Manipulation Through Liquid Culture in the Contents of Sucrose and Glutamine and Their Transformation to Starch and Protein in Wheat Grain

Detached ears of wheat were cultured in liquid medium manipulated for sucrose and glutamine contents, and the accumulation of starch and protein in relation to the activities of sucrose cleaving—, ammonia assimilating—, and transaminating enzymes was studied in the grain. With an increase in the concentrations of sucrose from 44 to 176 mM and glutamine from 6.4 to 25.7 mM (keeping their ratio at a constant value of 7:1), the contents of starch and protein increased in the grains. However, when the grains were cultured in the medium containing 8.5 to 34 mM glutamine and a fixed concentration of 117 mM sucrose, there was a gradual increase in protein and decrease in starch content in the grain. By such manipulation in the liquid medium, the content of free amino acids also increased in the grain up to 12 days culturing. Amongst sucrose cleaving enzymes, the activities of sucrose-UDP glucosyl transferase and soluble alkaline invertase were much lower than the activity of soluble acid invertase. At high concentration (34 mM) of glutamine in the medium, containing 117 mM sucrose, there was drastic decrease in the activities of soluble acid invertase and UDPG pyrophosphorylase but the activities of ADPG pyrophosphorylase, alkaline inorganic pyrophosphatase, glutamate dehydrogenase, glutamate oxaloacetate transaminase and glutamate pyruvate transaminase increased in the grain with increase in glutamine concentration in the culture medium. Evidently, an increase in the level of amino nitrogen, coupled with an optimum sucrose concentration in the grain raised through liquid culturing enhances the conversion of sucrose to protein at the cost of starch accumulation in wheat.     

麦田3种杂草种子的破眠(简报)

研究麦田常见的3种杂草破眠的结果表明,4-35℃的变温处理、O．3％赤霉素浸泡2h、3．6％盐酸浸泡30min（发芽率达到58．0％）均可打破播娘蒿种子的休眠;9、8％硫酸处理10min、6．6％硝酸处理35min、30％双氧水处理40min、3．6％盐酸处理30min（发芽率达到60．0％）也均可打破野燕麦种子的休眠;麦仁珠种子则以浓盐酸处理5min的破除休眠效果最好,发芽率达到72、0％。     

Factors Affecting Grain Enlargement in Wheat

When most of the grains were removed from wheat ears the remaininggrains developed increased numbers of aleurone and endospermcells, and the increased grain volume was accompanied by anenlarged endosperm cavity. The giant grains usually synthesizedstarch more rapidly than normal grains. Flag leaf photosynthesiswas unaffected and additional sugar was retained in the culmand glumes. Total nitrogen and free amino acid content increased.Gibberellin and auxin concentrations were greater in the glumesof the partly degrained ears, and auxin in the grains was alsogreater than in equivalent grains from intact ears.     

Mitochondrial Efficiency and Grain Yield in Wheat

Mitochondrial ADP/O and RC ratios have been determined in two-day-oldshoots of nine wheat (Triticum aestivum) varieties of knownaverage grain yield. Both ratios were highly correlated withaverage grain yield. ADP/O and RC ratios of germinating shootswere also correlated with yield within a variety when yieldwas varied by irrigation and different nitrogen fertilizer treatments.It is proposed that the observed correlations are the resultof mitochondrial ADP/O and RC ratios being partly controlledduring germination directly or indirectly by seed-based metabolismwhich reflects the metabolic activity and total carbohydratedeposited in seed during seed formation.     

Physiological Factors Limiting Grain Size in Wheat

The effects on grain size of changing the supply of assimilates,by thinning before anthesis or by shading the plants or by halvingthe ears either early or late in grain growth, were studiedin two glasshouse experiments with Kleiber spring wheat (Triticumaestivum L.), in 1976 and 1977. Late treatments had no effect,presumably because little grain growth occurred thereafter.Thinning the plants before anthesis increased, and shading theplants soon after anthesis decreased grain size. Halving theears soon after anthesis increased the size of the remaininggrains, but grain weight per ear decreased. The effect on grainsize of halving the ear tended to be smaller under conditionsmore favourable for photosynthesis, except when the plants werethinned before anthesis. Shading decreased the total amountof nitrogen per culm and the proportion of total nitrogen recoveredin the ear. Halving increased the retention of nitrogen in thestem of unshaded shoots and had no effect on nitrogen distributionwithin shaded shoots. In 1977 halving the ear increased the rate of dry matter accumulationin the grain throughout the grain filling period, but in 1976the increase in dry weight was faster in the grains of halvedears only during early grain growth. Later the grains in halvedand intact ears increased in dry weight at the same rate, eventhough the supply of photosynthate and the capacity of the grains(as measured by volume) were greater in the halved ears. Theseresults are discussed in relation to the influence on finalgrain weight of assimilate supply and the storage capacity ofthe grain.     

Grain Growth Dynamics in Winter Wheat Crops

A procedure for analysing the dynamics of grain growth is developedand applied to data from winter wheat crops. The algorithm estimatesgrowth rate in relation to local data and preserves a shapethrough the whole growth curve by optimization subject to physiologically-justifiedconstraints: that grain growth rate decreases monotonically,and that there is a discontinuity to zero rate at physiologicalmaturity. It is assumed that effects of temperature can be allowedfor by expressing growth in relation to thermal time, accumulatedtemperature above a base temperature. Conditions are derivedunder which an optimal base temperature for grain growth rateexists under these physiological constraints. When applied todata from crops with different sowing dates and nitrogen treatmentsin different years, weak optimal base temperatures of 2.0 and7.5 °C were obtained for growth rate and duration, respectively.Initial growth rates were similar for all crops, but there wereconsiderable variations in rate later in grain growth. Thesevariations were, in part, related to the overall crop growthrate divided by the number of grains. Grain growth, modelling, winter wheat     

Genetic Dissection of Grain Size and Grain Number Trade-Offs in CIMMYT Wheat Germplasm

Grain weight (GW) and number per unit area of land (GN) are the primary components of grain yield in wheat. In segregating populations both yield components often show a negative correlation among themselves. Here we use a recombinant doubled haploid population of 105 individuals developed from the CIMMYT varieties Weebill and Bacanora to understand the relative contribution of these components to grain yield and their interaction with each other. Weebill was chosen for its high GW and Bacanora for high GN. The population was phenotyped in Mexico, Argentina, Chile and the UK. Two loci influencing grain yield were indicated on 1B and 7B after QTL analysis. Weebill contributed the increasing alleles. The 1B effect, which is probably caused by to the 1BL.1RS rye introgression in Bacanora, was a result of increased GN, whereas, the 7B QTL controls GW. We concluded that increased in GW from Weebill 7B allele is not accompanied by a significant reduction in grain number. The extent of the GW and GN trade-off is reduced. This makes this locus an attractive target for marker assisted selection to develop high yielding bold grain varieties like Weebill. AMMI analysis was used to show that the 7B Weebill allele appears to contribute to yield stability.     

小麦籽粒品质性状的QTL分析

利用小麦中国春(母本)和兰考大粒(父本)F2群体构建了169个标记的分子遗传图谱,将F2∶3家系分别种植于3个环境中,利用基于完备区间混合模型的单环境作图模型和多环境作图模型对小麦籽粒容重、硬度、蛋白含量和结合水含量性状进行了QTL分析。结果显示:(1)两种作图模型下,检测到容重的6个共同QTL(QTW-6B-6、QTW-7B-6、QTW-7B-9、QTW-5D-2、QTW-6D-1、QTW-6D-4),单环境模型下遗传贡献率为1.99%~6.57%,多环境模型下遗传贡献率为3.66%~20.07%,其中QM TW-7B-9、QM TW-6D-1和QM TW-6D-4在多环境模型中表现为主效QTL。(2)检测到硬度的3个共同QTL(QHD-4A-5、QHD-7A-1和QHD-7B-9),单环境模型下的遗传贡献率为6.00%~6.95%,多环境模型中遗传贡献率为5.43%~9.64%。(3)检测到蛋白含量1个共同QTL(QPR-6D-1),单环境模型下的遗传贡献率为5.39%,多环境模型中遗传贡献率为10.06%,表现为主效QTL。(4)检测到籽粒结合水含量1个共同QTL(QMO-1B-4),单环境模型下的遗传贡献率为39.20%,多环境模型下的遗传贡献率为75.01%,均表现为主效QTL。(5)1B染色体上存在同时控制籽粒容重、硬度、蛋白和结合水含量的QTL,说明1B染色体对小麦品质的影响可能很大。研究表明,小麦容重、硬度、蛋白含量、结合水含量的遗传主要受加性效应控制。该研究初步定位的一些重要QTL可为进一步精细定位、基因挖掘和育种早代品质性状分子标记辅助选择提供依据。     

The Effects of Floret Sterilization on Grain Number and Grain Weight in Wheat Ears

This paper describes the effects of sterilizing certain floretson the development of others within the ears of wheat, cultivarMaris Ranger. Sterilization of all the florets in spikelets2, 4, 6, and 8 (numbered from the base of the ear upwards) ledto more grain setting and greater grain growth in the untreatedspikelets. These compensatory increases were insufficient toprevent a depression in the yield of grain per ear. Sterilizationof more than one of the basal florets of spikelet 8 led to amore frequent setting of the grain in the distal florets onthat spikelet and to the centrally positioned grain becomingheavier. The physiological basis for the inhibitory influences of theolder and developing grain on the unfertilized florets and youngergrain is discussed.     

Grain Yield in Two Contrasting Varieties of Spring Wheat

To investigate factors determining grain yield in spring wheattwo contrasting varieties of high (Jufy I) and low (Peko) yieldingcapacity were grown in field and glasshouse experiments. In a field trial Jufy I yielded approximately 14 per cent moregrain than Peko on both control and nitrogen-treated plots.In another field trial employing small plots, although for bothvarieties doubling the seed-rate did not affect grain yield,the two varieties differed in their response to the increasein density. In Peko the yield level remained unaffected becausedoubling the seed-rate halved the number of fertile tillersper plant, whereas for Jufy I in addition to a shift in tillernumber per plant there were changes in the number of grainsper ear. In both varieties the weight per seed remained constant. When the two varieties were grown alone or as a 1: 1 mixtureat the same seed-rate the grain yields were similar. In themixture, Peko, compared with Jufy I, produced a greater numberof fertile tillers and consequently a greater contribution tothe total grain yield. In glasshouse experiments the grain yield per tiller and theorder of leaf area duration per tiller for the period from earemergence to grain ripening were both higher for Jufy I. Onthe other hand, there was no varietal difference for the netassimilation rate estimated during the vegetative phase, butexcluding the roots. Additional nitrogen primarily stimulated tiller production inboth varieties. Shading either the upper or lower parts of the plant demonstratedthat the ear and flag leaf and its sheath are important sourcesof assimilates for grain formation, whereas the lower partsare relatively unimportant in this respect. There were indicationsthat the response between varieties differed.     

Mitochondrial Complementation and Grain Yield in Hybrid Wheat

ADP/O ratios, cytochrome c oxidase and adenosine triphosphatasehave been measured in mitochondria and mixtures of mitochondriaisolated from two day-old shoots of wheat of known F₁ hybridgrain yield performance. Mixtures of mitochondria from two varieties,Peko and Cappelle-Desprez, which have considerable F₁ hybridyield heterosis, showed a significantly increased ADP/O ratioover the mean value for mitochondria from the varieties assayedindividually, i.e. these varieties showed ‘mitochondrialcomplementation’. No mitochondrial complementation wasdetected for cytochrome c oxidase or adenosine triphosphatase.In other mitochondrial mixtures no complementation in ADP/Oratios were found even when the varieties showed F₁ hybrid yieldheterosis. Mitochondrial ADP/O ratios were studied in six varietiesindividually and in mixtures. In only one mixture was any significantcomplementation detected. However, when all the results wereconsidered together, mitochondrial complementation was significantlycorrelated with F₁ hybrid grain yield heterosis when the plantswere grown at a low seed density but not at a high seed density.New hypotheses are offered to account for mitochondrial complementationand its statistical relationship with yield heterosis.     

An Improved Pollen Grain Smear Method for Wheat

Anthers containing actively dividing pollen grains were treated 1 hour at 18-20° C. with 0.2% solution of colchicine, washed 1 hour in water, soaked in 0.002 M aqueous solution of 8-oxyquinoline at 10-14° C. for 1 hour, washed in water for 1 hour and then fixed in Carnoy's solution (alcohol, chloroform, acetic acid, 6:3:1) for 6 hours to overnight. They were washed successively in acetic-alcohol (1:1) 10-15 minutes, 70% alcohol 10-15 minutes and in water 30 minutes before hydrolysing them in bulk in 1 N HCl at 60° C. for 10-15 minutes. “Finally, they were stained in leuco-basic fuchsin for 15-30 minutes. Pollen grains were squeezed out of a stained anther in a small drop of egg albumen on a slide and the albumen smeared uniformly on the slide. The slide was dipped successively for a few seconds in glacial acetic acid and 45% acetic acid respectively. The smear was covered by a cover glass in a drop of aceto-carmine and pressed gently between folded filter papers. The cover glass was sealed with paraffin and stored overnight. To make the preparation permanent the paraffin was removed and the cover glass separated in a 1:1 mixture of acetic acid and n-butyl alcohol. The slide and the cover glass were then passed through n-butyl alcohol, 2 changes, and finally remounted in balsam.     

小麦籽粒铁、锌元素含量的研究进展

目前,铁、锌元素营养失衡已严重影响人类健康,而小麦(Triticum aestivum L.)作为人们主要的食物,其籽粒中铁、锌元素含量普遍较低。因此,通过小麦育种策略提高铁、锌元素含量则被认为是最经济有效的手段,这也引起了国内外学者的广泛关注。本文概述了小麦籽粒铁、锌元素含量的遗传差异、影响因素以及分子机理的研究现状,并展望了提高小麦籽粒铁、锌元素含量的研究前景及途径。     

The Development of Wheat Grain in Relation to Endogenous Growth Substances

Changes in the endogenous gibberellins and abscisic acid ofthe developing grains of Triticum aestivum L. have been studiedin relation to growth of the grain. The maximum grain volumeis inversely related to temperature and is reached while thedry weight is still small. This stage is associated with a sharpincrease in gibberellins. Starch formation is the principalfeature of the next stage of development and this ceases shortlyafter the beginning of a period of rapid water loss. This waterloss is preceded by an increase in the abscisic acid content.Changes in the endosperm are associated with changes in thebiochemical and physical attributes of the pericarp; these alsohave been correlated with changes in growth substances. Theresults are related to the ripening process and the final dryweight of the grain.     

Effects of Radiation and Temperature on Tiller Survival, Grain Number and Grain Yield in Winter Wheat

Effects of the environment on shoot survival were studied inwinter wheat cv. Avalon grown in microplots at a density of247 plants m^–2. The incident radiation and mean temperaturewere altered during one of three periods of between 14 and 29d duration, the first (P1) starting at the end of tiller productionand the last (P3) finishing near the end of the tiller deathphase, about three weeks before anthesis. Plants were giventemperature and radiation treatments in growth rooms in twoexperiments and extra light outdoors in a third experiment:they were at other times grown outdoors. Increasing radiation by between 60 and 100 per cent during P1had negligible effects on shoot number; during P2 it alwaysdelayed tiller death but increased final ear number in onlyone experiment; during P3 it consistently increased ear numberby up to 100 m^–2. Increased radiation always increasedcrop dry weight immediately after treatment but only sometimesdid this increase persist to maturity. Grain dry weight wasincreased by treatment during P3 of one experiment. Increasingthe temperature by 4 C decreased shoot number, usually onlytemporarily, by hastening death of some tillers. Warmer temperaturesdecreased crop growth after, but not during, treatment and decreasedgrain dry weight. Radiation and temperature rarely interacted. Variation in grain yield within and between experiments relatedwell to variation in number of grains m^–2, which in turnrelated to variation in ear dry weight at anthesis. Triticum aestivum L., wheat, radiation, temperature, tillers, grain yield, grain number     

Characterization of the Endoproteases Appearing during Wheat Grain Development

The pattern of endoproteolytic activities occurring during wheat (Triticum aestivum, cultivar Chinese Spring) grain development was investigated. Total endoprotease activity, assayed in solution with azocasein as a substrate, increased during the early stages of grain development to reach a maximum at 15 d postanthesis that was maintained until the grain was mature. Endoprotease activity was also assayed in gradient polyacrylamide gels co-polymerized with gelatin. The increase in endoproteolytic activity was due to the appearance of up to 18 endoproteolytic bands that were arbitrarily classified into five groups (A, B, C, D, and E). The presence of serine, aspartic, metallo, and, to a lesser extent, thiol proteases in developing wheat grains was demonstrated by the use of class-specific protease inhibitors. The appearance of the different classes of endoproteases during seed development was subject to temporal control; serine proteases were more abundant at early stages and aspartic and metallo proteases were more abundant at later stages. At intermediate stages of development (15-20 d postanthesis), most of the endoproteases were localized in the aleurone, testa, and embryo. The content of acidic thiol proteases was low in the developing starchy endosperm.     

药用植物种子休眠类型及休眠解除研究进展

种子休眠是植物在长期发育过程中形成的对不良环境条件主动适应的现象。介绍了常见药用植物种子休眠的原因,根据休眠原因对种子休眠与萌发的影响将种子休眠划分的几种类型,总结了对不同休眠类型的种子应分别采用的休眠解除方法,并评述了目前的研究进展。     

盐生植物种子的休眠、休眠解除及萌发的特点

本文讨论了盐生植物种子的休眠、休眠解除及萌发的特点,主要内容有：(1) 盐生植物种子的休眠类型;(2) 打破盐生植物种子休眠的必要条件;(3) 盐生种子萌发与土壤盐度的关系。并讨论了盐度抑制盐生植物种子的机理。最后,作者提出了将来研究盐生植物种子萌发需要解决的几个重点问题以及研究盐生植物种子休眠和萌发问题的意义。