Influence of nicotianamine and iron supply on formation and elongation of adventitious roots in hypocotyl cuttings of the tomato mutant 'chloronerva' (Lycopersicon esculentum)

The influence of nicotianamine (NA) on formation and elongation of adventitious roots in hypocotyls of de-rooted NA-less mutant seedlings of Lycopersicon esculentum Mill, was examined in relation to the iron supply [ferric N-N'-ethylenediaminedi-(2-hydroxyphenylacetate) (FEDDHA), ferric ethylenediaminetetracetate (FeEDTA), ferric N-(2-hydroxyethyl)-ethylenediaminetriacetate (FeHEDTA, Fe-citrate and FeCl₃] in the nutrient solution. The initiation of root primordia in hypocotyl cuttings was independent of NA and occurred with about the same frequency in both, mutant and wild-type. In the mutant the development of primordia to adventitious roots was blocked at all iron sources used, except FeEDTA. Addition of NA (5x 10⁻⁶ to 2 × 10⁻⁵ M ) to the rooting medium resulted in a fast growth of adventitious roots in mutant cuttings with all iron sources tested. Rooting of wild-type cuttings was independent from NA application and iron sources. We suppose that NA is involved in the intracellular transport of iron. Its function is possibly linked with chelation of ferrous iron in the cell.     

Analyses of spatial patterns and population processes of clonal plants

The nonrandom spatial structure of terrestrial plants is formed by ecological interactions and reproduction with a limited dispersal range, and in turn this may strongly affect population dynamics and population genetics. The traditional method of modelling in population ecology is either to neglect spatial pattern (e.g. in transition matrix models) or to do straightforward computer simulation. We review here three analytical mothods to deal with plant populations in a lattice-structured habitat, which propagate both by seeds that scatter over the whole habitat and by vegetative reproduction (producing runners, rhizomes, etc.) to neighboring vacant sites. [1]Dynamics of global and local densities: Dynamical equations of population density considering nearest-neighbor correlation (spatial clumping) are developed as the joint dynamics of global average density and local density (comparable to mean crowding) based onpair approximation. If there is a linear trade-off between seed production and vegetative reproduction, the equilibrium abundance of the population may be maximized by engaging both means of reproduction. This result is accurately predicted by the pair approximation method, but not by mean-field approximation (neglect of spatial structure). [2]Cluster size distributions: Using global and local densities obtained by pair approximation, we predicted cluster size distribution, i.e. the number of clusters of occupied sites of various sizes. [3]Clonal identity probability decreasing with distance: Multi-locus measurement of allozymes or other neutral molecular markers tells us whether or not a given pair of individuals belong to the same clone. From the pattern of clonal identity probability decreasing with the distance between ramets, we can estimate the relative importance of two modes of reproduction: vegetative propagation and sexual seed production.     

浩浩巴组织培养和快速繁殖

浩浩巴顶芽、茎段在ＭＳ基本培养基中培养,附加植物激素１～２ｍｇ／Ｌ的ＢＡ或ＺＴ和０．２ｍｇ／Ｌ的ＮＡＡ配合使用明显促进芽苗形成。诱导生根采用两步生根法能有效地提高生根率。试管苗移栽获得成活。     

非线性映射和聚类分析在中风病证候分类中的应用

本文用非线性映射和聚类分析方法,给出了中风病的四个类型,为中风病的证候分类提供了分析方法和信息．     

光谱技术研究固氮酶铁硫簇的理化特性

Ｎ－甲基甲酰胺碱度是提取高质量固氮酶铁钼辅基的关键因素之一。过量的亚甲蓝能氧化并分解铁铜铺基为含双相铁硫簇和铁硫簇固氮酶铁钼辅基和在紫外可见光谱区中均无特征吸收峰,而在３２０ｎｍ处却呈弱吸收峰,棕色固氮菌固氮酶和该菌的突变菌侏ＵＷ４５固氮酶（缺铁钼辅基）中的非含钼的铁硫簇在紫外可见光谱区３２０ｎｍ和４０５ｎｍ处均含有特征吸收峰．     

A 19-kb CpG Island Associated with Single-minded Gene 2 in Down Syndrome Chromosomal Region

To help in isolating the genes involved in Down syndrome, wesought CpG islands in 4 Mb cosmid/PAC contigs spanning mostof the 21q.22.2 band using seven rare cutting enzymes. A strikingfeature was observed upstream of hSIM2 where at least 41 rare-cuttingsites were clustered within a 20-kb region. To investigate thestructure of the cluster, a cosmid containing hSIM2 was submittedto shotgun sequencing. Sequence analysis revealed that the clusterwas a long CpG island extending 19, 128 nucleotides which includesin the first and second exons of hSIM2. Taken together withour observation in which the CpG islands were concentrated within1.2 Mb around hSIM2, we propose that this region functions asan R-band, and the cluster provides a unique element for markingof DNA for the spatial and temporal expression of the hSIM2locus.     

Response of understorey vegetation and Scots pine root systems to fertilization at multiple deficiency stress

The stump and root systems of Scots pine (Pinus sylvestris L.) and field-layer vegetation were sampled before and three growing seasons after drainage and fertilization of a low-shrub pine bog in SE Norway. Although the understorey vegetation roots responded significantly to nutrient application with higher concentrations of Ca and P, root biomass weights did not change. The fine and small pine roots responded with higher N, Ca, P and S concentrations, while those of Mn and Zn were significantly reduced. The NPK-application resulted in significantly higher pine root biomass. Relative to the total stores in the root zone the amounts of most elements in roots shifted to higher ratios at NPK-application. High figures for K, B and Mn indicate tight biochemical cycles of these elements. Compared to totals in above and below ground biomass, major parts of Fe and Pb were held by the roots. In contrast the field layer roots kept a very small per cent of total K, while the pine roots were low in Mn. The understorey vegetation was primarily restricted by P-deficiency, while the pine trees were also restricted by low supply of N. The field and the tree layer species seem to differ with respect to required nutrient concentrations in the root zone. These characteristics are important for direction and extent of successional changes after fertilization in low-shrub pine bog ecosystems.     

Uptake of 24Mg by excised pine roots: A preliminary study

Uptake of ²⁴Mg by excised roots of Pinus sylvestris L. during up to 4 h long incubations in 99.9 atom % ²⁴Mg (50 M) was measured by ICP-MS. A rapid initial uptake phase (30 min) was followed by a slower uptake. This was interpreted as a shift from a phase dominated by saturable ion exchange (free space uptake), to a non-saturable phase, during which the rate of uptake was 0.077±0.0.012 mol Mg g^–1 (d.wt.) h^–1. The metabolic uncoupler DNP (2,4-dinitrophenol) at 50 M decreased the Mg uptake rate by 35% only, but the effect of DNP was significant (p<0.01). Several problems related to a high variability in the experimental material were encountered, and further refinement of this approach in studies of plant Mg uptake is suggested.     

Rhizodeposition under ambient and elevated CO2 levels

As global CO₂ levels rise, can soils store more carbon and so buffer atmospheric CO₂ levels? Answering this question requires a knowledge of the rates of C inputs to soil and of CO₂ outputs via decomposition. Below-ground inputs from roots are a major component of the C flow into soils but are still poorly understood. In this article, new techniques for measuring rhizodeposition are reviewed and discussed and the need for cross-comparisons between methods is identified. One component of rhizodeposition, root exudation, is examined in more detail and evidence is presented which suggests that current estimates of exudate flow into soils are incorrect. A mechanistic mathematical model is used to explore how exudate flows might change under elevated CO₂.