中亚滨藜盐囊泡形态结构与发育研究

应用石蜡切片技术,通过光学显微镜和扫描电镜研究了中亚滨藜(Atriplex centralasiaticaIljin)盐囊泡的形态结构与发育.结果表明:中亚滨藜的盐囊泡起源于叶原基、茎尖及幼叶处的表皮细胞,细胞质浓厚,它经过平周分裂(不均等分裂)形成泡状细胞和柄细胞,有的柄细胞继续分裂形成2个柄细胞,其结构由1~2个柄细胞和顶端1个膨大的泡状细胞构成,外面包被一层很厚的多层次的角质层.中亚滨藜的耐盐结构———盐囊泡是一种适应性结构,具有进一步研究、应用的价值.     

等渗盐分与水分胁迫对三角叶滨藜和玉米光合作用的影响

以溶液培养的三角叶滨藜(Atriplex triangularis)和玉米(Zeamays)为材料,测定了等渗的盐分和水分胁迫对2种植物光合作用的短期影响。结果表明:等渗的水分和盐分胁迫均会造成三角叶滨藜和玉米净光合速率(Pn)的降低,而且随着胁迫程度的增强,水分胁迫引起Pn下降的幅度要明显高于等渗的盐分胁迫;在较低渗透胁迫强度下,2种胁迫导致光合速率下降的主要原因是气孔限制;但在环境溶液渗透势为-1.0MPa时,水分胁迫对光合作用的影响逐渐转化成非气孔限制,而盐胁迫仍然是气孔限制起主要作用;由此可见,等渗透势的水分胁迫对2种植物光合系统的影响要明显大于盐分胁迫。     

Cadmium accumulation in Atriplex halimus subsp. schweinfurthii and its influence on growth,proline, root hydraulic conductivity and nutrient uptake

Atriplex halimus subsp. schweinfurthii is a newly found cadmium (Cd)-hyperaccumulator, but there have been no detailed studies on its physiological responses when Cd is hyperaccumulated. A. halimus was grown in hydroponic conditions to investigate the effect of cadmium chloride (CdCl₂) on growth, water status, leaf chlorophyll concentration, proline and Cd accumulation. Treatments were prepared by adding 0, 50, 100, 200 and 400 μM CdCl₂ to the nutrient medium. Plant growth was significantly affected at high-Cd treatments. Increased CdCl₂ decreased chlorophyll concentration, transpiration and root hydraulic conductivity (L₀). Hence water flux had only a little effect on the uptake of Cd in A. halimus seedlings. In contrast, proline content increased with increasing CdCl₂ concentration. Plants accumulated substantial amount of Cd in different plant parts (shoot and root). Most of the Cd taken up was retained in roots (606.51 μg g⁻¹DW after 15 d at 400 μM CdCl₂). The addition of Cd in the culture medium affected calcium (Ca) and potassium (K) nutrition in both shoot and root. A. halimus provides a new plant resource for exploring the mechanism of Cd hyperaccumulation and has potential for use in the phytostabilization of Cd-contaminated salt soils.     

Growth and N2 fixation in mixed cropping of Medicago arborea and Atriplex halimus grown on a salt-affected soil using a 15N tracer technique

Abstract

The objective of this study was to evaluate dry matter (DM), nitrogen yield, N₂ fixation (Ndfa) and soil N uptake (Ndfs) in the shrubby medic (Medicago arborea) and saltbush (Atriplex halimus) grown in pots either solely or in a mixture on a salt-affected soil, using ¹⁵N dilution method. The combined DM of both species was considerably higher than that of solely grown shrubs. The inclusion of saltbush in the mixed cropping system decreased Ndfs by shrubby medic and enhanced % Ndfa without affecting amounts of N₂ fixed. It can be concluded that the use of mixed cropping system of shrubby medic and saltbush could be a promising bio-saline agricultural approach to utilize salt affected soils in terms of forage yield and N₂ fixation.     

Description of Meloidoderita salina sp. n. (Nematoda,Sphaeronematidae) from a micro-tidal salt marsh at?Mont-Saint-Michel Bay in France

Meloidoderita salina sp. n. is described and illustrated from the halophytic plant Atriplex portulacoides L. (sea purslane) growing in a micro-tidal salt marsh in the Mont-Saint-Michel Bay in France. This new species is the first member of Meloidoderita Poghossian, 1966 collected from a saline environment, and is characterized by the following features: sedentary mature females having a small swollen body with a clear posterior protuberance; slightly dorsally curved stylet, 19.9 µm long, with posteriorly sloping knobs; neck region irregular in shape and twisted; well developed secretory-excretory (S–E) pore, with markedly sclerotized S-E duct running posteriorly; prominent uterus bordered by a thick hyaline wall and filled with eggs. The adult female transforms into a cystoid. Eggs are deposited in both egg-mass and cystoid. Cystoids of Meloidoderita salina sp. n. display a unique sub-cuticular hexagonal beaded pattern. Male without stylet, pharyngeal region degenerated, S-E duct prominent, deirids small, developed testis 97.5 µm long, spicules 18.4 µm long, cloacal opening ventrally protruded, small phasmids posterior to cloaca opening and situated at 5.9 (3.2–7.7) µm from tail end, and conical tail ending in a rounded terminus marked with one (rarely two) ventrally positioned mucro. Additionally, some young malesof the new species were observed enveloped in the last J2 cuticle. Second-stage juvenile body 470 µm long, with a 16.4 µm long stylet, prominent rounded knobs set off from the shaft, hemizonid anterior and adjacent to S-E pore, small deirids located just above S-E pore level, genital primordium located at 68–77% of body length, phasmids small and located at about 19 µm from tail tip, and tail 38.7 µm long, tapering to finely pointed terminus with a finger-like projection. Phylogenetic analyses based on the nearly full length small subunit ribosomal DNA sequences of Meloidoderita salina sp. n. revealed a close relationship of the new species with Sphaeronema alni Turkina & Chizhov, 1986 and placed these two species sister to the rest of Criconematina.     

Alien plant assemblages near roads in arid and semi-arid South Africa

Herbaceous and woody alien plants visible from a moving vehicle were recorded along 1 km roadside transects at 5 km intervals over a distance of 5869 km in the semi-arid and arid Fynbos, Succulent Karoo, Nama Karoo and Arid Savanna (Kalahari) biomes in South Africa. Each 1 km transect was classified by biome and vegetation type, mean annual rainfall, rainfall seasonality, soil surface type and landuse adjoining the roadside. Although travelling speed affected the range and frequency of plant species observed, the method was repeatable at a speed of 100 km h^?1. Alien plants occurred in 98% of 119 Fynbos, 81% of 204 Succulent Karoo, 72% of 661 Nama Karoo, 47% of 171 Arid Savanna and 100% of seventeen Grassland transects. Alien species richness per site was correlated with mean annual rainfall, but in all regions, sites adjacent to cultivation had significantly more alien species than sites adjoining rangeland. The alien plant assemblage of the arid winter-rainfall Succulent Karoo included species from mesic winter-rainfall lowland Fynbos and the arid Nama Karoo receives unseasonal rainfall. The frequencies of Prosopis spp., Atriplex spp. and Opuntia ficus-indica were not significantly greater near cultivation, and these perennial plants, all of which are dispersed by indigenous and domestic animals, can invade natural rangeland in arid and semi-arid southern Africa.     

盐生植物--中亚滨藜的研究及用途

通过对中亚滨藜的生长情况观察,以及人工栽培试验数据分析,发现中亚滨藜能够改良土壤,幼苗含有较高的叶蛋白,有很高饲用价值,生物产量巨大,果实入药,有很大的开发潜力.     

榆钱菠菜脯氨酸转运蛋白基因的克隆及转基因拟南芥的耐盐性

脯氨酸是自然界中分布最广泛 ,作用最重要的渗透保护剂之一 ,同时又是高等植物中一类重要的碳源和氮源物质。为了解环境胁迫下脯氨酸的转运调节 ,从一个典型的盐生植物榆钱菠菜 (AtriplexhortensisL .)中通过cDNA文库筛选和 5′_RACE的方法获得了一个全长的cDNA (AhProT1) ,其编码蛋白与脯氨酸转运蛋白有 6 0 %～ 6 9%的同源性 ,含有 11个跨膜结构域。聚类分析表明 ,微生物和高等植物的脯氨酸转运蛋白同源程度相对高于哺乳动物。为进一步分析脯氨酸转运蛋白在植物中的功能 ,将AhProT1置于 35S启动子下转入拟南芥 (Arabidopsisthaliana)。通过同位素示踪法发现 ,与对照植物相比 ,转基因植物在根中积累更多的脯氨酸 ;在一系列不同浓度的盐胁迫试验中 ,转基因植株最高可耐受 2 0 0mmol/LNaCl,并可持续生长 ,而对照植株在 15 0mmol/LNaCl下即已死亡。     

Drainage and Elevation as Factors in the Restoration of Salt Marsh in Britain

Intertidal restoration through realignment of flood defenses has become an important component of the U.K. coastal and estuarine management strategy. Although experimentation with recent deliberate breaches is in progress, the long‐term prognosis for salt marsh restoration can be investigated at a number of sites around Essex, southeast England where salt marshes have been reactivated (unmanaged restoration) by storm events over past centuries. These historically reactivated marshes possess higher creek densities than their natural marsh counterparts. Both geomorphology and sedimentology determine the hydrology of natural and restored salt marshes. Elevation relative to the tidal frame is known to be the primary determinant of vegetation colonization and succession. Yet vegetation surveys and geotechnical analysis at a natural marsh, where areas with good drainage exist in close proximity to areas of locally hindered drainage at the same elevation, revealed a significant inverse relationship between water saturation in the root zone and the abundance of Atriplex portulacoides, normally the physiognomic dominant on upper salt marsh in the region. Elsewhere in Essex natural and restored marshes are typified by very high sediment water contents, and this is reflected in low abundance of A. portulacoides. After a century of reestablishment no significant difference could be discerned between the vegetation composition of the storm‐reactivated marshes and their natural marsh counterparts. We conclude that vegetation composition may be restored within a century of dike breaching, but this vegetation does not provide a reliable indicator of ecological functions related to creek structure.