Germination Promotion of Loblolly Pine and Baldcypress Seeds by Stratification and Chemical Treatments

The effects of 4 chemicals on the germination promotion of stratified and unstratified seeds of loblolly pine (Pinus taeda) and baldcypress (Taxodium distichum) were studied. The chemicals used were gibberellic acid, kinetin, potassium nitrate and thiourea, each at 3 different concentrations. Stratification promoted the germination of both seed species. Certain concentrations of gibberellic acid, potassium nitrate and thiourea improved the germination of unstratified loblolly pine and baldcypress seeds while kinetin had no stimulatory effect. All 4 chemicals at specific concentrations promoted the germination of loblolly pine seeds stratified for a short period of time. Considering both speed and completeness of germination, best results were obtained when 21-day stratified seeds were treated with either gibberellic acid (100 mg/1) or kinetin (10 mg/1). In baldcypress, on the other hand, none of these chemicals had any stimulatory effect on the germination of stratified seeds. Germination of both species of seeds was either partially or completely inhibited by the highest concentration of thiourea (30,000 mg/1) used.     

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。     

胡杨种子萌发过程中几种相关酶的活性变化

在室温条件下,胡杨种子保留冠毛贮藏可适当延长其生命力;室温贮藏带冠毛的胡杨种子,前20 d萌发率降低幅度不大.随着种子贮藏时间的延长,过氧化物酶(POD)、过氧化氢酶(CAT)和超氧化物歧化酶(SOD)活性均先上升后下降,峰值出现时间与种子室温贮藏20 d相对应;脱氢酶活性先上升后下降再回升,峰值出现时间也与种子室温贮藏20 d相对应;酸性磷酸酯酶(ACP)活性与种子萌发率同步下降.室温贮藏40 d的带冠毛胡杨种子仍有22.3%的萌发率.     

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.     

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     

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 Peroxidase Activity Associated with Cell Walls During Pine Hypocotyl Growth

Peroxidase active against 2,2'-azino-bis-[3-ethylbenzthiazoline-6-sulphonicacid] (ABTS) and guaiacol were found in the apoplastic fluid,as well as ionically and covalently associated with pine cellwalls. The highest activity was found covalently bound to cellwalls, while the lowest activity was in the apoplastic fluid.Both ABTS and guaiacol peroxidases increased with the hypocotylage in the three fractions, apoplastic, ionically and covalentlybound. Furthermore, the changes in both peroxidases along thehypocotyl were also studied. Both apoplastic ABTS- and guaiacol-peroxidasesincreased from the apical towards the basal region of the hypocotylsof 10-d-old seedlings. A relation between peroxidase activityin the apoplastic fluid and the cell wall stiffening in pinehypocotyls is proposed.Copyright 1995, 1999 Academic Press Cell wall, growth, hypocotyl, peroxidase, pine, Pinus pinaster Aiton     

Alkaloid Changes in Tobacco Seeds during Germination

Nicotine, nornicotine, anabasine, and anatabine, normally found in growing and mature tobacco (Nicotiana tabacum L.) plants, were extracted and quantified from mature tobacco seeds and young tobacco seedlings. The rate of net alkaloid disappearance and accumulation in tobacco seedlings was related to phases of germination.     

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.     

Metabolism of C-Maltose in Avena fatua Seeds During Germination

Non-dormant and dormant seeds of Avena fatua metabolize ¹⁴C-maltose in different ways: in non-dormant seeds, ¹⁴C-maltose administered to the endosperm is readily converted to sucrose in the scutellum and translocated to the embryo; in dormant seeds, little sucrose is synthesized from ¹⁴C-maltose, and maltose and glucose tend to accumulate in the endosperm. It is suggested that biosynthesis of sucrose is essential for effective transport of the endosperm reserve to the embryonic axis in germinating seeds.     

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.