干旱逆境下小麦幼苗细胞叶绿体内钙离子浓度变化的电镜细胞化学研究

采用改进的焦锑酸钙沉淀的细胞化学方法 ,探讨了在干旱逆境条件下叶绿体与Ca2 + 水平变化的关系。结果表明 :在正常水分下生长的小麦幼苗 ,其叶绿体中含有少量Ca2 + ;水分胁迫 2 4、4 8h ,叶绿体膜上密布Ca2 + ;随着胁迫时间的增加 ,叶绿体超微结构受到的伤害越发严重 。

汞对小麦幼苗细胞超微结构的影响

本文以丰抗2号小麦为材料,运用溶液培养法和电镜技术,观察了汞对小麦幼苗细胞超微结构的影响,并从超微水平讨论了汞对小麦生长发育和生理化过程的影响。

低温胁迫下夏威夷椰子幼苗叶肉细胞Ca^(2+)水平及细胞超微结构变化的研究

用焦锑酸钙沉淀的电镜细胞化学方法 ,研究了低温胁迫下夏威夷椰子 (PritchardiagaudichaudiiH .Wendl.)幼苗叶肉细胞内Ca2 + 水平的变化 .研究结果表明 ,未经低温处理的夏威夷椰子幼苗叶肉细胞 ,焦锑酸钙沉淀颗粒大量出现在液泡中 ,而细胞基质及细胞间隙中则看不到焦锑酸钙沉淀 .而夏威夷椰子幼苗经过 2℃ ,48h低温处理后 ,细胞基质和细胞膜、液泡膜上焦锑酸钙沉淀增加 ,而液泡中的焦锑酸钙沉淀减少 ,并且超微结构已初步显示出寒害的特征 ,叶绿体外膜部分破损 ,类囊体片层稀疏且排列不规则 .而夏威夷椰子幼苗经过 2℃ ,96h低温处理后 ,Ca2 +大量分布于液泡和细胞基质中 ,细胞间隙中也可见少量斑块状沉淀 ,大部分细胞结构已经严重破损 ,内部结构分辨不清呈现出了遭受严重冷害的症状 .从而揭示了Ca2 +

Cd Distribution and Subcellular Localization in Leaf and Its Effects on Growth of Soybean(Glycine max) Seedlings

In order to investigate Cd accumulation, subcellular distribution, and local-ization in soybean seedlings leaves, soybean seedlings were cultivated in solution containing different concentrations of Cd. The results showed that most Cd associ-ated with the cellwal s and soluble fractions, and a minor part of Cd presented in mitochondria fractions, nuclear and chloroplast fractions, especial y exposure to high Cd concentrations. Under 20.00 mg/L Cd stress, Cd subcellular distribution fol owed a sequence as： soluble fractions （55.00%）＆gt;cellwal s （30.0%）＆gt;mitochondria fractions （8.21%）＆gt;nuclear and chloroplast fractions （6.79%）. Deposited Cd black particles were observed in cellwal s, chloroplasts, nuclei, and vacuoles through electrical microscope slice. This fact indicated that the cellwal s of soybean leaves were the first protecting organel es from Cd toxicity, and the cellwal s and soluble fractions were the main place for Cd storage. Due to Cd accumulated in the organel es, the intercellular space was enlarged and the subcellular structure was damaged, especial y for the chloroplasts.

Influence of Copper Stress on Ultra-structure of Wheat Seedlings

Transmission Electron Microscope (TEM) Technology was used to investigate the effect of 25,100 and 200 mg/kg copper on ultra-structure of root tip and leaf blade of wheat. Result showed that serious damage was found with Copper of 25,100 and 200 mg/kg. Plasmolysis,concentrated cytoplasm,chloroplast inflation,lamellar structure disturbance,capsule disappearance and disintegration,mitochondria structures ambiguity and vacuolization were all symptoms under Cu stress. There were positive correlation between concentration of coper stress and the degree of injury,and the degree of injury of copper were different in different organelles. Mitochondria were the most sensitive organelles,and there was patient difference in the same organelles of different parts.

Variation in chromosome number in the seedling progeny of a somaclone of Paspalum dilatatum

The somaclone, C39, derived by tissue culture from the obligate apomict Paspalum dilatatum cv Raki (2n=50), had 50 chromosomes and a karyotype apparently identical to Raki.SC2 seedlings of C39 showed a high degree of phenotypic variation which was of ten associated with increased chromosome numbers, but some of the variant seedlings were karyotypically indistinguishable from Raki or C39. Plants with increased chromosome numbers exhibited a high degree of intraplant chromosome variation (aneusomaty). In one of the SC2seedlings, the chromosome number of root tip cells varied from 58 to 82 and in several other seedlings the range was more than 10. The results suggested that the ability to form seed apomictically was much reduced in C39 and that this plant showed some capacity for sexual reproduction and the resulting seedlings, with a chromosome number of about 70, were genetically unstable. Of 11 SC2 seedlings examined cytolog ically, 6 did not produce any viable seed. Seedlings grown from seed of the remaining 5 plants showed that aneusomaty persisted in the SC3 generation. SC3 seedlings which were phenotypically similar to their maternal parent showed a similar range of chromosome numbers to that parent. Some of the SC3 seedlings exhibited an even wider range of chromosome numbers (e.g.56-136), and these plants were all dwarfs.

A Comparative Study of the Cellular Microscopic Characteristics and Mechanisms of Maize Seedling Damage from Superabsorbent Polymers

Superabsorbent polymers(SAPs) as soil moisture conditioners have been increasingly used in agriculture, but conflicting results were reported regarding the effects of SAPs on crop growth. In this study, both laboratory cultivation and analysis were conducted to investigate the effects of different SAPs on the growth and physiology of crops under water-saving agricultural practices. Maize(Zea mays L.) seedlings were cultivated using distilled water or three different SAP hydrogels, sodium polyacrylate(SP), potassium polyacrylate(PP), and sodium polyacrylate embedded with phosphate rock powder(SPP), as growth media. Growth characteristics of the model plant and damage were assessed using scanning electron microscopy(SEM) and transmission electron microscopy(TEM). The results showed that both the SP and PP treatments had pronounced negative effect on the hydrogels of growth of maize seedlings. The SPP treatment appeared to facilitate the stem-leaf growth and had no obvious adverse effect on root growth. All the three hydrogel treatments caused varying degrees of damage to the organizational structure and cellular morphology of the roots, with the SP and PP treatments causing the most severe damage; the membrane system of root cells was damaged by both SP and PP treatments. An excessive accumulation of sodium and reduction of calcium occurred in the roots may be responsible for the observed damage to the cell membrane system, which, in turn, may have promoted the wilting of the cells.