共查询到20条相似文献,搜索用时 15 毫秒
1.
ANDREA SCHATRAL 《Botanical journal of the Linnean Society. Linnean Society of London》1995,119(3):257-263
The internal structure of the seed was studied for four Western Australian species of the genus Hibbertia (Fam.: Dilleniaceae). The principal mechanical layer of the seed coat is the endotesta. The large cells of the endotesta are heavily cutinized in potentially viable seeds of all examined species. However, results for H. hypericoides show that the cells of the endotesta are distinctly less cutinized in non-viable seeds. The tegmen consists of only one layer which is spirally thickened. Remains of the nucellus enclose the endosperm. The endosperm is rich in both starch and lipids, and the embryo is underdeveloped and minute. 相似文献
2.
3.
4.
JUAN CARLOS LÓPEZ-ALMANSA EDWARD C. YEUNG LUIS GIL 《Botanical journal of the Linnean Society. Linnean Society of London》2004,145(4):455-467
Three genotypes of field elm ( Ulmus minor ) were studied to determine the structural basis of seed abortion in this species. In the non-abortive control, P-VV1, the pattern of seed development is similar to many flowering plants. The embryo progresses through defined morphological stages leading to developmental arrest as the seed matures. Storage products are abundant within embryo cells. Endosperm development is similar to the nuclear type; however, a more extensive cellularization of the endosperm occurs prior to it being crushed by the expanding embryo. For the abortive genotypes, M-SF1 and V-JR1, abnormalities in endosperm development are found. This is judged by the early cellularization and the massive synthesis of the PAS-positive material in the cellular endosperm. In these abortive genotypes, embryo development is delayed and storage products failed to accumulate within embryo cells. After seed desiccation, no living embryo tissue remains within the seed coat in the abortive genotypes. © 2004 The Linnean Society of London, Botanical Journal of the Linnean Society , 2004, 145 , 455–467. 相似文献
5.
BACKGROUND: In angiosperms the seed is the outcome of double fertilization, a process leading to the formation of the embryo and the endosperm. The development of the two seed compartments goes through three main phases: polarization, differentiation of the main tissues and organs and maturation. SCOPE: This review focuses on the maize kernel as a model system for developmental and genetic studies of seed development in angiosperms. An overview of what is known about the genetic and molecular aspects underlying embryo and endosperm formation and maturation is presented. The role played by embryonic meristems in laying down the plant architecture is discussed. The acquisition of the different endosperm domains are presented together with the use of molecular markers available for the detection of these domains. Finally the role of programmed cell death in embryo and endosperm development is considered. CONCLUSIONS: The sequence of events occurring in the developing maize seed appears to be strictly regulated. Proper seed development requires the co-ordinated expression of embryo and endosperm genes and relies on the interaction between the two seed components and between the seed and the maternal tissues. Mutant analysis is instrumental in unravelling the genetic control underlying the formation of each compartment as well as the molecular signals interplaying between the two compartments. 相似文献
6.
7.
异子蓬(Borszczowia aralocaspica)为中亚荒漠特有种,在我国仅分布于新疆,其果实具有二型性。对同一生长地2006、2007、2008年异子蓬种子的大小、萌发特性及结实格局进行比较,结果表明:(1)年份和种子类型对种子大小和重量均有显著影响(P<0.05)。(2)2种类型种子具有不同的萌发行为,褐色种子萌发率高(>90%),萌发速度快,而黑色种子萌发率低(2006年的萌发率为31%),萌发速度慢;2种类型种子的萌发指数在不同年际间均差异显著。(3)不同年际间,种子总数、褐色种子数、黑色种子数均具有极显著差异(P<0.001),且随个体的增大黑色种子的比例逐渐减小,褐色种子的比例逐渐增大,并且黑色种子数目均高于褐色种子数目。该研究为深入认识异型种子的生态适应对策提供理论基础。 相似文献
8.
Seed development depends on coordination among embryo, endosperm and seed coat. Endosperm undergoes nuclear division soon after fertilization, whereas embryo remains quiescent for a while. Such a developmental sequence is of great importance for proper seed development. However, the underlying mechanism remains unclear. Recent results on the cellular domain- and stage-specific expression of invertase genes in cotton and Arabidopsis revealed that cell wall invertase may positively and specifically regulate nuclear division of endosperm after fertilization, thereby playing a role in determining the sequential development of endosperm and embryo, probably through glucose signaling. 相似文献
9.
10.
11.
12.
为明确黄土丘陵沟壑区植物种子库如何调控种子萌发来提高个体适合度,选择研究区7种具有种子库的主要物种为研究对象,以刚成熟和室内储存种子为对照,比较植冠宿存(5个宿存期)和土壤埋藏(5a埋藏期)对植物种子萌发特性的影响,探讨植冠种子库与土壤种子库储存下的种子萌发策略。结果表明:7种植物种子经过不同种子库储存后萌发特性表现出明显的种间差异,黄刺玫(Rosa xanthina)和水栒子(Cotoneaster multiflorus)种子萌发力表现为植冠宿存不变型、土壤储存增强型,土壤储存明显提高水栒子种子萌发速率;达乌里胡枝子(Lespedeza davurica)和狼牙刺(Sophora davidii)种子萌发力表现为植冠宿存增强型、土壤储存减弱型,种子萌发历时表现为植冠宿存延长型,土壤种子库储存还可加快达乌里胡枝子萌发速率、缩短萌发历时;茭蒿(Artemisia giralaii)和铁杆蒿(Artemisia gmelinii),种子萌发率随植冠宿存时间先升高后降低,随土壤储存时间先降低后升高,土壤储存可推迟其萌发,铁杆蒿种子萌发速率在植冠与土壤储存后均加快;紫丁香(Syringa oblata)种子萌发率随植冠宿存先升高后降低,土壤储存明显加快其种子启动萌发与速率。在黄土丘陵沟壑区,植物种子经过植冠或土壤种子库储存,或增加、加快、提早萌发充分利用有利条件提高占据性,或减少、减缓、推迟萌发分摊不利条件的风险;而且该区植物植冠与土壤储存后种子萌发特性间的关系,体现各自适应环境与应对干扰的分工与协作策略,主要表现为:单一主导型和相辅相成型。 相似文献
13.
Seed banks and sexual reproduction are known to be significant in colonization and re-establishment of some aquatic macrophyte communities. For highly clonal aquatic macrophytes, however, there is a lack of information on seed production and seed fate as compared with annual sexual species. The seed bank for three populations of Vallisneria americana in the Huron-Erie corridor of the Great Lakes was sampled and quantified in the spring of 1994, and related to seed production in the previous season at these sites. Seed deposition rates during 1994 were also assessed. Sites varied in the proportion of plants flowering and in their tertiary sex ratios, but did not differ in seed numbers produced per unit area. The size of the seed bank was not significantly related to the previous season's seed output, and estimates of seed deposition in the following year tended to be approximately tenfold greater than seed densities found in the seed bank. The stages between seed production and subsequent seed germination are generally very dynamic, with dispersal, mortality, and predation as likely regulating factors. The potential for seedling establishment in V. americana needs to be assessed more fully before the role of seeds in population processes can be determined. 相似文献
14.
Andrew B. Gipson Kyla J. Morton Rachel J. Rhee Szabolcs Simo Jack A. Clayton Morgan E. Perrett Christiana G. Binkley Erika L. Jensen Dana L. Oakes Matthew F. Rouhier Kerry A. Rouhier 《The Plant journal : for cell and molecular biology》2017,90(6):1029-1039
We have functionally characterized the role of two putative mitochondrial enzymes in valine degradation using insertional mutants. Prior to this study, the relationship between branched‐chain amino acid degradation (named for leucine, valine and isoleucine) and seed development was limited to leucine catabolism. Using a reverse genetics approach, we show that disruptions in the mitochondrial valine degradation pathway affect seed development and germination in Arabidopsis thaliana. A null mutant of 3‐hydroxyisobutyryl‐CoA hydrolase (CHY4, At4g31810) resulted in an embryo lethal phenotype, while a null mutant of methylmalonate semialdehyde dehydrogenase (MMSD, At2g14170) resulted in seeds with wrinkled coats, decreased storage reserves, elevated valine and leucine, and reduced germination rates. These data highlight the unique contributions CHY4 and MMSD make to the overall growth and viability of plants. It also increases our knowledge of the role branched‐chain amino acid catabolism plays in seed development and amino acid homeostasis. 相似文献
15.
以吉林珲春自然群落的野生玫瑰(Rosa rugosa Thunb.)为试验材料,探究野生玫瑰在果实形成过程中种子的发育及休眠性的形成和变化。选取青果期(1~35 d)、转色期(35~60 d)、红果期(60~75 d)的果实及种子,结合形态学、组织细胞学观察法及高效液相色谱技术,对果实各发育时期的种子形态、种胚及内果皮的发育进行研究,并分析种子内源激素含量变化与果实发育、种子休眠之间的关系。结果表明:果实和种子在青果期(1~35 d)时发育速度最快,种胚在花后24 d发育完全,种子不存在形态休眠。花后24 d内果皮开始沉积木质素并逐渐木质化,种子开始产生机械休眠。种子激素含量的变化与果实的发育、转色及内果皮的木质化密切相关,种子内源GA3和ABA含量在青果期(1~35 d)达到峰值,内源IAA含量在果实转色期(35~60 d)达到最大值,高浓度的ABA含量是种子尚未脱离果实时便已进入生理休眠的主要原因。 相似文献
16.
Antony M. Chettoor Allison R. Phillips Clayton T. Coker Brian Dilkes Matthew M. S. Evans 《Genetics》2016,204(1):233-248
Flowering plants, like placental mammals, have an extensive maternal contribution toward progeny development. Plants are distinguished from animals by a genetically active haploid phase of growth and development between meiosis and fertilization, called the gametophyte. Flowering plants are further distinguished by the process of double fertilization that produces sister progeny, the endosperm and the embryo, of the seed. Because of this, there is substantial gene expression in the female gametophyte that contributes to the regulation of growth and development of the seed. A primary function of the endosperm is to provide growth support to its sister embryo. Several mutations in Zea mays subsp. mays have been identified that affect the contribution of the mother gametophyte to the seed. The majority affect both the endosperm and the embryo, although some embryo-specific effects have been observed. Many alter the pattern of expression of a marker for the basal endosperm transfer layer, a tissue that transports nutrients from the mother plant to the developing seed. Many of them cause abnormal development of the female gametophyte prior to fertilization, revealing potential cellular mechanisms of maternal control of seed development. These effects include reduced central cell size, abnormal architecture of the central cell, abnormal numbers and morphology of the antipodal cells, and abnormal egg cell morphology. These mutants provide insight into the logic of seed development, including necessary features of the gametes and supporting cells prior to fertilization, and set up future studies on the mechanisms regulating maternal contributions to the seed. 相似文献
17.
濒危植物明党参种子散布和种子库动态研究 总被引:19,自引:0,他引:19
对伞形科濒危植物明党参(Changium smyrnioides)的种子生产、散布和种子库动态进行了研究。明党参平均每株产生完好种子132粒,86.36%来自顶生花序,不同生境中个体产生的种子千粒重有差异;其平均1.06m高的花葶在种子散布过程中易倒伏,使种子远离母株;种子散布格局为聚集型;种子库密度随时间逐渐下降。明党参种子产量和不同时期种子库密度均低于同科非濒危植物峨参(Anthriscus sylvestris),2个种的种子库均为非持续型;明党参具有低种子数、大粒种子、种子散布远离母株以减少种内竞争的K对策,在受到人类大量采挖和生境干扰后种群不容易迅速恢复;而峨参采取高种子数、小粒种子、种子近母株密集分布和产生无性系的r对策,种群受干扰后易恢复。 相似文献
18.
Olga A. Kildisheva Kingsley W. Dixon Fernando A. O. Silveira Ted Chapman Alice Di Sacco Andrea Mondoni Shane R. Turner Adam T. Cross 《Restoration Ecology》2020,28(Z3):S256-S265
From 50 to 90% of wild plant species worldwide produce seeds that are dormant upon maturity, with specific dormancy traits driven by species' occurrence geography, growth form, and genetic factors. While dormancy is a beneficial adaptation for intact natural systems, it can limit plant recruitment in restoration scenarios because seeds may take several seasons to lose dormancy and consequently show low or erratic germination. During this time, seed predation, weed competition, soil erosion, and seed viability loss can lead to plant re‐establishment failure. Understanding and considering seed dormancy and germination traits in restoration planning are thus critical to ensuring effective seed management and seed use efficiency. There are five known dormancy classes (physiological, physical, combinational, morphological, and morphophysiological), each requiring specific cues to alleviate dormancy and enable germination. The dormancy status of a seed can be determined through a series of simple steps that account for initial seed quality and assess germination across a range of environmental conditions. In this article, we outline the steps of the dormancy classification process and the various corresponding methodologies for ex situ dormancy alleviation. We also highlight the importance of record‐keeping and reporting of seed accession information (e.g. geographic coordinates of the seed collection location, cleaning and quality information, storage conditions, and dormancy testing data) to ensure that these factors are adequately considered in restoration planning. 相似文献
19.
The 20S proteasome from wheat ( Triticum aestivum L., Yangmai 158) endosperm was purified to apparent homogeneity by three sequential centrifugations and gradient PAGE (GPAGE). The purified 20S proteasome clearly cleaved peptidyl-arylamide bonds in the model synthetic substrates Z-GGL-AMC and Z-GGR-AMC, which are used to reflect chymotrypsin-like and trypsin-like activity, respectively. For both substrates, the optimum pH was 8.0, but the optimum temperatures for chymotrypsin-like and trypsin-like activity were 55 °C and 37 °C, respectively. Both enzyme activities were clearly inhibited by MG115 and PMSF. Polyubiquitinated proteins remained constant from 0 to 7 days after seed imbibition, but caseinolytic activity and the amount of the 20S proteasome associated with the aleurone layer decreased from 1 to 2 days after imbibition (DAI), then increased from 2 to 4 DAI, and reached a maximum at 4 DAI that was retained until 7 DAI. An increase was seen in the mRNA level of the β5 subunit of the 20S proteasome from 2 DAI, and caseinolytic activity and the amount of the 20S proteasome increased from 3 DAI onwards. In addition, the main storage proteins of the wheat endosperm could not be hydrolyzed by the 20S proteasome. The evidence suggests that the main role of the 20S proteasome may not be to degrade massive proteins of the wheat endosperm after seed imbibition. 相似文献
20.
Aims In most natural plant populations, there is a strong right-skewed distribution of body sizes for reproductive plants—i.e. the vast majority are relatively small, suppressed weaklings that manage not just to survive effects of crowding/competition and other hazards but also to produce offspring. Recent research has shown that because of their relatively large numbers, these relatively small resident plants collectively contribute most of the seed offspring production available for the population in the next generation. However, the success of these offspring will depend in part on their quality, e.g. reflected by seed size and resource content. Accordingly, in the present study, we used material from natural populations of herbaceous species to test the null hypothesis that there is no significant relationship between body size variation in resident plants—resulting from between-site variation in the intensity of crowding/competition—and variation in the mass or N content of their individual seeds.Methods Using populations of 56 herbaceous species common in eastern Ontario, total above-ground dry plant mass, mean mass per seed and mean nitrogen (N) content per seed were recorded for a sample of the largest resident plants and also for the smallest reproductive plants growing in local neighbourhoods with the most severe crowding/competition from near neighbours.Important findings Mass per seed was numerically smaller from the smallest resident plants for most study species, but with few exceptions, this was not significantly different (P> 0.05) from mass per seed from the largest resident plants. The results therefore showed no general effect of maternal plant body size on individual seed mass, or N content. This suggests that the reproductive output of the smaller half of the resident plant size distribution within these populations is likely to contribute not just most of the seed production available for the next generation but also seed offspring that are just as likely—on a per individual basis—to achieve seedling/juvenile recruitment success as the seed offspring produced by the largest resident plants. This conflicts with the traditional 'size-advantage' hypothesis for predicting plant fitness under severe competition, and instead supports the recent 'reproductive-economy-advantage' hypothesis, where competitive fitness is promoted by capacity to produce offspring that—despite severe body size suppression imposed by neighbour effects—in turn have capacity to produce grand-offspring. 相似文献