瓜不同抗性的品种感染环斑花叶病毒后,可溶性蛋白含量和电泳谱带以及还原糖含量的变化规律进行了研究,并分析其与抗性的关系。结果表明,接种处理后,感病品种(岭南种)的可溶性蛋白含量变化率的峰值较抗病品种(穗中红48号)出现早且高;前者出现在接种后24h,高达54.6%,而后者出现在接种后48h,为38.2%。在未接种处理时,感病品种叶片可溶性蛋白谱带较抗病品种多1条;但在接种初期(接种后24h),抗病品种的蛋白谱带比感病品种多1条(Rf值为0.602)。不同抗性品种在接种后的还原糖含量变化也有差异,抗病品种的还原糖含量变化率在接种后48h达到高峰,峰值为12.3%;而感病品种的还原糖含量变化率在接种后都为负值。