Cadaverine: A lysine catabolite involved in plant growth and development

The cadaverine (Cad) a diamine, imino compound produced as a lysine catabolite is also implicated in growth and development of plants depending on environmental condition. This lysine catabolism is catalyzed by lysine decarboxylase, which is developmentally regulated. However, the limited role of Cad in plants is reported, this review is tempted to focus the metabolism and its regulation, transport and responses, interaction and cross talks in higher plants. The Cad varied presence in plant parts/products suggests it as a potential candidate for taxonomic marker as well as for commercial exploitation along with growth and development.     

The role of serotonin and melatonin in plant morphogenesis: Regulation of auxin-induced root organogenesis in in vitro-cultured explants of st. John's Wort (Hypericum perforatum L.)

Summary St. John's wort (Hypericum perforatum cv. Anthos) is a medicinal plant with historical and anecdotal evidence of efficacy as an anti-depressant. Recent research has demonstrated an active biosynthetic pathway leading to the production of the mammalian neurohormone melatonin in St. John's wort plantlets. The objective of the current study was to assess the physiological role of melatonin and related indoleamines in plant morphogenesis. In the initial experiments, two of the indoleamines; serotonin and melatonin, were supplemented to the culture medium. In subsequent research, six inhibitors of auxin and indoleamine action or transport, 2,3,5-triiodobenzoic acid, p-chlorophenoxyisobutyric acid, p-chlorophenyl-alanine, d-amphetamine, fluoxetine (Prozac^TM), and methylphenidate (Ritalin^TM), were included in a culture medium in the presence or absence of the auxin, indoleacetic acid (IAA). The rate of de novo root and shoot organogenesis and the endogenous concentrations of auxin and indoleamines were determined in cultured explants. Significant reductions in de novo root regeneration were found to correspond with decreases in the pool of both IAA and melatonin. An increase in the endogenous concentration of melatonin was correlated with an increase in de novo root formation, and increased serotonin levels corresponded to increased shoot formation on the explants. Our findings provide the first evidence that a balance of the endogenous concentration of serotonin and melatonin may modulate plant morphogenesis in vitro.     

Effect of plant growth regulators on in vitro fiber development from unfertilized and fertilized Egyptian cotton ovules

Unfertilized and fertilized ovules of Gossypium barbadense Giza 45 (extra long staple variety) were used to study the effect of plant growth substances (auxins, gibberellins and cytokinins) on in vitro fiber initiation and development. Kinetin, alone did not increase total fiber unit (TFU) of unfertilized ovules, while an increase in TFU value occurred when a constant level of IAA and GA₃ were used either separately or in combination in the liquid medium. GA₃ used alone, produced a higher TFU value than that produced by IAA, whilst, IAA with a constant level of GA₃ (5 M) produced the highest value of TFU. GA₃ with a constant level of IAA (5 M) produced a lower TFU value. Kinetin reduced the stimulatory effect of IAA and GA₃ on TFU value when used in combination with either substance. In fertilized ovules, the highest level of TFU was reached when IAA, with a constant level of GA₃, was added to the medium, whilst its lowest level was obtained when IAA was used alone. Estimation of in vitro fiber production, as well as the effect of growth substances used in different concentrations on in vitro fiber initiation and development from unfertilized and fertilized ovules of Egyptian cotton varieties Gossypium barbadense Giza 45 are discussed.     

植物生长调节物质IP－1号对木薯产量及其生物性状的影响

１９９０和１９９１年在木薯（ＭａｎｉｈｏｔｅｓｃｕｌｅｎｔａＣｒａｎｔｚ）生长期以植物生长调节物质ＩＰ－１号０,２０,３０和４０ｐｐｍ进行叶面喷洒,结果表明：３０ｐｐｍ处理可使木薯块根产量平均增加５４．４４％,块根淀粉含量平均提高２０．８１％。单株最大薯重提高３１．５５％,块根数增加２１．１７％,块根长度增长１７．６２％,地上部鲜重增加３４．３６％,植株高度增加４．３６％,植株收获期保留青叶数增加１９．４２％,主茎直径增加６．２６％,块根直径增加２．５８％,叶片的叶绿素和蛋白质含量分别提高５．５７％和２５．９６％,叶片光合作用强度提高１５．８６％,而对主茎高度、主茎节数没有明显影响。     

The interface between the cell cycle and plant growth regulators: a mini review

The aim was to review knowledge about the interface betweenplant growth regulators and molecular checkpoints of the cell cycle. Atwhat level of biochemical regulation of the cell cycle do plant growthregulators interface? Are there different levels of interfacingdependent on the plant growth regulator involved? As a preamble totackling these questions, we overview the eukaryotic cell cycle withparticular emphasis on checkpoints that regulate the transition fromG0-G1-S-phase and G2-M. Cytokinins feature strongly as activators ofcell division in plants both in vivo and in vitro.Recent research has shown that zeatin treatment led to the up-regulationof CycD3 in Arabidopsis. This is a D-type cyclin showing stronghomology with vertebrate D cyclins which themselves are up-regulated byextracellular growth factors. Benzyladenine treatment can also shortenthe duration of S-phase through recruitment of latent origins of DNAreplication. Kinetin is involved in the phosphoregulation of the G2-Mcheckpoint; the major cyclin-dependent kinase (Cdk) at this checkpointhas recently been shown to be dephosphorylated as a result of cytokinintreatment, an effect which can also be mimicked by the fission yeastCdc25 phosphatase. Hence, a picture emerges of a cytokinin-inducedcontinuum of cell cycle activation through the up-regulation of a plantD-type cyclin at the G1 checkpoint and the phosphoregulation of the Cdkat the G2/M checkpoint. During S-phase, we argue for a link betweencytokinins and the proteins associated with replication origins.Gibberellic acid (GA) treatment induces internode elongation. Indeepwater rice, this response is mediated, at least partly, by aGA-induced up-regulation of a cyclin-Cdk at the G2-M checkpoint. Recentevidence has also linked abscisic acid to a cyclin-dependent kinaseinhibitor. These, so-called CKIs are negative regulators of Cdks whichfits with ABA's general role in growth inhibition; we await news ofethylene interactions. We highlight two instances of plant growthregulator-cell cycle interfacing during development, arguing for aninvolvement in microtubule orientation as a prerequisite to leafinitiation, and suggest a link between IAA and the activation of celldivisions in the pericycle required for lateral root initiation. A newD-type cyclin, recently discovered in Arabidopsis, may have akey role in this process. Finally, a model is presented which features ageneralised cyclin-Cdk checkpoint exhibiting various interfaces with theplant growth regulators.     

Ozone affects gas exchange, growth and reproductive development in Brassica campestris (Wisconsin fast plants)

Exposure to ozone (O(3)) may affect vegetative and reproductive development, although the consequences for yield depend on the effectiveness of the compensatory processes induced. This study examined the impact on reproductive development of exposing Brassica campestris (Wisconsin Fast Plants) to ozone during vegetative growth. Plants were exposed to 70 ppb ozone for 2 d during late vegetative growth or 10 d spanning most of the vegetative phase. Effects on gas exchange, vegetative growth, reproductive development and seed yield were determined. Impacts on gas exchange and foliar injury were related to pre-exposure stomatal conductance. Exposure for 2 d had no effect on growth or reproductive characteristics, whereas 10-d exposure reduced vegetative growth and reproductive site number on the terminal raceme. Mature seed number and weight per pod and per plant were unaffected because seed abortion was reduced. The observation that mature seed yield per plant was unaffected by exposure during the vegetative phase, despite adverse effects on physiological, vegetative and reproductive processes, shows that indeterminate species such as B. campestris possess sufficient compensatory flexibility to avoid reductions in seed production.     

紫外线阻断膜防控茄子害虫效果及对植株生长和果实品质的影响

【目的】紫外线阻断膜可以吸收光线中波长在380 nm以下的紫外光,从而影响昆虫的视觉反应,因此有望用于害虫防控。本研究旨在明确该项措施的可行性。【方法】以日光温室茄子Solanum melongena为作物对象,对紫外线阻断棚和使用普通棚膜的对照棚中3种主要害虫(西花蓟马Frankliniella occidentalis、烟粉虱Bemisia tabaci和桃蚜Myzus persicae)的发生情况进行了比较,分析了紫外线缺失对茄子植株生长和果实品质的影响。【结果】紫外线阻断棚中西花蓟马、烟粉虱和桃蚜的最大发生量均显著低于对照棚(P0.05),分别是对照棚中的44.3%,50.4%和37.5%;与对照棚相比,紫外线阻断棚中茄子株高偏高,但二者差异不显著(P0.05);紫外线阻断棚中茄子产量、果实重量和周长均降低,茄子果实颜色偏浅,果实中维生素C、可溶性糖、可滴定酸、粗脂肪和花青素含量下降(P0.05),Ca,K,Cu和Zn等矿物离子含量上升(P0.05)。【结论】本研究表明紫外线阻断技术可以显著抑制温室茄子上3种主要害虫的种群增长,但对茄子的生长和果实品质有一定影响。今后需要进一步研究该项技术在茄子品种和其他作物中的应用方式。     

Dual function of Arabidopsis glucan synthase-like genes GSL8 and GSL10 in male gametophyte development and plant growth

Members of the glucan synthase-like (GSL) family are believed to be involved in synthesis of the cell-wall component callose in specialized locations throughout the plant. We identified two members of the Arabidopsis GSL gene family, GSL8 and GSL10 , that are independently required for male gametophyte development and plant growth. Analysis of gsl8 and gsl10 mutant pollen during development revealed specific malfunctions associated with asymmetric microspore division. GSL8 and GSL10 are not essential for normal microspore growth and polarity, but play a role in entry of microspores into mitosis. Impaired function of GSL10 also leads to perturbation of microspore division symmetry, irregular callose deposition and failure of generative-cell engulfment by the cytoplasm of the vegetative cell. Silencing of GSL8 or GSL10 in transgenic lines expressing gene-specific dsRNAi constructs resulted in a dwarfed growth habit, thereby revealing additional and independent wild-type gene functions for normal plant growth.     

The role of phytochelates in plant growth and productivity

Plants require minimal amounts of certain metals (Zn,Fe,Cu,etc) for optimal growth and productivity, but excess of these metals leads to cell death. When growth is limited by metal excess or metal deficiency plants respond by synthesizing nonproteinogenic chelating substances. Phytosiderophores are secreted by roots of iron deficient grasses and are important in providing sufficient Fe for normal growth. In response to growth-inhibitory levels of heavy metals plants synthesize metal-binding phytochelatins which detoxify excess metals. Biostimulants such as humic substances and oligomers of lactic acid have properties in common with both phytosiderophores and phytochelatins. The word phytochelates is proposed as a generic term to cover substances that affect plant growth by acting as chelating agents.     

Avian growth and development rates and age-specific mortality: the roles of nest predation and adult mortality

Previous studies have shown that avian growth and development covary with juvenile mortality. Juveniles of birds under strong nest predation pressure grow rapidly, have short incubation and nestling periods, and leave the nest at low body mass. Life-history theory predicts that parental investment increases with adult mortality rate. Thus, developmental traits that depend on the parental effort exerted (pre- and postnatal growth rate) should scale positively with adult mortality, in contrast to those that do not have a direct relationship with parental investment (timing of developmental events, e.g. nest leaving). I tested this prediction on a sample of 84 North American songbirds. Nestling growth rate scaled positively and incubation period duration negatively with annual adult mortality rates even when controlled for nest predation and other covariates, including phylogeny. On the contrary, neither the duration of the nestling period nor body mass at fledging showed any relationship. Proximate mechanisms generating the relationship of pre- and postnatal growth rates to adult mortality may include increased feeding, nest attentiveness during incubation and/or allocation of hormones, and deserve further attention.     

The effect of an experimental growth retardant (WL83801) on leaf growth and development in Lolium perenne L.

The experimental growth retardant WL83801, applied as a root drench, had a rapid and persistent effect in retarding the growth and development of leaves in L. perenne. Leaves of the main shoot were greatly reduced in length, were broader, and appeared faster than in control plants. The rate of extension of individual leaves was greatly reduced in retarded plants but still followed a diurnal pattern that closely corresponded with temperature. There was evidence that leaf extension was far less responsive to temperature in treated plants. At the cellular level WL83801 had no significant effect on leaf blade cell number, thus reductions in leaf length were associated with the retardation of cell elongation. Changes in leaf structure were also observed. These changes in the pattern of leaf growth and development are discussed in relation to the primary mode of action of the growth retardant in interfering with gibberellin biosynthesis.     

甘肃省动植物资源现状及可持续发展对策

甘肃地处中国的中部偏北，位于黄土高原、内蒙古高原和 藏高原的交汇处，是我另唯一横跨三大自然区的 分。全省的动植物资源极春丰富。据不完全调查，共有脊椎动物９２４种和亚种，占国内４８６５种１９．０１％，种子植物３８６７种，占国内３００００种的１２．９％。由于生态环境破坏，乱捕滥猎，使动植物相断消失，许多国家级保护的动植物成为濒危物种。为保护生态环境，实现可持续发展，本文提出了５项持续利用的对策：１）加     

The role of hexokinase in plant sugar signal transduction and growth and development

Previous studies have revealed a central role of Arabidopsis thaliana hexokinases (AtHXK1 and AtHXK2) in the glucose repression of photosynthetic genes and early seedling development. However, it remains unclear whether HXK can modulate the expression of diverse sugar-regulated genes. On the basis of the results of analyses of gene expression in HXK transgenic plants, we suggest that three distinct glucose signal transduction pathways exist in plants. The first is an AtHXK1-dependent pathway in which gene expression is correlated with the AtHXK1-mediated signaling function. The second is a glycolysis-dependent pathway that is influenced by the catalytic activity of both AtHXK1 and the heterologous yeast Hxk2. The last is an AtHXK1-independent pathway in which gene expression is independent of AtHXK1. Further investigation of HXK transgenic Arabidopsis discloses a role of HXK in glucose-dependent growth and senescence. In the absence of exogenous glucose, plant growth is limited to the seedling stage with restricted true leaf development even after a 3-week culture on MS medium. In the presence of glucose, however, over-expressing Arabidopsis or yeast HXK in plants results in the repression of growth and true leaf development, and early senescence, while under-expressing AtHXK1 delays the senescence process. These studies reveal multiple glucose signal transduction pathways that control diverse genes and processes that are intimately linked to developmental stages and environmental conditions.     

Terminally differentiating epithelial tissues in primary explant culture: A model of growth and development

Summary Many epithelial tissues are characterized by the presence of basal cells which serve the dual roles of self-renewal and of progression through terminal differentiation, to a functional state. Such tissues, when grownin vitro as primary explants, exhibit a characteristic pattern of outgrowth and development which includes both renewal and efforts toward normal differentiation. The degree of differentiation achieved depends upon conditions of culture and may be modulated in a variety of ways. The human prostate constitutes such a system and offers numerous possibilities for investigating basic control mechanisms in growth and development. Information on a variety of epithelial tissues is reviewed and experimental results using human prostate tissue are presented. The work was supported by grant R26 CA 2365, National Cancer Institute.     

Importance of plant integrity in crop research,breeding, and production

Plant integrity looks like a “very easy and expanded topic,” but the reality is totally different. Thanks to the very high specialization of scientists, we are losing a holistic view of plants and are making mistakes in our research due to this drawback. It is necessary to sense a plant in their whole complexity—in both roots and shoot, as well as throughout their life cycles. Only such an integrated approach can allow us to reach correct interpretations of our experimental results.     

我国和世蓝浆果的发展前景

蓝浆果是具独特保健作用、生食加工皆宜的适于我国红黄壤地区开发的新兴经济作物。通过对美国一些研究机构和苗圃的考察及参加在智利举行的第七届国际蓝浆果研讨会,对目前世界蓝浆果的发展状况、趋势及一些最新研究成果作了概述,对我国发展蓝浆果的前景、方向等进行了讨论。