绞股蓝果实的发育解剖学研究

应用石蜡切片和扫描电镜的方法,观察了绞股蓝果实与种子的发育过程,结果表明:花后12 d左右,绞股蓝合子开始进行第一次分裂,极核分裂在花后6～7 d,核型胚乳在胚的发育中被吸收,胚的发育为茄型,外珠被呈网格状花纹。假果,表面有蜡质,果壁可明显分为3层,内侧细胞后期解体,种子倒三角形,表面瘤状突起。脱落花果的结构表现为珠被萎缩和胚发育受阻。     

Endosperm and Embryo Development in Daucus carota L.

Maximum carrot seed dry weight and maximum endosperm volumewere reached about 35 d after anthesis, although at this timethe endosperm was still soft, the pericarp green and less than50% of the seeds were viable. Fully viable, ripe seeds werenot produced until 44 d later. Seventy per cent of the increasein endosperm volume was due to an increase in cell number, whichceased 35 d after anthesis. The increase in embryo volume wasslower and was due to an increase in both cell number and cellvolume which continued until 49 d after anthesis. At maturitythe embryo was the equivalent of between 2% and 3% of the endospermvolume. The relationship between embryo length and cell number per embryowas unaffected by seed crop plant density, seed crop harvestdate and position of the seed on the mother plant but it wasaffected by the year of seed production, possibly due to differencesin temperature during the period of seed growth. Key words: Endosperm, Embryo, Carrot, Development     

The quantitative estimation of the infection of bean seed with Pseudomonas phaseolicola (Burkh.) Dowson

A routine laboratory method for the detection of Pseudomonas phaseolicola in bean seed is described. The method will detect low levels of seed-borne infection and has been used in a statistical procedure (the most probable number method) to give an estimate of percentage infection. Infection in seeds harvested from heavily infected crops varied from 10 to 1%, compared with from 1% to less than 0.1% in commercial seed stocks. A high proportion of infected seeds failed to produce infected plants and this may account for the very low levels of primary infection reported in the field. Removal of seeds showing possible ‘symptoms’ of disease reduced, but did not eliminate, infection from seed stocks.     

Effects of the pericarp on imbibition,seed germination,and seedling establishment in seeds of <Emphasis Type="Italic">Hedysarum scoparium</Emphasis> Fisch. et Mey

Four independent experiments were designed to investigate the effects of the pericarp on seed imbibition, dehydration, germination, seedling establishment, and seed longevity in the field in seeds of Hedysarum scoparium Fisch. et Mey. The results showed that the presence of the pericarp decreased seed imbibition rates in the first 6 h, but the seeds attained significantly higher final water content after 24 h of soaking. The pericarp caused seed dormancy, and removal of the pericarp improved the germination percentage to 90 from 44%. In the pot experiment, where the level of moisture was maintained at field capacity (control), seeds with the pericarp removed had significantly improved seedling establishment. However, no statistical differences were observed in seedling establishment when the experiment was repeated under dry conditions at 40% of the field water capacity. The seedling biomass derived from seeds without the pericarp was much higher in the control but the trend was reversed under dry conditions. For seed longevity, 2 months burial in the field killed almost all seeds without the pericarp, while more than 70% of the seeds with the pericarp intact remained viable. These results indicated that the pericarp was beneficial for seedling establishment and seed longevity in arid environments. The results of this study may have practical application in grassland restoration in dry areas, especially for aerial seeding, which has been extensively used in the northern part of China.     

Changes in the Strength of Lettuce Endosperm during Germination

The forces required to puncture intact lettuce (Lactuca sativa) seed and pericarp, endosperm and embryo were measured by the Instron Universal Testing Machine. It required about 0.6 newton to puncture the endosperm in seeds imbibed in the dark at 6, 12 and 24 hours. Endosperm of seeds imbibed in the light or in dark with gibberellic acid required about 4.2 newtons at 6 and at 12 hours and only about 0.15 newton at 24 hours. Forces required to puncture embryo at all treatments and times remained constant at about 0.3 newton. Changes in the strength of the endosperm do not appear to be related directly to protrusion of the radicle.     

The promoter of the asi gene directs expression in the maternal tissues of the seed in transgenic barley

The bifunctional alpha-amylase/subtilisin inhibitor (BASI) is an abundant protein in barley seeds, proposed to play multiple and apparently diverse roles in regulation of starch hydrolysis and in seed defence against pathogens. In the Triticeae, the protein has evolved the ability to specifically inhibit the main group of alpha-amylases expressed during germination of barley and encoded by the amyl gene family found only in the Triticeae. The expression of the asi gene that encodes BASI has been reported to be controlled by the hormones abscisic acid (ABA) and gibberellic acid (GA). Despite many studies at the gene and protein level, the function of this gene in the plant remains unclear. In this study, the 5'-flanking region (1033 bp, 1033-asi promoter) and the 3'-flanking region (655 bp) of the asi gene were isolated and characterised. The 1033-asi promoter sequence showed homology to a number of ciselements that play a role in ABA and GA regulated expression of other genes. With a green fluorescent protein gene (gfp) as reporter, the 1033-asi promoter was studied for spatial, temporal and hormonal control of gene expression. The 1033-asi promoter and its deletions direct transient gfp expression in the pericarp and at low levels in mature aleurone cells, and this expression is not regulated by ABA or GA. In transgenic barley plants, the 1033-asi promoter directed tissue-specific expression of the gfp gene in developing grain and germinating grain but not in roots or leaves. In developing grain, expression of gfp was observed specifically in the pericarp, the vascular tissue, the nucellar projection cells and the endosperm transfer cells and the hormones ABA or GA did not regulate this expression. In mature germinating grain gfp expression was observed in the embryo but not in aleurone or starchy endosperm. However, GA induced gfp expression in the aleurone of mature imbibed seeds from which the embryo had been removed. Expression in maternal rather than endosperm tissues of the grain suggests that earlier widespread assumptions that the protein is expressed largely in the endosperm may have been largely based on analysis of mixed grain tissues. This novel pattern of expression suggests that both activities of the protein may be primarily involved in seed defence in the peripheral tissues of the seed.     

A Preliminary Study on Neutral and Acid Inhibitors in the Seed of Kalopanax scptemlobus

The method of extraction, isolation, purification and identification of the neutral and acid inhibitors in the seeds of Kalopanax Septemlobus was given. It is proved that the neutral inhibitor is coumarin, the acid inhibitor is abscisic acid (ABA) by means of paper chromatograph, thin layer chromatograph, high performance liquid chromatograph (HPLC), color reaction and bioassay. The neutral inhibitor can strongly inhibite not only the seed germination of Brassica Chinensis and the radical elongation, but also that of the seed of Kalopanax septemlobus. The study showed that ABA and coumarin exist in the seed coat, endosperm and pericarp of the Kalopanax Septemlobus seed. Both ABA and coumarin can transport from seed cover (pericarp, seed coat)to the interior (endosperm, embryo) as the seeds were stored in refrigerator. In addition, the different results of extracting neutral inhibitor with water, methanol, and alcohol were compared in this paper.     

Applications of NMR micro-imaging to the study of water,lipid, and carbohydrate distribution in grape berries

Summary The technique of nuclear magnetic resonance (NMR) micro-imaging has been applied to the study of water, lipid, and soluble carbohydrate distribution in intact grape berries. Conventional¹H spin echo images reveal details of berry vascular structure, which can be enhanced by suitable choice of imaging parameters. Change in water distribution during drying can also be observed non-invasively. By means of chemical shift imaging methods, it is possible to image separately the distributions of water, lipid, and soluble carbohydrate (glucose and fructose) in selected berries, with an in-plane resolution of 60 m. The technique demonstrated concentration of lipid (oil) in the seeds of intact, mature Shiraz grapes, in a relatively narrow zone in the endosperm, next to its interface with the inner layer of the seed coat, although the lipid zone did not extend entirely around the endosperm perimeter. Carbohydrate, consisting mainly of glucose and fructose in approximately equal proportions, was shown to be evenly distributed in the placental and pericarp tissues of mature grapes. In some cases magnetic field distortions due to the presence of air pockets in seeds of Chardonnay grapes and in seed traces of mature Sultana grapes were also present, leading to an artefactual appearance of localised high sugar in the chemical shift images of these berries.     

刺楸种子中性与酸性抑制物质的研究

本文研究了刺楸种子抑制物质的提取,分离和鉴定方法,并测定了抑制物质的相对活性及其含量。结果表明,刺揪种子中除含高水平的酸性抑制物外,还存在一种中性抑制物。该中性抑制物同酸性抑制物相似,有较强的生物活性,不但可以抑制白菜种子的萌发与胚根生长,而且对已解除休眠的刺楸种子也有显著作用。利用纸层析,薄层层析,颜色反应和高效液相色谱等手段,证明中性抑制物质为香豆素类物质;酸性抑制物质的主要成分为脱落酸。种子各部位均含这两种抑制物质,但含量有所不同,随种子贮藏时间的延长,抑制物会发生转移。本文还讨论了用不同溶剂提取中性抑制物的效果。     

Changes in content of sugars and their exosmose from maize kernels in relation to cold resistance

Changes in soluble sugar content in individual parts (embryo, endosperm and pericarp) of maize caryopses exposed to the influence of 24°, 10° and 6° were studied. At the same time the eluates from sand in which the seeds were planted and exposed for various periods were analysed by paper chromatography. It was found that the lower was the temperature of exposure the greater were the amounts of sucrose, glucose, raffinose and other sugars diffused from the caryopses into the medium before the start of germination. The exosmose course and the changes in sugar content in kernel tissues proved that the hydrolysis of storage polysaccharides is not inhibited by low temperatures but that under such conditions the use of products of hydrolysis for the growth of the embryo is inhibited. It is concluded that not only surface parts of endosperm but also the embryo participates in exosmose. The relatively high sugar exosmose found from seeds germinated at low temperatures explains the well-known interaction of pathogenic and parasitic microorganism in cold resistance during emergence.     

Tocopherol and tocotrienol accumulation during development of caryopses from barley (Hordeum vulgare L.)

Tocotrienols are lipophilic antioxidants belonging to the tocochromanols, better known as vitamin E. Although present in cereal grains in high quantities not much is known about their function in plants. In a detailed study the temporal and spatial accumulation of tocotrienols and tocopherols during grain development in two barley cultivars was analyzed. Tocochromanols and lipids accumulated in parallel until 80% of the final dry weight of the kernels was reached. Later on the tocochromanol content did not change while the lipid content decreased. Generally, only about 13% of the tocochromanols were found in the germ fraction, whereas the pericarp fraction contained about 50% and the endosperm fraction about 37% of the tocochromanols. Altogether, about 85% of the tocochromanols were tocotrienols in both cultivars. In case of the tocopherols about 80% were found in the germ fraction and the remaining 20% in the pericarp fraction. Tocotrienols were almost equally present in the pericarp and the endosperm fraction. Individual forms of tocopherols and tocotrienols accumulated with different kinetics during barley grain development. The differences in distribution and accumulation indicate different functions of the individual tocochromanols during grain development.     

利用原子吸收光谱法和电镜能谱仪法分析重金属Pb、Cd在水稻颖果不同部位中的分配

比较研究了传统原子吸收光谱法与电镜能谱仪法分析重金属Pb、Cd在水稻籽粒不同部位中的分配情况,研究结果表明:两种方法均显示,Pb、Cd在水稻颖果中的分配为胚>糊粉层>果皮>近糊粉层处胚乳>颖果中心,其中,胚、糊粉层和果皮Pb、Cd含量差异较小,整个胚乳Pb、Cd含量变化也不大,但胚、糊粉层和果皮Pb、Cd含量显著高于胚乳.扫描能谱仪能够准确反映重金属在植物不同部位分布的差异,结果与原子吸收光谱法无显著差异.扫描能谱仪法的优点在于操作方便快捷,但是只能用于定性,不能定量测定出某一部位重金属的准确含量,因此,不能代替传统的原子吸收光谱法.     

Some effects of temperature during seed development on carrot (Daucus carota) seed growth and quality

The growth and development of carrot seeds cv. Chantenay Red-cored Royal Chantenay at day/night temperatures of 20/10°C, 25/15°C and 30/20°C and subsequent seed performance were examined in 1984 and 1985. An increase in temperature from 20/10°C to 30/20°C reduced mean weight per seed by 20% in 1984 and by 13% in 1985. There were no effects of temperature on endosperm + embryo weight, or on endosperm cell number but the weight of pericarp decreased with an increase in temperature. Seeds grown at the highest temperature had the largest embryos and the highest nitrogen, DNA and rRNA content; they germinated and emerged earlier, and gave higher percentage seedling emergence than those grown at the lowest temperature. There were no effects of temperature during seed growth on the rate of imbibition of water by seeds during the germination process.     

Cytopathology of Lettuce Mosaic Virus-infected Lettuce Seeds and Seedlings

The ultrastructure of lettuce mosaic potyvirus (LMV)-infected lettuce seeds and seedlings was studied by transmission electron microscopy. Conventional thin-section electron microscopy and immunogold cytochemistry were both successfully employed to study the location of LMV in embryonic and non-embryonic seed parts. LMV particle aggregates and cytoplasmic “pinwheel” inclusions characteristic of potyviruses were observed throughout the embryonic tissues (radicle, hypocotyl and cotyledon) of infected lettuce seeds and seedlings, and also in the non-embryonic endosperm layer. LMV particles, but not inclusions, were also located in the non-embryonic pericarp layer.     

Occurrence and distribution of tomato seed-borne mycoflora in Saudi Arabia and its correlation with the climatic variables

One hundred samples of tomato seeds were collected in 2011 and 2012 from tomato-cultivated fields in Saudi Arabia and screened for their seed-borne mycoflora. A total of 30 genera and 57 species of fungi were recovered from the collected seed samples using agar plate and deep-freezing blotter methods. The two methods differed as regards the frequency of recovered seed-borne fungi. Seven fungi among those recovered from tomato seeds, which are known as plant pathogens, were tested for their pathogenicity and transmission on tomato seedlings. The recovery rate of these pathogens gradually decreased from root up to the upper stem, and did not reach to the stem apex. The distribution of tomato seed-borne fungi was also investigated throughout Saudi Arabia. In this concern, Al-Madena governorate recorded the highest incidence of fungal flora associated with tomato seeds. The impact of meteorological variables on the distribution of tomato seed-borne mycoflora was explored using the ordination technique (canonical correspondence analysis). Among all climatic factors, relative humidity was the most influential variable in this regard. Our findings may provide a valuable contribution to our understanding of future global disease change and may be used also to predict disease occurrence and fungal transfer to new uninfected areas.     

Isolation of Fertilized Embryo Sacs and Zygotes and Triggering of Zygote Division in Vitro in Nicotiana tabacum

Three methods were established to isolate fertilized embryo sacs in Nicotiana tabacum, i. e. enzymatic maceration combined either with shaking, microdissection or grinding respectively. Living fertilized embryo sacs of various developmental stages after fertilization could be isolated successfully by these methods. Each method had its own adoptation to the materials of different developmental stages. Among them the method of enzymatic maceration combined with grinding was the best:Ovules were first treated in enzymatic mixture (1% cellulase R-10, 0.5% macerozyme R-10, 12% mannitol, pH 5.7) for about 30 min. Then droplets of the ovule suspension were gentlely grinded by a flat-headed glass rod. After grinding several droplets of mannitol solution (8%～ 10%) were added for releasing and washing embryo sacs. Compared with the other two methods this method was more convenent and had higher isolation efficiency. Isolation of fertilized embryo sacs offered a good means for microscopic observation on the postfertilization development including synergid degeneration, endosperm formation and zygotic changes without interference by the surrounding sporophytic tissue. Living zygotes and endosperm cells could be further isolated by a second enzymatic maceration procedure followed by brief micromanipulation. Several characters had been found to distinguish the protoplas'ts of free zygotes from those of other cell sources. Isolated zygotes were cultured in microchambers (Millicell-CM) feeded with macrocultured mesophyll protoplasts. The first division of zygotes was induced, resulting in proembryos consisting of two cells.     

Development of a seed DNA-based genotyping system for marker-assisted selection in maize

Leaf collection from the field, labeling and tracking back to the source plants after genotyping are rate limiting steps in leaf DNA-based genotyping. In this study, an optimized genotyping method using endosperm DNA sampled from single maize seeds was developed, which can be used to replace leaf DNA-based genotyping for both genetic studies and breeding applications. A similar approach is likely to be suitable for all plants with relatively large seeds. Part of the endosperm was excised from imbibed maize seeds and DNA extracted in 96-tube plates using individuals from eight F₂ populations and seven inbreds. The quality of the resultant DNA was functionally comparable to DNA extracted from leaf tissue. Extraction from 30 mg of endosperm yields 3–10 μg DNA, which is sufficient for analysis of 200–400 agarose-gel PCR-based markers, with the potential for several million chip-based SNP marker analyses. By comparing endosperm DNA and leaf DNA for individuals from an F₂ population, genotyping errors caused by pericarp contamination and hetero-fertilization were found to average 3.8 and 0.6%, respectively. Endosperm sampling did not affect germination rates under controlled conditions, although under normal field conditions the germination rate, seedling establishment, and growth vigor were significantly lower than that of non-sampled controls for some genotypes. However, careful field management can compensate for these effects. Seed DNA-based genotyping lowered costs by 24.6% compared to leaf DNA-based genotyping due to reduced field plantings and labor costs. A substantial advantage of this approach is that it can be used to select desirable genotypes before planting. As such it provides an opportunity for dramatic improvements in the efficiency and selective gain of breeding systems based on optimum combinations of marker-assisted selection and phenotypic selection within and between generations.     

Kaffeinsynthese in Früchten und Gewebekulturen von Coffea arabica

Summary During fruit development the relative caffeine content of the pericarp falls from 1.68% to 0.24% on a dry weight basis, but remains more or less constant in the seed (about 1.25%). On an absolute basis, the pericarp has twice as much and the seed twenty times as much caffeine at maturity as at the beginning of fruit development. Tissue cultures of seed tissue (endosperm) produce caffeine and release it into the growth medium. Both pericarp and endosperm fed with NaH¹⁴CO₃ synthesize ring-labelled caffeine. Light strongly stimulates the methylation step of caffeine synthesis in the pericarp.

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Diese Arbeit wurde vom Schweizerischen Nationalfonds für wissenschaftliche Forschung unterstützt.     

Fructan contents and dry matter deposition in different tissues of the wheat grain during development

The role of fructan metabolism in the assimilate relations of the grain of wheat (Triticum aestivum L.) was investigated by determination of the dry matter and fructan content of grain components at short intervals during grain filling. During the initial phase of rapid expansion, most of the assimilates entering the grain were partitioned to the outer pericarp. A large fraction of these assimilates were used for the synthesis of fructan. Dry matter deposition and fructan synthesis in the outer pericarp ceased at about 5d after anthesis. At the same time, the endosperm and the inner pericarp and testa started to accumulate dry matter at a fast rate. This was also associated with significant fructan synthesis in the latter tissues. The outer pericarp lost about 45% of its former maximum dry weight between 9 and 19 d after anthesis. This loss was due almost entirely to the near complete disappearance of water-soluble carbohydrates, most of which was fructan. The inner pericarp and testa accumulated dry matter until about mid-grain filling. The fructan contents of the inner pericarp and testa and the endosperm decreased slowly towards the end of grain filling. Most of the fructans in the inner pericarp and testa and the endosperm had a low molecular weight, whereas higher molecular weight fructans predominated in the outer pericarp. The embryo did not contain fructan. The presence of low molecular weight fructans in the endosperm cavity at mid-grain filling was confirmed. It is suggested that fructan synthesis is closely linked to growth-related water deposition in the different tissues of the wheat grain and serves to sequester the surplus of imported sucrose.