Isolation and identification of a plant growth promotive substance from mixture of essential plant oils

The PCS (commercial products by Field Science Co, Japan, used for air fresheners) was analyzed for the presence of bioactive constituents and their role as root growth promoters. Chromatographic separation of the methanolic solution of PCS resulted in the isolation of an promoting active substance, which was identified using GC-mass spectrometry and NMR spectroscopy as 1,2-propanediol (CH₃CH(OH)CH₂OH). Lettuce seedling growth bioassay as test plant revealed that 1,2-propanediol can act as potent root growth promoter; enhancing the growth of lettuce seedling radicle at a concentration 0.01 ppm. The concentration of 1,2-propanediol in PCS mixture was estimated as 4 g/l. These studies suggest that 1,2-propanediol might play an important role in the plant growth promoting activity of PCS.     

The strain energy function in axial plant growth

A model for axial plant growth is formulated based on conservation of energy. The model derivation assumes that a strain energy function exists to describe the dissipation of potential energy associated with water uptake, mechanical deformation, and biosynthesis during growth. The derivation does not, however, make any further assumption on the mathematical form of this constitutive relation. The model is employed to investigate possible forms of the strain energy function as applied to steady root growth. Solutions of the nonlinear partial differential equations governing growth are given for cases when the third derivative of the strain energy function is >, <, or =0. These three cases encompass a multitude of mathematical forms of the strain energy function. The resulting solutions are compared with the realization of steady axial root growth. The results of this analysis indicate that a quadratic form of the strain energy function best described steady growth. This conclusion is consistent with previous assumptions on the form of constitutive relations for growth, and allows further interpretation on the water relations, mechanical, and biosynthetic energies associated with plant growth.Research support provided by state and federal funds appropriated to the OSU/OARDC. Journal article no. 12–88     

川西北高寒草地3种主要植物的生长及物质分配对温度升高的响应

在野外自然条件下采用开顶式生长室模拟增温的方法, 研究了增温对川西北高寒草地3种主要植物(单子叶草本植物垂穗披碱草(Elymus nutans)和双子叶草本植物尼泊尔酸模(Rumex acetosa)和鹅绒委陵菜(Potentilla anserina))的生长及物质分配的影响。研究结果表明, 增温对3种植物的生长产生了显著影响, 垂穗披碱草和尼泊尔酸模的比叶面积和生物量积累在增温后显著增加, 而鹅绒委陵菜在增温后显著减少。在各组分中, 增温处理使尼泊尔酸模的叶生物量显著增加, 根生物量却显著下降, 而鹅绒委陵菜叶和茎的生物量在增温后显著减少, 根生物量却显著增加。增温对尼泊尔酸模各组分的养分含量产生了显著影响, 其中, 根部碳含量在增温后显著增加, 而氮含量在增温后显著减少。增温对尼泊尔酸模和鹅绒委陵菜的生物量在各组分中的分配产生了显著影响, 增温显著增加了尼泊尔酸模的叶重比(LMR)、根重比(RMR)和地下生物量/地上生物量(R/S), 而茎重比(SMR)在增温后却显著降低; 增温显著增加了鹅绒委陵菜的RMR和R/S, 而SMR和LMR在增温后却显著降低。增温对尼泊尔酸模和鹅绒委陵菜各组分中的碳、氮分配产生了显著影响, 增温显著增加了碳、氮在尼泊尔酸模叶片的分配比例, 并且使尼泊尔酸模根部的碳分配比例也显著增加, 而茎部的碳、氮分配比例却显著减少; 增温显著减少了碳在鹅绒委陵菜叶片的分配比例, 而根部的碳、氮分配比例却显著增加。     

Bacteria with ACC deaminase can promote plant growth and help to feed the world

To feed all of the world's people, it is necessary to sustainably increase agricultural productivity. One way to do this is through the increased use of plant growth-promoting bacteria; recently, scientists have developed a more profound understanding of the mechanisms employed by these bacteria to facilitate plant growth. Here, it is argued that the ability of plant growth-promoting bacteria that produce 1-aminocyclopropane-1-carboxylate (ACC) deaminase to lower plant ethylene levels, often a result of various stresses, is a key component in the efficacious functioning of these bacteria. The optimal functioning of these bacteria includes the synergistic interaction between ACC deaminase and both plant and bacterial auxin, indole-3-acetic acid (IAA). These bacteria not only directly promote plant growth, they also protect plants against flooding, drought, salt, flower wilting, metals, organic contaminants, and both bacterial and fungal pathogens. While a considerable amount of both basic and applied work remains to be done before ACC deaminase-producing plant growth-promoting bacteria become a mainstay of plant agriculture, the evidence indicates that with the expected shift from chemicals to soil bacteria, the world is on the verge of a major paradigm shift in plant agriculture.     

Characterization and efficacy of Muscodor cinnamomi in promoting plant growth and controlling Rhizoctonia root rot in tomatoes

Muscodor cinnamomi was selected and investigated for its in vitro ability to produce indole-3-acetic acid (IAA) to solubilize different toxic metal (Ca, Co, Cd, Cu, Pb, Zn)-containing insoluble minerals and tolerance to metals, herbicides and an insecticide. The results indicated that this fungus is able to produce IAA (45.36 ± 2.40 μg ml⁻¹) in liquid media. This phytohormone stimulated coleoptile elongation, and increased seed germination and root elongation of tested plants. The metal tolerance and solubilizing ability depended on the type of insoluble minerals. M. cinnamomi showed the highest growth tolerance on Ca-containing media at 150 mM, followed by Zn-containing media at 100 mM and Cd-containing media at 10 mM. This fungus tolerated the three herbicides (2,4-d-dimethylammonium, glyphosate and paraquat dichloride) and an insecticide (methomyl) at the recommended dosages for field application. Moreover, M. cinnamomi completely controlled Rhizoctonia solani AG-2 root rot in tomato plants, and increased root length, shoot dry weight and root dry weight. This is the first report of in vitro IAA production, solubilization of insoluble metal minerals, and tolerance to herbicides, an insecticide and metals as well as the plant growth promoting ability of M. cinnamomi.     

How do plant growth substances work? II

Abstract. This article continues the discussion on sensitivity prompted by the publication of an earlier paper by the author in 1981. It is indicated that appropriate measurements of sensitivity can help uncover the function of growth substances in development. The experimental constraints which are necessary for unambiguous measurements of sensitivity are outlined and it is shown that a specific sensitivity measurement, termed control strength, would most readily clarify function and help obviate controversy. Methods for measuring control strength which deal with the problem of compartmentalization are considered and it is suggested that stochastic variation in single cell biochemistry might provide a constraint on the accuracy of control strength determinations.     

Gene expression profiling through microarray analysis in Arabidopsis thaliana colonized by Pseudomonas putida MTCC5279, a plant growth promoting rhizobacterium

Plant growth promotion is a multigenic process under the influence of many factors; therefore an understanding of these processes and the functions regulated may have profound implications. Present study reports microarray analysis of Arabidopsis thaliana plants inoculated with Pseudomonas putida MTCC5279 (MTCC5279) which resulted in significant increase in growth traits as compared with non-inoculated control. The gene expression changes, represented by oligonucleotide array (24652 genes) have been studied to gain insight into MTCC5279 assisted plant growth promotion in Arabidopsis thaliana. MTCC5279 induced upregulated Arabidopsis thaliana genes were found to be involved in maintenance of genome integrity (At5g20850), growth hormone (At3g23890 and At4g36110), amino acid synthesis (At5g63890), abcissic acid (ABA) signaling and ethylene suppression (At2g29090, At5g17850), Ca⁺² dependent signaling (At3g57530) and induction of induced systemic resistance (At2g46370, At2g44840). The genes At3g32920 and At2g15890 which are suggested to act early in petal, stamen and embryonic development are among the downregulated genes. We report for the first time MTCC5279 assisted repression of At3g32920, a putative DNA repair protein involved in recombination and DNA strand transfer in a process of rapid meiotic and mitotic division.     

General proof of the validity of a new tensor equation of plant growth

Plant cell/organ growth may be partly described by a local tensor equation. We provide a mathematical proof that the Lockhart (global) equation is the diagonal component of this tensor equation.     

中国进境植物及植物产品携带蚧虫疫情分析

【背景】蚧虫是半翅目胸喙亚目蚧总科下的一类昆虫的总称。蚧虫个体小、食性广,极易随货物扩散传播。【方法】分别从疫情概况、截获种类、产地、截获载体、截获年份等方面对10年来我国各口岸截获蚧虫的信息数据进行了比对和统计,并对之前容易被忽视的非检疫性蚧虫疫情进行了统计和分析。【结果】2005年以来,我国从进口植物和植物产品中截获蚧虫共计171978批次,其中,检疫性蚧虫12种共7071批次;南洋臀纹粉蚧截获量最大,达2848批次,大洋臀纹粉蚧次之,为2442批次,第3是新菠萝灰粉蚧,为1714批次。东南亚是蚧虫的主要来源地,截获量居前3位的蚧类几乎都来自该地区;水果是截获蚧虫的主要载体,占所有植物及植物产品总截获量的99.0%;总体来看,蚧虫截获量从2006年开始逐年下降,到2010年后又呈暴发性上升趋势。比较3种截获量较大的蚧虫发现,2005~2008年,截获主要以南洋臀纹粉蚧为主;自2009年起,大洋臀纹粉蚧截获量逐年上升,成为截获量最多的蚧虫;2011年以来,新菠萝灰粉蚧截获量激增。2005年至今,我国口岸共截获其他非检疫性蚧类68797批次,鉴定到种的有46个属105种共68712批次,其中,在我国内陆地区尚未报道的有23个种,入侵风险高,需要引起重视。【结论与意义】了解我国口岸蚧类害虫截获情况,有利于针对性地开展疫情检疫与监测,有效防范蚧类害虫的传入与扩散。     

Potential of yeasts as biocontrol agents of soil-borne fungal plant pathogens and as plant growth promoters

Among soil microorganisms, yeasts have received little attention as biocontrol agents of soil-borne fungal plant pathogens in comparison to bacterial, actinomycetes, and filamentous fungal antagonists. The mechanisms of action of potential antagonism by yeasts in relation to soil-borne fungal plant pathogens are expected to be similar to those involved with pathogens of aerial parts of the plant, including leaves and fruits. Several taxa of yeasts have been recorded as endophytes in plants, with a small proportion recorded to promote plant growth. The ability of certain taxa of yeasts to multiply rapidly, to produce antibiotics and cell wall-degrading enzymes, to induce resistance of host tissues, and to produce plant growth regulators indicates the potential to exploit them as biocontrol agents and plant growth promoters. More than ten genera of yeasts have been used to control postharvest diseases, especially of fruits. Suppression of classes of fungal pathogens of fruits and foliage that are similar to those associated with soil-borne fungal root pathogens, strongly suggests that yeasts also have potential for the biological control of diseases caused by soil-borne fungal plant pathogens, as is evident in reports of certain yeasts in suppressing some soil-borne fungal plant pathogens. This review explores the potential of soil yeasts to suppress a wider range of soil-borne fungal plant pathogens and to promote plant growth.     

A method for the study of fungal growth inhibition by plant proteins

A bioassay is described for the study of inhibitory activity of plant proteins on fungal growth. Fungal spores were germinated in liquid growth medium and pipetted into wells of a microtitre plate. Fungal growth was followed spectrophotometrically. The bioassay was tested using crude protein extracts from plant tissues known to have high activities of chitinase and beta-1,3-glucanase, and with purified enzymes. Crude protein preparations and combinations of the purified enzymes produced a temporary reduction of growth but no permanent growth inhibition.     

Basic concepts of computer simulation of plant growth

The experimental study of plant growth and architecture requires two consecutive and complementary approaches. The first one is qualitative and botanical. Through this qualitative analysis, it is possible to divide a tree into botanically homogeneous subunits. The second one is quantitative. Modeling of the functioning of meristems based on stochastic processes has been carried out in the Laboratoire de Modelisation of CIRAD (1980 1990) in combination with extensive experimental work on temperate and tropical plants. Calculations involved in the tree simulations from field data are based on the probabilistic Monte Carlo method for the topological part and on analytical geometry for the morphological part. Data, such as length, angles, elasticities, tropism, are necessary for geometric construction of the plant. The growth model, together with the geometric calculations enables a random plant simulation in 3-D according to geometry for the morphological one. Computer graphics methods are then used to visualize the computed plant (perspective, colours, texture, shadows); they require special programs and graphic computers.     

Alleviation of salt stress by plant growth regulators and IAA producing bacteria in wheat

The action of phytohormone producing bacteria and plant growth regulators on germination and seedling growth of wheat under saline conditions were studied. Seed dormancy enforced by salinity (100 mM NaCl) was substantially alleviated and the germination was promoted by gibberellin, auxin, zeatin, and ethephon from 54 to 97%. The IAA producing bacterial strains Pseudomonas aureantiaca TSAU22, Pseudomonas extremorientalis TSAU6 and Pseudomonas extremorientalis TSAU20 significantly increased seedling root growth up to 25% in non-salinated conditions and up to 52% at 100 mM NaCl, compared to control plants. It is concluded that growth regulators considerably alleviated salinity-induced dormancy of wheat seeds. The facts mentioned above make it possible to recommend root colonizing bacteria that produce phytohormone to alleviate salt stress of wheat grown under conditions of soil salinity.     

植物根际促生菌对3种土传真菌病害病原的抑制作用

【目的】获取促生同时可防治3种土传真菌病害(Fusarium oxysporum、Sclerotinia sclerotiorum和Rhizoctonia solani)的生防菌,并明确其抑菌效果。【方法】利用前期研究获得的17株促生菌,采用平板对峙法测定其对病原真菌的拮抗作用及对菌丝生长的抑制作用。【结果】可有效拮抗立枯丝核菌的生防菌有6株,其中促生菌株FX2和LM4-3的抑制率达73.82%;拮抗尖孢镰刀菌的生防菌有7株,其中FX2的抑制率达到66.81%;拮抗油菜菌核病菌的生防菌有4株,其中菌株LHS11的抑制率高达85.71%。菌株LHS11和JM170通过次生代谢物抑制病原真菌。所有的生防菌对病原菌的菌丝生长均有一定的抑制作用。【结论】筛选得到对3种真菌病害病原具有较好生防作用的菌株LHS11和FX2。     

岑溪药用野生稻高效内生固氮菌分离及促生特性

【目的】以广西岑溪市野生稻保护区的药用野生稻为材料,分离纯化内生细菌,筛选固氮酶活性较高和对作物促生效果较好的菌株。【方法】利用乙炔还原法检测固氮酶活性,采用SDS-PAGE全细胞蛋白电泳和IS-PCR指纹图谱技术对分离到的固氮菌进行聚类。利用16S rRNA基因和nifH基因确定其系统发育地位。采用钼锑抗比色法、Salkowski比色法和CAS检测法分别测定菌株溶磷性、生长素的分泌能力和产铁载体能力。通过平板和盆栽试验检测其对水稻的促生作用。【结果】共分离得到35株内生固氮菌,分为6个类群。其中CX24固氮酶活性最高,经鉴定属于Klebsiella variicola,其固氮酶活性为298.64 μmol/(L·h),为参比模式菌株DSM15968的9倍。另外该菌株还具有较高的溶磷性、分泌生长素和产铁载体能力,能够有效地促进水稻的萌发和生长。【结论】菌株CX24属于Klebsiella variicola,是一株高效内生固氮菌,具有很好的生产应用前景。     

Effect of different plant growth regulators on micro-tuber induction and plant regeneration of Pinellia ternate (Thunb) Briet

An efficient micropropagation system for Pinellia ternate (Thunb) Briet, a traditional Chinese medicinal plant, has been developed. Petiole and lamina of P. ternate were used as explants and cultured on Murashige and Skoog (MS) medium containing different concentrations of different plant growth regulators. The results indicated that low concentration of 2,4-dicholorophenoxy acetic acid (2,4-D), indole-3-acetic acid (IAA) and α-naphthalene acetic acid (NAA) were suitable for micro-tuber induction, but callus induction rate increased with increasing concentrations of growth regulators. Tubers induction rates of petiole and leaf were (81.8 %–100 %) and (89.4 %–96.0 %) respectively, when 0.2 mg l⁻¹ 2, 4-dicholorophenoxy acetic acid, indole-3-acetic acid or α-naphthalene acetic acid were present in the medium. Tubers induction rates of petiole and leaf cultured on MS medium supplemented with 0.2–0.5 mg l⁻¹ 6-benzyl amino purine (6-BAP) were (94.1 %–100 %) and (96.0 %–100 %) respectively. When the concentration of 2,4-dicholorophenoxy acetic acid, α-naphthalene acetic acid and 6-benzyl amino purine was increased to 2.0 mg l⁻¹, callus induction rates of petiole and leaf were 100 % and 98.2 %, 91.0 % and 36.0 %, 62.3 % and 70.0 %, respectively. Different concentration of kinetin (KT) and zeatin (ZT) had no significant effect on micro-tuber induction of petiole. Most petioles showed polarity during the cultivation of explants, when supplemented with different concentrations of auxin or cytokinin in the MS medium.     

Latitudinal variation in plant size and relative growth rate in Arabidopsis thaliana

Latitude is an important determinant of local environmental conditions that affect plant growth. Forty ecotypes of Arabidopsis thaliana were selected from a wide range of latitudes (from 16°N to 63°N) to investigate genetic variation in plant size and relative growth rate (RGR) along a latitudinal gradient. Plants were grown in a greenhouse for 31 days, during which period three consecutive harvests were performed. Plants from high latitudes tended to have smaller plant size in terms of seed size, cotyledon width, rosette size, number of rosette leaves, size (leaf area) of the largest leaves, total leaf area, and total dry weight per plant than those from low latitudes. The mean (±SE) RGR across ecotypes was 0.229 (±0.0013) day⁻¹. There was, however, significant ecotypic variation, with RGR being negatively correlated with latitude. The two main components of RGR, leaf area ratio (LAR) and unit leaf rate (ULR), were also correlated with latitude: LAR increased with increasing latitude while ULR decreased with increasing latitude. It was also found that RGR tended to be negatively correlated with LAR, specific leaf area (SLA) and specific root length (SRL) but to be positively correlated with mean area per leaf (MAL) and ULR. The variation in RGR among ecotypes was relatively small compared with that in the other traits. RGR may be a conservative trait, whose variation is constrained by the trade-off between its physiological (i.e. ULR) and morphological (i.e. LAR) components. Received: 2 November 1997 / Accepted: 28 February 1998     

内生真菌发酵提取物和植物生长调节剂对大豆根际细菌多样性的影响

为了研究内生真菌发酵提取物和植物生长调节剂对大豆根际细菌多样性的影响,采用PCR-DGGE技术分析了各处理中不同发育期的大豆根际细菌群落变化。结果发现发酵提取液和植物生长调节剂能增加部分优势菌群的数量,但对根际细菌类群结构影响并不明显;生育周期也是影响根际细菌数量的重要因素。另外割胶测序发现优势菌群主要是Proteobacteria(变形菌门)、Acidobacteria(酸杆菌纲)、Nitrospira(硝化螺旋菌属)、Bradyrhizobium(慢生根瘤菌属)等,这些也都是大豆根际比较常见的细菌类群。     

潜流湿地和表面流湿地的净化效果与植物生长比较

分别以砾石和土壤为填料构建成潜流人工湿地和表面流人工湿地,处以较大水力负荷的污水处理。比较了两种湿地对污水的净化效果,结果表明在较大水力负荷条件下两种湿地的净化效果都较差,但潜流湿地对各种污染物的净化能力都优于表面流湿地;土柱法测量了湿地植物的根系生物量,结果显示湿地植物地上部分长势差异不明显,但潜流湿地的根系生物量显著低于表面流湿地的根系生物量(P<0.05)。结合前期实验结果得出湿地净化效果不仅与湿地植物根系生物量有相关关系,还与其他因素有一定的相关关系。