盐胁迫下盐芥渗透调节物质的积累及其渗透调节作用

用含有NaCl0、50、100、200、300、400mmol/L的Hoagland培养液处理盐芥幼苗一定时间后,分别测定其根和叶含水量、渗透势、几种无机和有机渗透调节物质含量,并计算了渗透调节物质在不同条件下的计算渗透势值(COP).结果表明:随盐处理浓度的增加,盐芥根和叶的含水量和渗透势逐渐降低;Na 和Cl-是根和叶积累的无机渗透调节物质;SS、OA和FAA是根积累的有机渗透调节物质,Pro是叶和根积累的有机渗透调节物质.Na X-ray微区分析表明液泡是积累Na 的主要部位.     

Photosynthesis and Photorespiration in Lolium multiflorum and Lolium perenne

The response of net photosynthesis to changing light-flux densityby leaves of Lolium multiflorum (S. 22) and L. perenne (S. 321)is more adequately described by current models when a term allowingfor photorespiration is included. The magnitude of this termwas determined from the changes in the slope of the light-responsecurves for net photosynthesis. A pseudo first-order rate-constantfor photorespiration, and a pseudo second-order rate-constantfor photosynthesis calculated by this technique for L. multiflorumwere found to be similar to corresponding parameters calculatedfrom light-compensation-point measurements using a simple modeldescribed by Brown (1969). The relative magnitudes of respirationand photosynthesis at light saturation for both Lolium specieswere similar to reported values for other temperate species(Lake, 1967). Two selection lines of L. perenne (S. 321) with contrastingdry-matter yields were found to have the same parameters forrespiration and photosynthesis.     

渗透胁迫对皱果苋叶片渗透调节物质的影响

目的:研究渗透胁迫下皱果苋的渗透调节物质变化,探讨皱果苋的耐旱机理.方法:分别用浓度为5%、10%和20%PEG6000进行渗透胁迫,处 理皱果苋幼苗0、1、3、5和7d,取叶片测定各项生理指标.结果:随着渗 透胁迫时间的延长,皱果苋幼苗叶片中相对含水量(RWC)逐步下降;而脯氨酸和可溶性糖含 量上升;在5d,5%、10%、20%PEG胁迫下的叶片脯氨酸含量分别是对照的3.73、6.27、9.77 倍;而叶中可溶性糖含量分别是对照的2.87、3.68、5.21倍.胁迫3d,20%PEG处理的材料出 现萎焉现象,胁迫5d,10%PEG处理的材料开始萎焉;在5%和10%PEG胁迫下,可溶性蛋白含量 升高,但在20%PEG胁迫下,可溶性蛋白含量先升后降.结论:在适度的渗 透胁迫下,皱果苋叶片中的渗透调节物质使其具有较强的渗透能力,形成皱果苋耐旱性的内在基础.     

Nitrate Accumulation and Osmotic Regulation in Italian Ryegrass (Lolium multiflorum Lam.)

The role of nitrate accumulation was studied in osmotic adaptationof Italian ryegrass (Lolium multiflorum Lam. cv. Romo). Plantswere grown under different light intensities (68 and 143 W m^–2)and on Hoagland nutrient solution with a solute potential of0.035 MPa and –0.335 MPa. The solute potential of thenutrient solution was decreased by addition of NaCl, which wastaken up by the plant, and PEG 6000 which was not. At each growingcondition the solute potential of the expressed plant sap wasconstant during the experimental period of 19 d, but was decreasedby increase in light intensity and addition of osmotic substancesin the root medium. At sugar concentrations between 20 and 60mg per gram plant water a change in sugar concentration is osmoticallyfully compensated for by an opposite change in nitrate concentration.At sugar concentrations lower than 20 mg per gram plant waterthere is an overcompensation of nitrate. The overcompensationincrease is attributed to a concomitant decrease of other organicsolutes such as amino acids and organic acids. When NaG is addedto the nutrient solution, the nitrate concentration in the plantdecreases and the solute potential is decreased by uptake ofchloride. With PEG the nitrate content of the plant also decreased.The solute potential of the plant sap is decreased by accumulationof sugar, at least at the high light intensity. Key words: Lolium multiflorum, Nitrate accumulation, Light intensity, Osmotic regulation     

Freezing Tolerance and Solute Changes in Contrasting Genotypes of Lolium perenne L. Acclimated to Cold and Drought

Clonal ramets of 12 contrasting genotypes of Lolium perenneL. were grown in sand or soil-based compost and maintained underwell-watered conditions at 20/15°C or acclimated to lowtemperature (2°C) or to a restricted water supply. Freezingtolerance was measured as LT₅₀ following exposure to sub-zerotemperatures in a freezing tank. Measurements were also madeof osmotic potential, water-soluble carbohydrates, free proline,free amino acids, and minerals in entire tillers. Acclimationto both drought and cold lowered LT₅₀, induced osmotic adjustment,and increased concentrations of proline and amino acids, Rootingmedium had little effect on LT₅₀, but caused large differencesin osmotic potential and in proline and amino-acid concentrations.There was considerable genetic diversity for all charactersmeasured, except for mineral contents. There was, however, norelationship between LT₅₀ and osmotic potential or solute contentthat was consistent across the three sources of variation (growingmedium, acclimation, genotype). Furthermore, the diverse genotypicvalues of cold-induced freezing tolerance were not correlatedwith those of drought-induced tolerance. It is concluded thatmore precise measurements are needed of the partitioning ofsolutes during acclimation and of the sensitivity of differentorgans and tissues to freezing.Copyright 1993, 1999 AcademicPress Perennial ryegrass, hardening, acclimation, osmotic potential, solute potential, carbohydrates, proline     

Comparison of Salt-Induced Osmotic Adjustment and Trigonelline Accumulation in Two Soybean Cultivars

21-d-old seedlings of the soybean (Glycine max) cvs. Essex and Forrest were treated with NaCl in a step-wise manner over 9 d (3 d 30 mM, 3 d 70 mM, and 3 d 100 mM) and maintained under 100 mM NaCl for an additional 14 d. During salt treatment, osmotic potential decreased more in cv. Forrest relative to cv. Essex. In non-stressed leaf tissue, cv. Forrest contained more trigonelline (TRG) relative to cv. Essex. During salt treatment, TRG amounts increased in cv. Forrest but were unchanged in cv. Essex. Both cvs. osmotically adjusted in response to salt stress; the maximal osmotic adjustment was 0.80 and 0.18 MPa in cv. Forrest and cv. Essex, respectively. This revised version was published online in June 2006 with corrections to the Cover Date.     

Accumulation of Trehalose as a Compatible Solute under Osmotic Stress in Euglena gracilis Z

ABSTRACT. The photosynthetic protozoon Euglena gracilis, accumulated a large amount of trehalose in the cells under salt or osmotic stresses. Radioactivity of [14C] paramylon, a β-1,3-polyglucan which was stored in the cells of E. gracilis. was degraded rapidly and this radioactivity was almost stoichiometrically incorporated into trehalose. The interconversion of trehalose from paramylon by salt or osmotic stresses was dependent on the concentrations or osmotic pressures, suggesting that E. gracilis accumulate trehalose as an osmoprotectant. After the removal of salt or osmotic stresses, trehalose was gradually degraded, however, it was not converted into paramylon.     

多年生黑麦草的组织培养和植株再生

1植物名称多年生黑麦草(Lolium perenne)栽培品种"德比"(Derbv). 2材料类别成熟种子. 3培养条件(1)愈伤组织诱导培养基:N6 2,4-D10.0 mg·L-1(单位下同) 6-BA 0.5 NAA 0.5 CH(水解酪蛋白)500;(2)继代培养基:N6 2,4-D 5.0 NAA 0.5 6-BA 0.5 CH 300;(3)分化培养基:N6 6-BA 1.0 KT 0.5;(4)壮苗培养基:N6;(5)生根培养基:1/2N6 NAA 0.2.以上培养基中除生根培养基蔗糖含量为3%以外,其余均为5%.pH 5.8,琼脂含量为6.5%.愈伤组织诱导及继代为暗培养;分化培养及生根培养的光照度均为1800 1x,光照时间12 h·d-1,培养温度(25 2)℃.     

黑麦草内生真菌感染状况的检测及定量分析

选取内生真菌特异性引物,成功建立了利用PCR技术对黑麦草中内生真菌感染状况的检测和定量分析方法。此检测方法的准确性高于常规乳酸-苯胺蓝染色法。利用实时荧光PCR定量分析的结果表明：不同植株之间内生真菌含量差异较大,而同株植物相同龄级分蘖之间内生真菌含量无显著差异。由此可见内生真菌的含量不仅与植物种以及品种有关,也与植物的基因型密切相关。     

多年生黑麦草种子萌发及植株再生的研究

对不同预处理条件下多年生黑麦草种子萌发、愈伤组织诱导以及植株再生进行了研究。结果表明,35℃恒温干燥处理3 h、浸泡16 h后,室温晾48 h的干湿交替及强度为1 000 GS磁场处理30 min均能使种子的发芽率得到显著提高。最适诱导培养基为MS+2,4-D 6 mg·L^-1,有机添加物对于愈伤组织的生长影响并不显著,但可以改善其状态;较为适宜的分化培养基为MS+2 mg·L^-1 6-BA或KT;生根培养基为附加0.5 mg·L^-1 NAA的MS培养基。     

Mineral nutrition and the reaction of Lolium perenne to defoliation

Summary Plants were grown in nutrient solutions, defoliated to remove all expanded leaf blades and the amount of regrowth measured a week later. Prior to defolation, plants in concentrated nutrient solutions grew more rapidly than those in dilute solutions. After defoliation, the plants in concentrated solutions did not produce, however, a greater quantity of regrowth relative to their size than those in dilute solutions. Other things being equal, in environments which produced plants with a low root: shoot ratio, the greatest amount of regrowth was produced by genotypes with a higher than average root: shoot ratio, and vice versa.These results are discussed in relation to repeated defoliation, size and age of the plants, and the role of roots and reserve substances in recovery from defoliation     

The genetics of meiotic chromosome pairing in Lolium temulentum x Lolium perenne tetraploids

Summary The degree of preferential pairing of homologous chromosomes was estimated in a series of tetraploid hybrids of Lolium temulentum x Lolium perenne by means of cytological and genetic analyses. The correlations between the frequency of bivalents at first metaphase of meiosis in the hybrid tetraploids and the degree of preferential pairing calculated from the segregation pattern of isozyme alleles in a test cross was extremely high. The results showed clearly that suppression of heterogenetic pairing in these Lolium tetraploids is achieved by a genetic system involving the A chromosomes as well as the B chromosome system which has been known for some time. Certain similarities with the genetic system controlling pairing in polyploid wheats are discussed.     

Selection and stability of synthetic varieties of Lolium perenne

Summary The performance of three experimental cultivars of Lolium perenne selected for yield or water soluble carbohydrate content was monitored over four generations of seed multiplication under relaxed selection. In each variety the selected trait regressed towards that of the base population from which the selection line derived. This could be accounted for by residual genetic variation within the lines for the selected trait, and in some instances, by association of this variation with the fitness character, seed numbers produced. These results emphasize the need for practical breeding programmes to consider the nature of the gene action controlling the selected trait, if additive, directional selection should be effective in increasing the expression of the character. Where ambidirectional dominance and epistasis are important, consideration should be given to means of achieving reassortment of the controlling genes prior to selection.     

Synaptonemal complex formation in hybrids of Lolium temulentum x Lolium perenne (L.)

Comparisons were made between two kinds of tetraploids derived from the hybrid Lolium temulentum x L. perenne. One hybrid behaves like an autotetraploid with multivalents at first metaphase of meiosis in pollen mother cells. The other behaves like an allotetraploid, in which pairing at first metaphase is restricted to bivalents comprised of strictly homologous chromosomes. The diploidisation of the latter form is controlled by determinants located on both the normal, A chromosomes and on supernumary B chromosomes. Reconstruction of synaptonemal complexes and their elements, from serial sections through pollen mother cell nuclei examined under the electron microscope, reveals that at zygotene pairing in both forms results in multivalent formation involving non-homologous as well as homologous chromosomes. The mechanism responsible for the diploidisation is, therefore, not based on a restriction of pairing at early meiosis to homologous chromosomes but on a correction or transformation of the multivalent chromosome associations to bivalents subsequent to zygotene. The transformation is not completed until late pachytene. In the multivalent-forming tetraploid a maximum of four chromosomes are associated at first metaphase. Yet configurations of a higher valency are found at zygotene. There is, therefore, a partial transformation of multivalents even in this autotetraploid form which restricts configurations at metaphase I to homologous and homoeologous chromosomes only. In both hybrids some homologous bivalents are not the product of resolution of multivalents but result from two-by-two pairing from the beginning of zygotene.     

Effect of Osmotic Stress on Carbon Metabolism in Chlamydomonas reinhardtii: Accumulation of Glycerol as an Osmoregulatory Solute

NaCl, KCl, and sucrose at equiosmolar concentrations had similar inhibitory effects on photosynthetic carbon metabolism by the freshwater green alga, Chlamydomonas reinhardtii. Inhibitory concentrations of these solutes altered the products of photosynthetic ¹⁴CO₂ incorporation, resulting in reduced incorporation into starch, sugar phosphates, lactate, and glycolate, but caused an accumulation of glycerol both intracellularly and in the medium.