Amino Acid Utilization in Seeds of Loblolly Pine during Germination and Early Seedling Growth (I. Arginine and Arginase Activity)

The mobilization and utilization of the major storage proteins in loblolly pine (Pinus taeda L.) seeds following imbibition were investigated. Most of the seed protein reserves were contained within the megagametophyte. Breakdown of these proteins occurred primarily following radicle emergence and correlated with a substantial increase in the free amino acid pool in the seedling; the majority of this increase appeared to be the result of export from the megagametophyte. The megagametophyte was able to break down storage proteins and export free amino acids in the absence of the seedling. Arginine (Arg) was the most abundant amino acid among the principal storage proteins of the megagametophyte and was a major component of the free amino acid pools in both the seedling and the megagametophyte. The increase in free Arg coincided with a marked increase in arginase activity, mainly localized within the cotyledons and epicotyl of the seedling. Arginase activity was negligible in isolated seedlings. Experiments with phenylphosphorodiamidate, a urease inhibitor, supported the hypothesis that arginase participates in Arg metabolism in the seedling. The results of this study indicate that Arg could play an important role in the nutrition of loblolly pine during early seedling growth.     

光和GA_3诱导番茄种子萌发过程中内源ABA的变化

外源GA_3和红光都能有效地诱导台湾红番茄种子萌发;外源ABA对光诱导萌发有明显的抑制作用。白光和红光诱导萌发过程中内源ABA水平急剧降低,而在黑暗或远红光下则一直保持在与风干种子中原有的高水平。1 mol/L HCl酸化1h后加100 ppm GA_3诱导萌发时内源ABA含量也随培养时间的延续而明显下降。     

Changes in Enzyme Levels During Germination of Seeds of Triticum durum

The changes in level of activity during the germination of wheat seedling (Triticum durum) in the dark have been investigated with 4 enzymes of glycolysis, 2 enzymes of the pentose phosphate shunt, 2 of the tricarboxylic acid cycle, 2 of amino acid metabolism and acid phosphatase. For some enzymes, which function in photosynthesis (fructose diphosphate aldolase, glyceraldehyde phosphate dehydrogenase NADP dependent), the level of activity was influenced by the presence of light.     

Changes in Seed Constituents During Germination and Seedling Growth of Precociously Matured Soybean Seeds(Glycine max)

During 7 d of precocious maturation of soybean seed (Glycinemax), the starch content declined and soluble sugar levels increasedin patterns similar to natural seed dehydration and maturation.Total seed protein content and total seed dry weight increasedwhereas oil content remained relatively unchanged. Overall,the proportions of the constituents in precociously maturedseeds were comparable to naturally mature seeds. Precociouslymatured soybean seeds showed much the same germination and seedlinggrowth frequency patterns as naturally matured seeds. Duringgermination and seedling growth of precociously matured seeds,starch, soluble sugar, protein and oil levels followed patternssimilar to naturally mature, germinating seeds and seedlings.Therefore, precocious maturation may be used as a model systemto investigate the control of the physiological and biochemicalevents occurring during seed maturation which lead to germinationand subsequently, seedling growth. Glycine max (L.) Merr., soybean, cotyledons, maturation, germination/seedling growth     

水稻种子萌发期间谷氨酰胺合成酶和NADH-谷氨酸合酶的变化

测定了水稻种子不同萌发时期胚乳、胚芽鞘和幼根的谷氨酰胺合成酶（GS）和依赖于NADH的谷氨酸合酶（NADH－GOGAT）活性变化。胚乳和胚芽鞘的GS活性在萌发过程中升高,幼根的GS活性则有所降低。NADH－GOGAT的活性变化趋势与GS相同。Native-PAGE活性染色表明,在萌发阶段的水稻种子胚乳和幼根里,始终只观察到一种GS活性带。但是,在水稻种子萌发3d后,在胚芽鞘中除继续检测到GS1的活性外,还可以观察到GS2的活性。蛋白质印迹显示,水稻种子胚乳中的GS（GSe)和GS1和GSra一样是一种胞质型GS。实验结果提示,这些不同组织中的GS与NADH－GOGAT构成的循环途径也许是水稻种子萌发时氨同化的主要途径。     

Episodic Growth and Relative Shoot: Root Balance in Loblolly Pine Seedlings

Leaf, root and stem systems of loblolly pine seedlings are characterizedby a seasonal periodicity in growth, during which they alternatein spurts of activity. Despite this periodicity, the allometriccoefficient describing the ratio of the relative growth ratesof leaf to root remains constant for at least the first twoyears of development. In part, constancy results from the inabilityof variation in the allocation of growth increment during briefperiods to change a pre-existing structure accumulated overthe life of the seedling. In addition, alternating periods ofleaf, root and stem growth may represent the action of feedbackmechanisms which operate to maintain an adaptive balance betweenorgan systems. Pinus taeda L., loblolly pine, allometric coefficient, homeostatic control of growth     

On the Germination and Changes in Chemical Composition During Seedling Emergence and Development of Cotton Seeds

Seeds from two cotton varieties attained similar maximum germinationpercentages at 30°C. Failure of germination occurred at15 and 45°C. At lower and higher temperatures than 30°Cmaximum germination percentages were lower and the periods beforegermination was intiated longer. Fumigation of seeds with methylbromide decreased their maximum emergence percentages in thefield, but dressing seeds with mercuric compounds had no effecton emergence. During the first 20 days of seed development theaccumulation of total dry-matter and oil was rapid and thenit continued at a steady and slower rate till day 52. A linearrelationship existed between the oil and residual dry-mattercontent of developing seeds. The disappearance of oil from thecotyledons of germinating seeds was gradual over the periodof 5 days of germination while that of starch was very rapidduring the first day, thereafter very little starch was mobilizedfrom the cotyledons to the embryo.     

油菜生长发育期间内源激素含量的变化

初花期至盛花期华双3号、华杂4号、恢5900等3个品种花蕾的iPAs含量呈明显上升趋势,而秦油2号则刚好相反(表2)。对双低品种华双3号功能叶的研究表明：苗期至盛花期IAA含量始终最高,其后依次是GA1 3;、iPAs、ABA。功能叶IAA的含量在越冬期处于整个生育期的最低水平,蕾薹期达到高峰,随后下降：GA1 3和iPAs含量随生育进程逐渐升高,并在初花期达到峰值;ABA在苗期及抽薹后一直处于很低水平,但在越冬期达到最高值(图1、2)。蕾薹期IAA主要分布在幼嫩和正在生长的器官中并起重要作用,而在功能叶中相对要少;幼叶GA1 3和iPAs含量最高,功能叶其次,花蕾最低(表1)。角果皮与籽粒的内源激素含量差异极显著,在开花后第39天,籽粒中IAA、GA1 3;、iPAs的含量大大超过角果皮(表3)。结果 表明iPAs在促进籽粒的充实饱满、物质积累转化方面发挥重要作用。     

Stored mRNA in Pine Seeds: Prolonged Preservation in Dry Seeds and Disappearance during Germination

RNA blot hybridization was performed with cDNA clones of storedmRNA in dry seed of Pinus thunbergii. The stored mRNA specieswere preserved in the dry seeds for at least 14 years. One ofthe mRNAs disappeared rapidly during germination, while otherswere detected until a late stage of germination. (Received August 19, 1991; Accepted February 26, 1992)     

Changes in Esters of Fatty Acids of Rhizopus arrhizus During Germination and Growth

Natural esters of fatty acids of Rhizopus arrhizus Fischer increased during the first 48 hr of growth. During the 48- to 72-hr period, there was a shift in concentration from the methyl esters to the ethyl esters of fatty acids.     

黄瓜种子萌发过程中Ca~(2 )分布的变化

采用细胞化学方法 ,研究了黄瓜种子中贮藏Ca2 的分布特点及其在萌发过程中的变化动态。干种子的子叶细胞中贮藏有大量的蛋白体、油脂体 ,Ca2 沉淀颗粒大量分布于胞质、胞间隙以及细胞质膜上。大多数蛋白体中有 1至数个圆球形或椭圆体形含Ca2 的球状晶体。相比之下 ,胚芽和胚根细胞中Ca2 较少。种子萌发早期 ,子叶中的贮藏钙及晶体溶解释放出的Ca2 部分转运到生长发育中的胚芽和胚根中。随着萌发的继续 ,胚根和胚芽细胞中的Ca2 不会持续增多 ,反而下降     

小麦种子成熟和萌发过程中的假萌发素活性

用SDS-PAGE方法研究了假萌发素(ψG)在小麦种子成熟和萌发过程中活性的变化.结果表明:在种子成熟过程中只有ψG表达,扬花后10 d,在颖壳、内外桴、种皮和果皮中皆可检测到ψG的草酸氧化酶活性,随着发育进程的推进,ψG的活性增大.在种子萌发过程中,在小麦品种中育5号的维管束过渡区中除了萌发素G和G'外,还可检测到ψG的草酸氧化酶活性.由于ψG在种子成熟过程中主要存在于颖壳、内外桴、果皮及种皮这些保护组织中,且开始大量表达的时间正是生长接近停止时,于是推测ψG很可能通过降解草酸产生H2O2而推动这些组织细胞壁的木质化.     

人工干燥和冷层积过程中的花楸树种子中内源激素含量变化

用高效液相色谱技术检测人工干燥和冷层积中花楸树种子中内源激素含量和平衡变化的结果表明:在人工干燥过程中种皮和胚内的GA3/ABA比值显著增高;2～5℃冷层积过程中的种皮内ABA含量显著下降,种皮和胚内各种促进生长类物质的相对含量(尤其是GA3/ABA比值)明显增加.     

Changes in Phenolic Inhibitors in Seeds of Acer saccharum during Stratification

Phenolics in sugar maple seeds were identified by colour reactions,u.v. spectroscopy and gas-liquid chromatography. Changes intheir inhibitory activity during stratification were also followedusing several bioassays. p-Coumaric, o-coumaric, and ferulicacids were found in all tissues. The highest concentrationswere noted in the embryonic axis and testa, but total amountsper fruit were highest in cotyledons and pericarp. p-Coumaricacid was the principal phenolic in dry seeds, and it declinedsubstantially in all tissues during the first half of stratificationwith little subsequent change thereafter. Decreases in o-coumaricand ferulic acids per seed were small by comparison, neverthelesslosses ranged between 36 and 68% of the original concentrations.Bioassays confirmed that the three endogenous phenolics possessedmarked inhibitory properties that diminished with the progressof stratilication, but only the compound identified as p-coumaricacid showed major inhibition in seed germination tests.     

Effect of Nitrogen Fertilization and Growth Suppression on Pitch Canker Development on Loblolly Pine Seedlings

One-yr-old loblolly pine seedlings of two half-sib families, grown in sand, were fertilized three times per week with nutrient solution containing 20 μg/ml (low) or 80 μg/ml (high) nitrogen. Nitrogen concentration in the nutrient solution was either constant throughout the experiment, or interehanged after the inoculation of stems or shoots with Fusarium subglutinans, 55 days after initiation of fertilization. Growth was suppressed by a weekly excision of shoots branching from the stem apex. Either high nitrogen nutrition or shoot excision generally enhanced canker elongation on stem inoculated plants; the combination of both was extremely conducive for disease development. With intact plants of family 8–68, interchange of pre-inoculation low nitrogen nutrition with high nitrogen after inoculation enhanced canker elongation and rate of wilt. Nitrogen content varied in wood, bark and needles, as well as with time intervals, but was consistently in accordance with nitrogen level in the nutrient solution. In shoot excised plants, nitrogen content was higher than in the respective treatment without shoot excision. The higher nitrogen nutrient accelerated disease development on inoculated shoots, compared to low nitrogen, on both pine families. With respective treatments, stem cankers were larger and rates of shoots exhibiting lesions or wilt were higher on plants of family 8–68 than on 8–61. It is postulated that the disease enhancing effect associated with higher nitrogen content in stem tissues results from an increased nitrogen availability to the pathogen.     

Changes in Endogenous Cytokinins of Lettuce Seed during Germination

Using the soybean callus bioassay it has been shown that dormant lettuce seeds (Lactuca sativa L. cv. Grand Rapids) contain large amounts of water soluble cytokinins and small amounts of butanol soluble ones. When the seeds are irradiated with red light, or imbibed with 5 mg/1 gibberellic acid in the dark, the total cytokinin content of the seeds decreases, the level of water soluble cytokinins decreases, and the level of the butanol soluble cytokinins increases. Far-red light does not reverse this effect completely although cytokinin activity in the butanol extracts decreases following such irradiation. It is proposed that the interconversion of cytokinins initiated by red light, or gibberellic acid in the dark, is one of the primary events leading to radicle elongation in light-sensitive lettuce seed.     

预浸和发芽过程中番茄种子细胞核的倍性变化

用细胞流检仪（ｆｌｏｗｃｙｔｏｍｅｔｅｒ）检测番茄种子细胞核倍性水平时发现：当年成熟的番茄种子胚细胞核ＤＮＡ绝大多数为２Ｃ水平,胚乳细胞核则为３Ｃ水平,说明成熟番茄种子细胞一般休止停留在Ｇ１期。同时我们也发现极少量的胚和胚乳细胞核分别为４Ｃ和６Ｃ水平,说明这些细胞已经进行了ＤＮＡ内复制。供试番茄种子浸种后１２ｈ左右完成吸水过程,２ｄ后胚根可突破种皮发芽。随着种子吸水过程的完成,胚根尖部分细胞开始进入ＤＮＡ复制期（Ｓ期）,而且此类细胞的数量增加迅速,一直到种子发芽。番茄胚根尖细胞进入４Ｃ的数量的多少与种子萌发时期有明显相关,４Ｃ／２Ｃ比率越大说明越接近发芽。渗控处理可以增加番茄种子胚根细胞４Ｃ／２Ｃ比率,因而明显提高种子的发芽速率。结果还表明;渗控处理的番茄种子再度干燥后４Ｃ／２Ｃ比率不变,这说明干燥可以固定细胞周期。     

Application of 31P NMR to Monitor Phosphorus Compounds and their Changes During Germination of Legume Seeds

Extracts of embryonic axes and cotyledons of 19 species of legumeswere analysed by ³¹P nuclear magnetic resonance; the effectof different extraction procedures on the solubilization ofthe several phosphocompounds was investigated. The contentsof phytic acid, inorganic phosphate, phosphomonoesters and phosphodiesterswere determined. The relative contents of these phosphocompoundswere very different when embryonic axes and cotyledons werecompared, and were greatly influenced by the taxonomic affiliationof the corresponding species. Phytic acid and inorganic phosphatewere by far the major phosphocompounds found in cotyledon extracts;an unusual phosphodiester component was detected only in embryonicaxes and was particularly abundant in species belonging to theLotoideae sub-family. The changes in the amount of the phosphodiestercompound were followed during germination and the results suggestthat it is not a phosphorus reserve. Furthermore, this componentwas preferentially present in the roots of the new plants. Itwas partially hydrolysed by RNAse and to a smaller extent byproteases, but not affected by DNAse. The hypothesis that thisunusual component might be a ribonucleoprotein is discussed. Key words: ³¹P NMR, legumes, seed components, phosphorus compounds, solubilization     

葡萄属种子发育的物候、萌发行为及其对冷层积的反应

以3个起源和分布中心的不同葡萄种及其杂交种作为实验材料,观察了开花、果实和种子成熟的物候,研究了成熟种子的基本特性和最初萌发率以及冷层积对成熟种子萌发的影响。结果表明,葡萄种子具有休眠特性,生理成熟时都具有分化完全的胚,在休眠解除过程中胚的形态不发生变化;美洲种休眠最深,欧亚种休眠最浅,其它种类的葡萄种子的休眠程度介于美洲种和欧亚种之间;不同种葡萄花期、果实和种子成熟过程的物候存在差异,果实成熟与种子成熟不同步,其间隔时间越短,种子休眠程度越深。冷层积60天能有效地解除东亚种、欧亚种、欧山杂种和蘡欧杂种的种子休眠,但对解除美洲种、美洲种种间杂种和欧美杂种的种子休眠效果较差。