不同浓度硝态氮供应下小麦生长、硝态氮累积及根系钙信号特征

以小麦品种‘石麦15’和‘衡观35’为材料进行营养液水培试验,研究不同浓度硝态氮供应对小麦苗期根系形态、钙离子流特征及钙调蛋白(CaM)含量的影响。结果表明,与适宜浓度硝态氮处理(2.5mmol/L)相比,无外源硝态氮供应时小麦地上部鲜重、硝态氮含量均降低,侧根数量显著减少;高浓度硝态氮处理(50mmol/L)下两个小麦品种地上部硝态氮含量升高,根系总长度降低,‘石麦15’侧根数量减少。无硝态氮和高浓度硝态氮处理下,根系中钙调蛋白含量降低,且‘衡观35’的降低幅度大于‘石麦15’。无外源硝态氮供应时小麦根尖表现出较为明显的钙离子外流特征;与适宜浓度硝态氮处理相比,高硝态氮处理下小麦根尖Ca2+的内流速度显著下降。说明硝态氮供应不足和高浓度硝态氮供应会影响小麦根系生长,根系Ca2+外流或Ca2+内流速度下降,CaM含量减少,Ca2+/CaM可能介导硝态氮调控小麦根系生长发育。     

牛磺酸对小麦幼苗生长的生理效应

采用牛磺酸溶液培育小麦幼苗,测定10、100、500、1 000、5 000 mg/L的牛磺酸对小麦幼苗的光合作用PS Ⅱ光化学效率、细胞膜相对透性和膜脂过氧化以及生长的影响.结果表明,与对照组相比,适宜浓度的牛磺酸处理可促进小麦幼苗的生长,使其根长、株高、单株幼苗的干重和鲜重增加,并在一定程度上提高叶片的光化学效率,降低细胞膜相对透性和膜脂过氧化产物的含量;最适处理浓度约为500 mg/L.说明牛磺酸对小麦幼苗细胞膜有一定的保护作用.     

Nitrate Uptake and the Induction of Nitrate Reductase Activity in Wheat (Triticum aestivum L.) Seedlings

Nitrate uptake and the subsequent induction of in vivo nitratereductase activity in wheat were studied by investigating aeuploid and certain ditelosomic stocks which exhibited in vivoactivity significantly greater than that of the euploid. Thekinetics of nitrate uptake were investigated, but the high activitiesof the ditelosomics were not caused by increased uptake of nitrate,although ditelo-7B^L exhibited unusual uptake dynamics. Analysisof the induction of nitrate reductase activity revealed a biphasicgeneral pattern, with an initial rapid phase being followedby a slower but longer period of induction. The induction rateover the second period, although responsible for only a minorproportion of the total activity induced, was positively correlatedwith the final nitrate reductase level, unlike the rate overthe first induction period. Several stocks exhibited high inductionrates over one or other of the two phases, while ditelo- 1 A^sshowed an abnormal monophasic induction pattern. At the endof the second period of induction, nitrate reductase activitybecame more or less steady, except for activity fluctuationsassociated with the time of application of induction stimuli.     

Light and Dark Controls of Nitrate Reduction in Wheat (Triticum aestivum L.) Protoplasts

Protoplasts were isolated from the leaves of nitrate-cultured wheat (Triticum aestivum L. var. Frederick) seedlings. When incubated in the dark, protoplasts accumulated nitrite under anaerobic, but not under aerobic, conditions. The assimilation of [¹⁵N]nitrite by protoplasts was strictly light-dependent, and no loss of nitrite from the assay medium was observed under dark aerobic conditions. Therefore, the absence of nitrite accumulation under dark aerobic conditions was the result of an O₂ inhibition of nitrate reduction and not a stimulation of nitrite reduction. In the presence of antimycin A, protoplasts accumulated nitrite under dark aerobic conditions. The oxygen inhibition of nitrate reduction was apparently due to a competition between nitrate reduction and dark respiration for cytoplasmic-reducing equivalents.     

Response of Spring Wheat (Triticum aestivum L.) Quality Traits and Yield to Sowing Date

The unpredictability and large fluctuation of the climatic conditions in rainfed regions do affect spring wheat yield and grain quality. These variations offer the opportunity for the production of better quality wheat. The effect of variable years, locations and sowing managements on wheat grain yield and quality was studied through field experiments using three genotypes, three locations for two years under rainfed conditions. The two studied years as contrasting years at three locations and sowing dates depicted variability in temperature and water stress during grain filling which resulted considerable change in grain yield and quality. Delayed sowing, years (2009–10) and location (Talagang) with high temperature and water stress resulted increased proline, and grain quality traits i.e. grain protein (GP) and grain ash (GA) than optimum conditions (during 2008–09, at Islamabad and early sowing). However, opposite trend was observed for dry gluten (DG), sodium dodecyl sulphate (SDS), SPAD content and grain yield irrespective of genotypes. The influence of variable climatic conditions was dominant in determining the quality traits and inverse relationship was observed among some quality traits and grain yield. It may be concluded that by selecting suitable locations and different sowing managements for subjecting the crop to desirable environmental conditions (temperature and water) quality traits of wheat crop could be modified.     

Osmotic Stress-Induced Growth Suppression of Dark-Grown Wheat (Triticum aestivum L.) Coleoptiles

Application of 60 mM polyethylene glycol (PEG) to dark-grownwheat (Triticum aestivum L.) roots substantially reduced growthof coleoptiles. However, when PEG was removed, the growth rateof these coleoptiles greatly increased. Cell walls of stressedcoleoptiles remained loosened as compared with those of unstressedones. The osmotic potential of the stressed coleoptiles decreasedto that of the 60 mM PEG solution. On the other hand, the extentof decrease in the osmotic potential of stressed roots was smallerthan that of stressed coleoptiles. The osmotic potential difference() between the cell sap and the incubation medium of stressedroots was substantially higher than that of unstressed ones.The amount of ink moved from roots, where it was applied, tothe apical region of coleoptiles was significantly reduced underosmotic stress conditions. When water was exogenously appliedto abraded coleoptiles, the growth of these stressed coleoptileswas greatly promoted. These results suggest that inhibitionof coleop-tile growth under osmotic stress conditions is notdirectly related to a decrease in cell wall extensibility orto loss of the capacity to maintain osmotic potential gradients,but is caused by the reduction of the water supply from theroots to the coleoptiles. (Received August 26, 1996; Accepted December 18, 1996)     

Effects of Abscisic Acid on Growth of Wheat (Triticum aestivum L)

Daily application of abscisic acid (ABA) to growing wheat plants,although initially inhibiting growth, resulted, after a shortlag, in an increase in the number of leaves and tillers. Thismay have been due to reduced apical dominance. At 84 days thetotal dry weight and area of all leaves produced up to thistime was less for the plants treated with ABA than for the controlplants. However, the area of green, living leaves and the dryweight were not significantly affected by the ABA treatment.Further effects of the daily ABA treatment were the inhibitionof transpiration, especially on the abaxial surface, the reductionof leaf size, the promotion of flowering and the stimulationof trichome formation on the leaf surfaces. ABA did not promoteleaf senescence in whole plants and actually increased leaflongevity. Triticum aestivum L., wheat, leaf senescence, transpiration, growth, flowering, abscisic acid     

Effects of Nutrient Supply on Pre-emergence Growth and Nutrient Absorption in Wheat (Triticum aestivumL.) and Sugarbeet (Beta vulgarisL.)

Nutrient absorption in wheat and sugarbeet was studied duringpre-emergence growth by adding 0, 7, 10.5 or 14 mol m^-3nitrogen(N) to the growth medium. Seedling growth and carbon, N and¹⁵Ncontents of the seedling parts were measured. Differences betweenthe natural abundance of¹⁵N in seeds and in nutrient solutionwere used to determine the proportion of N in the organs originatingfrom seed reserves and from absorption. Absorption began laterfor wheat than for sugarbeet and had less effect on seedlinggrowth. The absorbed N was found mainly in roots. Compared towheat, sugarbeet seedling N content was greatly altered andthe hypocotyl showed increased elongation when nutrients wereadded. Most of the absorbed N was found in the radicle and hypocotylwith less in the cotyledons. Sugarbeet seedling emergence andearly growth could be decreased by adverse conditions occurringafter sowing by affecting mineral availability in the soil orthrough altered root absorption.Copyright 1998 Annals of BotanyCompany Triticum aestivumL., wheat,Beta vulgarisL., emergence, natural isotopic composition, seedling, seed reserves     

Purification and Characterization of Lipase from Wheat (Triticum aestivum L.) Germ

A method of isolation and purification of lipase (EC 3.1.1.3) from the germ of wheat (Triticum aestivumL.) is described. An electrophoretically homogeneous preparation of the enzyme (specific activity, 622.5 × 10^–3 mol/min per mg protein) was obtained after 61-fold purification. The molecular weight of the enzyme, determined by gel chromatography, was 143 ± 2 kDa. The optimal conditions for the enzyme were 37°C and pH 8.0. The homogeneous preparation of the lipase exhibited high thermal stability: over 20% of the original activity was retained after incubation of the preparation at high temperatures (60–90°C) for 1 h at pH 8.0.     

Biochemical Basis of Variability in Nitrate Reductase Activity in Wheat (Triticum aestivum L.) Genotypes

Significant differences in the activity of nitrate reductasein vivo and in vitro were observed among wheat genotypes, whenexpressed on a dry weight basis. The genotypes with high nitratereductase (HNR) activity exhibited an efficient nitrate inductionsystem. Availability of NADH seemed to be partially responsiblefor the low activities of the enzyme in genotypes categorizedas low nitrate reductase group (‘LNR). Biochemical analysisof the genotypes revealed that ‘HNR’ genotype hadmore active enzyme protein, high rates of enzyme protein synthesisand higher level of steady state nitrate reductase-mRNA relativeto those observed in ‘LNR’ genotype. ¹ Present address: Department of Botany, Faculty of Science,Hamdard University, Hamdard Nagar, New Delhi 110062, India. ² Present address: Institut für Botanik, UniversitätHannover, 3000 Hannover 21, F.R.G.     

Effects of Kinetin on Tiller Bud Elongation in Wheat (Triticum aestivum L.)

Experiments are described in which at four stages of developmentmain tillers of wheat (Triticum aestivum L.) were isolated andinserted in test-tubes containing distilled water or kinetin.Leaves and leaf sheaths were split off to expose a lateral budapproximately 3 mm long whose growth was measured during a periodof 8 days. Kinetin at 6 ppm promoted bud elongation and dry-weightgain at all stages of development and in different light intensitiesand photoperiods. Reducing assimilate supply either by partialdefoliation of the main tiller or treatment with DCMU inhibitedbud growth during the early part of development, an effect whichwas relieved by kinetin. TIBA applied to prevent auxin transportincreased bud growth at the first two but not later stages ofdevelopment. Kinetin also inhibited nodal root growth consistently. At least two phases of bud control in grasses have to be considered,the first being the imposition of apical dominance after initiationof floral organs and stem elongation, the second being the releaseof buds from inhibition around ear emergence. Imposition ofbud inhibition appears to be a function of auxin and assimilatesupply, and at this stage the promoting effects of kinetin maybe through its action of mobilizing flow of assimilates. Therelease of buds at a later stage is apparently not associatedwith auxin, and kinetin may no longer be concerned with assimilateflow but rather with overcoming an inhibitory effect on budgrowth emanating from the leaves.     

Free Polyamines in Senescing Wheat(Triticum aestivum L.)

The free polyamine content of flag leaves, peduncles, rachis,glumes, and grains of wheat (Triticum aestivum L., cv. Castell)plants, ripening under field conditions, has been investigatedduring three consecutive growing seasons. Putrescine was quantitativelythe most important of all polyamines detected in these organs.Concentrations were highest in the grains, glumes and flag leaves.No correlation was found between polyamine content and the onsetof senescence of flag leaves and other organs. Excised primaryleaves, however, showed a decrease in polyamine content in thedark and also in light/dark cycles, but in the latter case onlyafter an initial increase. Sink removal of otherwise intactwheat plants caused an accumulation of putrescine in flag leavesat the later stages of senescence, whereas removal of all otherleaves was without any significant effect. Putrescine was alsorecovered in phloem-exudate samples collected throughout theperiod of grain development. In both grains and glumes, peakconcentrations of polyamines were found early during seed development. Key words: Triticum aestivum, polyamines, ripening, senescence     

Effect of Seed Damage on Growth and Development in Pea (Pisum sativum L.) and Wheat (Triticum aestivum L.)

The effect of damage to the food storage of the seed on theensuing plant was compared in cultivars of two species differingin seed structure, the Greenfeast pea with cotyledons and theGabo wheat with endosperm. Partial removal of storage tissue slightly retarded growth ratein both species and slowed development rate in wheat. Completeremoval lowered the germination rate, drastically slowed thegrowth rate of the survivors for the first 20 d after sowingand lowered the development rate throughout the life cycle. This treatment doubled the time to flower initiation (20 d later)compared with the control, thus indicating the promotive roleof both cotyledon and endosperm in the progress of the shoottowards the reproductive state. The number of vegetative nodes in the pea was lowered by twonodes whereas it was raised by one in the wheat.     

不同小麦品种愈伤组织诱导和再生体系建立

为了筛选适合组织培养的小麦基因型,建立一套有效的小麦诱导再生体系,以24个小麦品种的幼胚为研究材料,选用4种诱导培养基和3种分化培养基,研究了影响小麦组织培养的各种因素。结果表明：①培养基之间存在显著差异,MM2培养基的诱导效果最好,平均诱导率为98．5％,M5B培养基的分化效果最佳,平均分化率为39．8％。②不同品种在诱导愈伤和分化再生上都有显著的基因型差异。③愈伤组织诱导率和分化率之间无显著相关性。     

不同处理条件下小麦胚芽鞘长的遗传分析

以小麦双单倍体(DH)群体(旱选10号×鲁麦14)的150个株系及其亲本为材料,对不同处理条件下的胚芽鞘长、幼苗株高和幼苗生物学产量进行遗传分析,以探讨胚芽鞘长、幼苗株高及幼苗生物学产量的遗传基础及其相关性.结果表明:(1)随着播种深度的增加,胚芽鞘长、幼苗株高显著增加,16.1%PEG-6000处理条件下的幼苗株高显著低于对照,干旱胁迫条件下的幼苗生物学产量显著低于正常供水对照;(2)胚芽鞘长、幼苗株高、幼苗生物学产量的遗传力分别为92.5%、90.3%和78.1%;(3)胚芽鞘长、幼苗株高及幼苗生物学产量均受多基因控制,决定各性状的基因估计数目分别为7、8和14对;(4)根据对性状偏度和峰度系数的估算结果,控制这3个性状的多基因之间均有互补作用;胚芽鞘长与幼苗株高、生物学产量及成熟期株高之间呈显著正相关.     

Effects on Growth and Development of Individual Chromosomes from Slow-growing Lophopyrum elongatum Love when Incorporated into Bread Wheat (Triticum aestivum L.)

Aspects of growth and development were evaluated in the fast-developingannual Triticum aestivum L. ‘Chinese Spring’, theslow-developing perennial Lophopyrum elongatum Löve, theiramphiploid, and chromosome addition and substitution lines ofL. elongatum into ‘Chinese Spring’. Relative growthrates (RGR) of shoots of L. elongatum and the amphiploid werelower than those of ‘Chinese Spring’ (34 and 13%respectively) and main stem development was also slower. Therewas no difference in shoot RGR of any of the chromosome additionor substitution lines and that of ‘Chinese Spring’when assessed between Haun stages 2.0 and 5.0. In contrast,several aspects of plant development were observed to differin the chromosome addition and substitution lines. SubstitutingE genome chromosomes (with the exceptions of 3E and 4E) forD genome chromosomes, or adding E genome chromosomes, slowedthe rate of main stem development, at least up to Haun stage5.0. Despite these differences in the rate of main stem development,the appearance of adventitious roots commenced at approximatelyHaun stage 2.0 in all genotypes. However, the numbers of adventitiousroots and tillers at the 5.0 Haun stage differed between someof the lines when compared to ‘Chinese Spring’.Although incorporation of some L. elongatum chromosomes alteredaspects of plant development, all lines showed more similarityto bread wheat than to L. elongatum, reflecting, in part, thegreater genetic contribution made by bread wheat to these lines.Copyright 2001 Annals of Botany Company Adventitious roots, chromosome addition and substitution lines, Haun stage, Lophopyrum elongatum, relative growth rate (RGR), Triticum aestivum(wheat)     

Floret Initiation and Development in Spring Wheat (Triticum aestivum L.)

The number and developmental stages of florets were determinedin each spikelet of the spike in the main shoots of spring wheat.Samples were taken frequently from plants grown in a phytotronand in a nitrogen application field-test. Ten stages of development,from floret initiation until anthesis, were recognized and described. Inter-spikelet variation in the total number of initiated floretswas rather small. However, the number of florets at advancedstages of development, as well as the number of grains, washighest in the central spikelets in which florets initiatedfirst. Floret initiation did not proceed beyond spike emergence,whereafter the distal florets and the spikelet apex degenerated.Grain-set was restricted to florets which had developed at leastto the stage of visible anther lobes at spike emergence. Thenumber of these florets was increased significantly by nitrogenapplication. Wheat, Triticum aestivum L., spikelet, floret, grain set, nitrogen     

Comparison of in Vivo and in Vitro Assays of Nitrate Reductase in Wheat (Triticum aestivum L.) Seedlings

The effectiveness of the in vivo and in vitro assays for nitrate reductase (NR) in estimating the amounts of reduced N made available to plants was tested against the daily increases in reduced N (Nesslerization) actually accumulated by the plant. With growth-chamber-grown wheat seedlings, the average ratio values (input of reduced N as estimated by the in vitro assay to actual accumulation of N by the plant) were 3.9 for shoots, 3.7 for the roots, and 4.1 for the entire plant, over a 10-day period. With the in vivo assay, the average ratio values were 0.7 for the shoot, 1.8 for the root, and 0.9 for the entire plant. Although the linear regressions between the accumulated N in the plant and the estimated N input (by both in vitro and in vivo assays) were significant and positive, the in vivo assay provided the closest approximation of the actual amount of N accumulated.     

Effect of Water Deficit on Sporogenesis in Wheat (Triticum aestivum L.)

Plants of Triticum aestivum L., cv. Gabo, were grown in a glasshousefor 4 weeks and then transferred to a controlled environmentwith 20±1 °C temperature and 16 h photoperiod. Theywere subjected to water deficit by withholding the water supplyduring various stages of floral development, including thoseimmediately before meiosis and all stages until just after anthesis. The proportion of apparently normal florets which produced grainwas reduced when water deficit occurred during and immediatelyafter meiosis in the generative tissues. The effect of thisreduced grain set on total grain yield was partially compensatedby an increase in the weight of the remaining grains. Cross-pollinationbetween stressed and well-watered plants showed that grain setwas reduced as a direct consequence of the induction of malesterility by water stress, whereas female fertility was unaffected.A large proportion of the anthers on water-stressed plants weresmall and shrivelled, did not dehisce normally and containedpollen which was devoid of normal cytoplasmic constituents andshowed no staining reaction with triphenyl tetrazolium chloride.This effect on male fertility was not a result of desiccationof the sporogenous tissue, but an indirect outcome of the decreasein water potential elsewhere in the plant. Water stress, Triticum aestivum L., wheat, pollen, sporogenesis, grain set, male sterility     

Regeneration of Freezing-Tolerant Spring Wheat (Triticum aestivum L.) Plants from Cryoselected Callus

A cryoselection protocol has been developed that provides freezing-tolerant callus that, in turn, can regenerate plants with enhanced cold hardiness. Tolerant calli were selected from spring wheat (Triticum aestivum L.) callus by immersion in liquid nitrogen without addition of cryoprotectants. Less than 15% of the calli survived the initial challenge, whereas 30 to 40% of previously selected calli survived subsequent exposure. Seed progeny from five of 11 regenerant (R2) lines tested exhibited significantly enhanced tolerance to freezing at −12°C. Thus, cryoselection appears to involve at least in part, selection for genetic rather than epigenetic variants. Analysis of one callus line indicated that cryoselection did not induce significant alterations in lipid composition, adenylate energy charge, or freezing point. An increase in the soluble sugar component was detected. Changes were also detected in the protein complement of microsomal membrane and soluble protein extracts of cryoselected callus. In all, seven unique proteins ranging from 79 to 149 kilodaltons were identified. The results demonstrate that freezing tolerant callus can be isolated from a heterogeneous population by cryoselection, and factors that contribute to hardiness at the callus level are biologically stable and can contribute to tolerance at the whole plant level.