皇后葵及香棕种子休眠机理与催芽技术探讨

本文以生产上发芽不整齐的皇后葵和香棕种子为材料,研究棕榈科植物种子的休眠机理及催芽技术。试验结果表明,皇后葵及香棕的果肉及胚乳中均含有发芽抑制物质,同一植株的种子发芽率及发芽力的差别还与种子的成熟度有关,用GA₃100mg/L或NAA 100mg/L浸种有利于提高发芽率。     

鹤顶兰种子萌发及原球茎增殖培养研究

以鹤顶兰成熟蒴果的种子为实验材料,研究影响种子非共生萌发的因素和种胚发育途径,并采用正交设计研究了原球茎增殖的影响因素。结果表明:冷藏影响种子的活力且其萌发率随冷藏时间延长而降低;0.5%NaClO溶液浸泡种子可提高萌发率,缩短初始萌发时间;种胚发育途径为种胚转绿后从种子侧面突破种皮而形成原球茎,随后分化出具根芽结构的完整植株;6-BA对原球茎增殖作用显著,原球茎增殖的最适培养基为1/2MS+3.0mg/L6-BA+1.0mg/L KT+1.0mg/L NAA,增殖倍数为6.67。     

Differentiation of a Functional Aleurone Layer Within the Seed Coat of Sinapis alba L.

The hitherto unresolved ontogenetic origin of the aleurone layerin mustard (Sinapis alba L.) seeds was investigated with lightand electron microscopy. Contrary to previous views, this layerof storage cells is neither derived from the endosperm nor fromthe nucellus, but from a particular cell layer within the innerintegument of the seed coat. These cells differentiate and becomefilled with storage protein and fat concurrently with the maturationof the embryo. They survive seed desiccation and become depletedof storage materials during seed germination. Temporally correlatedwith the germinating embryo, the aleurone cells produce microbodyenzymes, which are controlled by light in a similar fashionin both tissues. Sinapis alba L., mustard, aleurone layer, seed coat, seed formation, germination     

Distribution of Cadmium,Lead, Nickel,and Strontium in Imbibing Maize Caryopses

Seed germination is tolerant to heavy metals apparently because the seed coat is impermeable to metal ions. However, it is not clear whether the seed coat is a universal barrier for all metals. In addition, depending on their physical and chemical properties, a distribution of various metals may differ within an imbibing caryopsis, and therefore they produce dissimilar effects on seed germination. The toxic effects of Cd(NO₃)₂, Pb(NO₃)₂, Ni(NO₃)₂, and Sr(NO₃)₂ were estimated from the germination rates of maize (Zea mays L.) caryopses following two-day incubation with these salts. The distribution of heavy metals and Sr was studied by histochemical methods based on the formation of colored complexes with dithizone (Cd and Pb), dimethylglyoxyme (Ni), and sodium rhodizonate (Sr). Although the metals under study did not affect maize radicle protrusion, they inhibited seed germination in the following order: Cd > Ni ≈ Pb > Sr. Cd and Pb accumulated mainly in the seed coat cells, but Sr and Ni in the embryo cells and in the cells of endosperm (Sr) and scutellum (Ni). Although Cd was found only in the seed coat, it was the strongest inhibitor of seed germination. Apparently, due to high toxicity, Cd exerted its inhibitory effect at the concentrations too low for histochemical assay. In spite of easy translocation across the seed coat of imbibing caryopses, Sr did not considerably inhibit radicle protrusion and seed germination, apparently because of its low toxicity and predominant localization in the apoplast of embryo and endosperm cells.__________Translated from Fiziologiya Rastenii, Vol. 52, No. 4, 2005, pp. 635–640.Original Russian Text Copyright © 2005 by Seregin, Kozhevnikova.     

Seed Coat Dormancy in Two Species of Grevillea(Proteaceae)

The role played by the seed coat in seed dormancy of Grevillealinearifolia(Cav.) Druce and G. wilsonii(A. Cunn.) was testedby a series of manipulations in which the seed coat was dissectedand removed, dissected and returned to the decoated seed, ordissected, removed and given a heat shock, and returned to thedecoated seed. Germination of intact seeds of both species wasalso examined after exposure to heat shock, smoke, or heat shockand smoke combined. Water permeability of the seed coat wasinvestigated by examining imbibition. For intact seeds, virtuallyno germination occurred under any treatment (G. wilsonii), orgermination was increased by exposure to either heat or smoke(G. linearifolia). Removal of the seed coat led to germinationof all decoated seeds for G. linearifolia, or a proportion ofdecoated seeds for G. wilsonii. Inclusion of smoked water inthe incubation medium led to a higher proportion of decoatedseeds germinating for G. wilsonii. Returning the seed coat,either with or without heat shock to the seed coat, did notsignificantly affect germination in either species. Seed coatswere permeable to water in both species. For the two Grevilleaspecies, there were different dormancy mechanisms that werecontrolled by the seed coat (G. linearifolia) or by both theseed coat and embryo (G. wilsonii). Copyright 2000 Annals ofBotany Company Grevillea linearifolia, Grevillea wilsonii, dormancy, seed coat dormancy, seed coat permeability, smoke, heat shock, germination     

Effect of salinity on seed germination,growth and ion content in dimorphic seeds of Salicornia europaea L.(Chenopodiaceae)

The halophyte Salicornia europaea L. is a widely distributed salt-tolerant plant species that produces numerous dimorphic seeds. We studied germination and recovery in dimorphic seeds of Central Asian S. europaea under various salinity conditions. We also tested the effects of various salts on Natand Ktaccumulation during plant development from germination to anthesis under greenhouse conditions. We found good germination（close to control） of large seeds under Na Cl between 0.5 and 2%, Na₂SO₄and 2 Na Cl t KCl t Ca Cl between 0.5 and 3%, and 2Na₂SO₄t K₂SO₄t Mg SO4 between 0.5 and 5%. For the small seeds, we found stimulating effects of chloride salts（both pure and mixed） under 0.5e1% concentrations, and sulfate salts under 0.5e3%. Both types of seeds showed high germination recovery potential. Salt tolerance limits of the two seed types during germination and at the later stages of development were very similar（4e5%）. During plant growth the optimal concentrations of mixed chloride and sulfate salts ranged from 0.5 to 2%. The mechanisms of salt tolerance in the two seed types of S. europaea appear to differ, but complement each other, improving overall adaptation of this species to high salinity.     

卡德丽亚兰种子非共生萌发及萌发过程中原球茎发育的细胞学研究

对卡德丽亚兰种子非共生萌发条件及萌发过程中原球茎发育进行了研究。结果表明,低离子浓度培养基(KC、RE)利于卡德丽亚兰种子萌发;适宜种类和浓度的激素(1.0mg/LBA和0.1mg/LNAA或1.0mg/LKT和0.1mg/LNAA)对种子萌发有良好的促进作用。细胞学研究表明:卡德丽亚兰种子萌发过程的本质是未分化胚细胞团通过细胞的不断分裂形成原球茎,原球茎出现极性,随之分化形成芽端分生区,最终形成实生苗。     

Strategies for adaptation of Suaeda physophora, Haloxylon ammodendron and Haloxylon persicum to a saline environment during seed-germination stage

BACKGROUND AND AIMS: Germination is very important for plant establishment in arid regions. The strategies taken by halophytes during the seed germination stage to adapt to saline environments in an arid zone were investigated in Suaeda physophora (euhalophyte), Haloxylon ammodendron (xero-halophyte) and Haloxylon persicum (xerophyte). METHODS: Seeds of S. physophora, H. ammodendron and H. persicum were exposed to a range of iso-osmotic NaCl and PEG solutions. Seed germination in, and recovery germination from, high NaCl were recorded. The effects of iso-osmotic NaCl and PEG on seed water uptake and changes in ion content were measured. In addition, the structure of seeds and Na+ distribution in the seed coat and embryos of dry seeds were investigated. KEY RESULTS: The relative increase in fresh weight of germinating seeds was markedly reduced in -2.24 MPa PEG compared with that in -2.24 MPa NaCl, while the opposite trend was found in concentration of K+ during the initial 9 h for all species. Haloxylon ammodendron and S. physophora had a higher recovery germination from -3.13 MPa NaCl compared with H. persicum. Seeds of all species had no endosperm. More Na+ was compartmentalized in the seed coats of the two halophytic species compared with that in the xerophyte H. persicum. CONCLUSIONS: The effect of NaCl on seed germination was due to both osmotic stress and ion toxicity for the three species. High soil salinity and a high content of Na+ in seeds may induce more seeds to remain ungerminated in S. physophora and H. ammodendron. Morphological structure and adaptation to salinity during seed germination may determine the geographical distribution of H. ammodendron and S. physophora in certain saline regions.     

Seeds of Kosteletzkya virginica (Malvaceae): their structure,germination, and salt tolerance. II. Germination and salt tolerance

Kosteletzkya virginica (L.) Presl. (Malvaceae) is a perennial that grows in saline or brackish water, and is salt-tolerant in its mature state, but less tolerant during germination. The seeds show a very low permeability to water that increases during storage. The permeability to water differs in seeds harvested in different years. Optimal temperature for germination is 28–30 C. The effect of salinity on imbibition is largely osmotic, but germination is inhibited, apparently, by the combined osmotic and “ionic” effects, especially at high NaCl concentrations. Inhibition of germination by high NaCl concentrations is relatively more severe in scarified than in intact seeds, indicating that the seed coat acts as a partial barrier to Na⁺ influx. External application of proline or betaine did not improve germination under saline conditions. Dry seeds contain a significant amount of betaine and low levels of proline, but during germination and in the presence of NaCl the betaine content decreased while the proline content increased. Thus, the likely compatible solute in the germinating seed seems to be proline.     

Acid invertase in germinating Lactuca sativa seeds: Evidence for de novo synthesis

Acid invertase activity in germinating lettuce seeds is first observed after 15 hr germination, from when it rises steadily at least till 30 hr of germination. The enzyme was purified about 500-fold using ammonium sulphate fractionation followed by isoelectric focussing. Labelling the enzyme with ³⁵SO₄ or leucine-¹⁴C during development of its activity, followed by purification suggests that acid invertase is synthesized de novo during germination. The possible significance of acid invertase in the metabolism of the seed is discussed.     

Expression and inhibition of aquaporins in germinating Arabidopsis seeds

Extensive and kinetically well-defined water exchanges occur during germination of seeds. A putative role for aquaporins in this process was investigated in Arabidopsis. Macro-arrays carrying aquaporin gene-specific tags and antibodies raised against aquaporin subclasses revealed two distinct aquaporin expression programs between dry seeds and young seedlings. High expression levels of a restricted number of tonoplast intrinsic protein (TIP) isoforms (TIP3;1 and/or TIP3;2, and TIP5;1) together with a low expression of all 13 plasma membrane aquaporin (PIP) isoforms was observed in dry and germinating materials. In contrast, prevalent expression of aquaporins of the TIP1, TIP2 and PIP subgroups was induced during seedling establishment. Mercury (5 microM HgCl(2)), a general blocker of aquaporins in various organisms, reduced the speed of seed germination and induced a true delay in maternal seed coat (testa) rupture and radicle emergence, by 8-9 and 25-30 h, respectively. Most importantly, mercury did not alter seed lot homogeneity nor the seed germination developmental sequence, and its effects were largely reversed by addition of 2 mM dithiothreitol, suggesting that these effects were primarily due to oxidation of cell components, possibly aquaporins, without irreversible alteration of cell integrity. Measurements of water uptake in control and mercury-treated seeds suggested that aquaporin functions are not involved in early seed imbibition (phase I) but would rather be associated with a delayed initiation of phase III, i.e. water uptake accompanying expansion and growth of the embryo. A possible role for aquaporins in germinating seeds and more generally in plant tissue growth is discussed.     

种皮和环境温度对橡胶树种子萌发的影响

在人工气候箱控制的条件下,研究了种皮和环境温度对橡胶树(Hevea brasiliensis)种子萌发的影响.结果表明,种皮对橡胶树种子的吸水和萌发具有明显的机械限制作用;去除种皮后种子萌发速率加快,萌发指数增大,但萌发率从83.8%下降到47.8%,幼苗活力指数从332.3下降到187.9.15℃以下的温度明显推迟种子萌发,且萌发率下降.去除种皮后的种仁萌发率、萌发指数和幼苗活力指数均随着温度的升高而增大;有种皮种子的萌发率、萌发指数和幼苗活力指数分别在20℃(94.7%)、30℃(1.86)和25℃(374.4)时最大,而萌发速率系数随着温度的升高先增大后减小.在橡胶树栽培和胶园建设中,可利用种皮对种仁水分散失的限制作用以及对低温的不敏感性,有效延长橡胶树种子的贮藏时间,提高萌发率和籽苗质量.     

A study of the relationship between seedling characters and rate of germination within a seed lot

The relationship between seedling characters and germination rate within a seed lot was studied in cauliflower, leek and onion seeds. Newly germinated seeds were selected after successive days of imbibition at 20°C and placed on slope tests to assess early seedling growth. In all three species seedling length decreased and the coefficient of variation of those seedling lengths increased with increasing number of days of imbibition required for germination. Slow germinating seeds in all three species produced fewer normal healthy seedlings than faster germinating seeds. The relevance of these results to pre-germinated seed sowing techniques is discussed.     

Protein mobilization in germinating mung bean seeds involves vacuolar sorting receptors and multivesicular bodies

Plants accumulate and store proteins in protein storage vacuoles (PSVs) during seed development and maturation. Upon seed germination, these storage proteins are mobilized to provide nutrients for seedling growth. However, little is known about the molecular mechanisms of protein degradation during seed germination. Here we test the hypothesis that vacuolar sorting receptor (VSR) proteins play a role in mediating protein degradation in germinating seeds. We demonstrate that both VSR proteins and hydrolytic enzymes are synthesized de novo during mung bean (Vigna radiata) seed germination. Immunogold electron microscopy with VSR antibodies demonstrate that VSRs mainly locate to the peripheral membrane of multivesicular bodies (MVBs), presumably as recycling receptors in day 1 germinating seeds, but become internalized to the MVB lumen, presumably for degradation at day 3 germination. Chemical cross-linking and immunoprecipitation with VSR antibodies have identified the cysteine protease aleurain as a specific VSR-interacting protein in germinating seeds. Further confocal immunofluorescence and immunogold electron microscopy studies demonstrate that VSR and aleurain colocalize to MVBs as well as PSVs in germinating seeds. Thus, MVBs in germinating seeds exercise dual functions: as a storage compartment for proteases that are physically separated from PSVs in the mature seed and as an intermediate compartment for VSR-mediated delivery of proteases from the Golgi apparatus to the PSV for protein degradation during seed germination.     

The role of the seed coat in adaptation of dimorphic seeds of the euhalophyte Suaeda salsa to salinity

The role of the seed coat in adaptation of dimorphic seeds of the euhalophyte Suaeda salsa to salinity was investigated during germination and early seedling growth. Black and brown seeds were treated with chloroform for 1 min before the extract was used to analyze waxes and the seeds to investigate the protective role of the seed coat under saline conditions. Waxes in black seed coats were more abundant than those in brown seed coats. Salinity (500 mM NaCl) increased the concentration of Na⁺ and decreased the concentration of K⁺ in both black and brown seeds regardless of chloroform treatment. Chloroform treatment alone (in the absence of NaCl) had no effect on the concentration of Na⁺ or K⁺ in black or brown seeds and in the presence of 500 mM NaCl had no effect on the concentration of Na⁺ or K⁺ in brown seeds. However, chloroform treatment increased Na⁺ and decreased K⁺ in black seeds with 500 mM NaCl. A change of MDA (malondialdehyde) concentration in black and brown seeds treated with or without chloroform was similar to the change of Na⁺ concentration. High salinity (1500 mM NaCl) pretreatment for 40 days had a less adverse effect on germination of black seeds compared with brown seeds after they were transferred to fresh water regardless of chloroform treatment. Similar results were found for seedling emergence. In conclusion, a black seed coat may be more protective than a brown seed coat, probably by shielding the embryo from ion toxicity, because of its higher content of waxes. Thus black seeds can better maintain seed viability than brown seeds for extended periods under hypersaline conditions.     

掌叶木种皮障碍及种子各部位内源抑制活性的研究

掌叶木(Handeliodendron bodinieri)是残遗于中国的稀有单种属植物,因人为破坏、生境特殊及自身特性的影响,资源稀少,被列为国家一级重点保护野生珍稀濒危植物。该研究以掌叶木种子为材料,研究了4种不同发芽条件下(带种皮、浓硫酸处理种皮、完全去除种皮、仅露出胚根)种子萌发性、种皮透水性、掌叶木果皮、假种皮、种皮和种仁四个部位不同浓度甲醇浸提物(0、3.125、6.25、12.5、25 mg/m L)对白菜种子萌发及幼苗生长的影响以及掌叶木各部位浸提物对种子萌发的影响。结果表明:(1)掌叶木种皮具有一定的透水性,为掌叶木种子的萌发提供必要的透水透气条件,不影响种子萌发前的水分吸收,但掌叶木种皮的机械阻碍、易霉变对种子的萌发影响较大。(2)掌叶木的果皮、假种皮、种皮和种仁甲醇浸提物对白菜种子的萌发和生长都有影响,尤其对白菜幼根的生长有较强的抑制作用,抑制强度依次是种仁果皮假种皮种皮,且随着浓度的升高,抑制作用增强。该研究结果揭示了掌叶木种子难发芽、发芽率低的原因,为掌叶木的人工扩繁和保护与利用奠定了基础。     

赤霉素对紫斑牡丹种子下胚轴萌发及其种皮和胚乳结构的影响

以紫斑牡丹种子为试验材料,考察不同浓度赤霉素(GA_3)处理下种子生根情况,同时对其种皮纹饰进行了扫描电镜(SEM)观察,并对胚乳结构进行了荧光倒置显微镜、透射电镜(TEM)观察,以揭示GA_3对紫斑牡丹种子下胚轴解除休眠过程中种子种皮、胚乳结构变化和生根的影响。结果表明:(1)GA_3处理能够促进紫斑牡丹种子生根,以300 mg/L GA_3处理的种子生根效果最好,与对照相比可提前14.66 d生根,生根率可达62.33%。(2)扫描电镜观察发现,紫斑牡丹种皮表面含有蜡质,种子萌发进程中蜡质明显不断增加,种皮表面网眼逐渐消失,种皮皱缩明显。(3)光学显微镜观察发现,GA_3处理的紫斑牡丹种子胚乳细胞中含有较多淀粉体和蛋白体,并随着种子萌发进程逐渐积累,可为种子萌发提供足够的养分。(4)透射电镜观察发现,GA_3处理的紫斑牡丹种子胚乳细胞内大分子营养物质不断降解,线粒体、内质网、高尔基体等细胞器相继出现,种子下胚轴休眠解除,细胞壁较薄后期消融,利于营养物质传送。研究认为,适宜浓度GA_3处理可有效加快紫斑牡丹种皮结构的改变和胚乳细胞内物质代谢进程,促进种子萌发,且300 mg/L GA_3处理紫斑牡丹种子24 h可以获得最好的生根效果。     

四种石斛兰种胚发育进程研究

以玫瑰石斛、尖刀唇石斛、短棒石斛、兜唇石斛种子为材料,进行种胚非共生萌发研究,并对其种子形态和胚的发育进程进行了显微观察。结果表明:处于球形胚阶段的石斛兰种子,种胚吸胀后突破种皮,发育至吸收毛和芽生长点出现后,种胚形成原球体;种子萌芽后胚尚未成熟,只进入心形胚阶段。呈纺锤形种子的种皮两端形状不同,一端存在结点,呈弯曲状的尖形,另一端种皮呈收拢的圆口形。4种石斛兰种子,玫瑰石斛种子最长,为两端狭长的纺锤形;兜唇石斛种子最短,呈两端稍细的纺锤形。玫瑰石斛、短棒石斛、尖刀唇石斛种子胚培养需要5～10 d萌发;兜唇石斛种子和胚皆偏小,萌发需要30 d。石斛兰种胚和种皮吸水膨胀后,种胚向种皮的一端移动、脱出或种胚撕裂种皮中央后突破而出,形成裸胚。玫瑰石斛种子撕裂种皮后主要从种皮中央突破;短棒石斛、尖刀唇石斛、兜唇石斛部分种胚从种皮一端脱出,部分种胚则从中央撑破种皮脱出。充分膨胀、变绿后萌芽的裸胚,存在极性,顶部芽生长点萌动,下部出现成群散射状吸收毛。     

Release of reactive oxygen intermediates (superoxide radicals, hydrogen peroxide, and hydroxyl radicals) and peroxidase in germinating radish seeds controlled by light, gibberellin, and abscisic acid

Germination of radish (Raphanus sativus cv Eterna) seeds can be inhibited by far-red light (high-irradiance reaction of phytochrome) or abscisic acid (ABA). Gibberellic acid (GA3) restores full germination under far-red light. This experimental system was used to investigate the release of reactive oxygen intermediates (ROI) by seed coats and embryos during germination, utilizing the apoplastic oxidation of 2',7'-dichlorofluorescin to fluorescent 2',7'-dichlorofluorescein as an in vivo assay. Germination in darkness is accompanied by a steep rise in ROI release originating from the seed coat (living aleurone layer) as well as the embryo. At the same time as the inhibition of germination, far-red light and ABA inhibit ROI release in both seed parts and GA3 reverses this inhibition when initiating germination under far-red light. During the later stage of germination the seed coat also releases peroxidase with a time course affected by far-red light, ABA, and GA3. The participation of superoxide radicals, hydrogen peroxide, and hydroxyl radicals in ROI metabolism was demonstrated with specific in vivo assays. ROI production by germinating seeds represents an active, developmentally controlled physiological function, presumably for protecting the emerging seedling against attack by pathogens.     

新疆干旱区植物藜的种子异型性及其萌发机理

新疆干旱区分布的植物藜(Chenopodium album)的种子有黑色和褐色两种类型。对藜的异型性种子从形态结构、不同环境因素及激素或化学物质对萌发的影响以及同工酶谱等方面进行了研究,并对其萌发及适应异质环境的机理进行了讨论。结果表明:(1)藜的异型性种子在形态结构、萌发休眠特性等方面都存在明显差异:黑色种子种皮厚且硬,休眠,萌发慢,萌发率低;褐色种子种皮薄而软,不休眠,萌发快且萌发率高;(2)黑色种子的休眠可通过切除胚根外缘种皮得以完全解除;(3)赤霉素、乙烯利对黑色种子的萌发无明显促进作用;KNO3可较显著促进黑色种子的萌发;协同使用乙烯利和KNO3时,可显著提高黑种子萌发率,完全打破休眠;(4)黑色种子和褐色种子的酯酶、过氧化物酶及过氧化氢酶同工酶谱带存在差异;(5)黑色种子的萌发需要光照,而褐色种子则对光不敏感;低温贮藏对二者的萌发均无显著影响,尽管黑色种子的萌发率有波动。研究结果初步显示黑色种子的休眠是内源(胚)和外源(种皮)因素共同所致。藜的种子异型性及其萌发机理的形成是其对新疆干旱区异质化环境的高度适应。