Enhancement of growth and yield of tomato by <Emphasis Type="Italic">Rhodopseudomonas</Emphasis> sp. under greenhouse conditions

A greenhouse test was carried out to examine the effects on tomato growth of application of purple non-sulfur bacterium Rhodopseudomonas sp. which had enhanced germination and growth of tomato seed under axenic conditions. The shoot length of tomato plant inoculated by Rhodopseudomonas sp. KL9 increased by 34.6% compared to that of control in 8 weeks of cultivation. During the same period, this strain increased 120.6 and 78.6% of dry weight of shoot and root of tomato plants, respectively. The formation ratio of tomato fruit from flower was also raised by inoculation of KL9. In addition, Rhodopseudomonas sp. KL9 treatment enhanced the fresh weight and lycopene content in the harvested tomato fruits by 98.3 and 48.3%, respectively compared to those of the uninoculated control. When the effect on the indigenous bacterial community and fate of the inoculated Rhodopseudomonas sp. KL9 were monitored by denaturing gradient gel electrophoresis analysis, its application did not affect the native bacterial community in tomato rhizosphere soil, but should be repeated to maintain its population size. This bacterial capability may be applied as an environment-friendly biofertilizer to cultivation of high quality tomato and other crops including lycopene-containing vegetables and fruits.     

Growth,yield and reproduction of dwarf tomato grown under simulated microgravity conditions

Abstract

A closed hydroponic system combined with a horizontal uniaxial clinostat has been used to grow tomato plants (Solanum lycopersicum L.) under simulated microgravity conditions. The study was carried out to evaluate the quanti-qualitative traits (growth, yield and quality) of the dwarf tomato variety ‘Micro-Tom’ grown under simulated microgravity conditions and to determine if tomato plants would complete their life cycle (‘seed-to-seed’). Morphological and growth characteristics of ‘Micro-Tom’ were modified during clinorotation treatment. The ‘Micro-Tom’ plants grown under simulated microgravity exhibited a spreading growth and an increasing of the internode length. Total fruit yield, small fruit yield, leaf area, leaf dry weight, fruit dry weight, total dry weight and shoot – root ratio were lower in the clinorotated tomato plants than those grown in the control treatment. Foliar amount of carotenoids, and chlorophyll a and b were also substantially reduced under simulated microgravity conditions. Quality parameters (total soluble solids and fruit dry matter) of tomato plants were also negatively affected by clinorotation. The number of flowers per plant was increased by 32% in clinorotated plants versus controls. Fruit setting was reduced by 46% under clinorotation, while no significant difference was recorded for the pollen fertility and the seed number in small and large fruits. Clinorotation-exposed and control seeds were used in a germination trial in order to evaluate whether the seeds so formed were viable and if subsequent generations might be obtained in microgravity. Seeds formed under simulated microgravity proved to be biologically and functionally complete (germination = 78.6%) showing that ‘Micro-Tom’ plants could realize complete ontogenesis, from seed to seed in microgravity.     

Impact of two fluorescent pseudomonads and an arbuscular mycorrhizal fungus on tomato plant growth,root architecture and P acquisition

The ability of fluorescent pseudomonads and arbuscular mycorrhizal fungi (AMF) to promote plant growth is well documented but knowledge of the impact of pseudomonad-mycorrhiza mixed inocula on root architecture is scanty. In the present work, growth and root architecture of tomato plants (Lycopersicon esculentum Mill. cv. Guadalete), inoculated or not with Pseudomonas fluorescens 92rk and P190r and/or the AMF Glomus mosseae BEG12, were evaluated by measuring shoot and root fresh weight and by analysing morphometric parameters of the root system. The influence of the microorganisms on phosphorus (P) acquisition was assayed as total P accumulated in leaves of plants inoculated or not with the three microorganisms. The two bacterial strains and the AMF, alone or in combination, promoted plant growth. P. fluorescens 92rk and G. mosseae BEG12 when co-inoculated had a synergistic effect on root fresh weight. Moreover, co-inoculation of the three microorganisms synergistically increased plant growth compared with singly inoculated plants. Both the fluorescent pseudomonads and the myco-symbiont, depending on the inoculum combination, strongly affected root architecture. P. fluorescens 92rk increased mycorrhizal colonization, suggesting that this strain is a mycorrhization helper bacterium. Finally, the bacterial strains and the AMF, alone or in combination, improved plant mineral nutrition by increasing leaf P content. These results support the potential use of fluorescent pseudomonads and AMF as mixed inoculants for tomato and suggest that improved tomato growth could be related to the increase in P acquisition.     

Influence of cadmium on penetration of the root-knot nematode,Meloidogyne incognita and plant growth parameters of tomato

The results of experiment clearly reveal that cadmium inhibited root penetration by the second stage juveniles (J₂) of Meloidogyne incognita which subsequently affected the development of root galls in tomato. The heavy metal was highly injurious to tomato plants at all the concentrations tested for (7.5, 15.0, 30.0 and 60.0?ppm). The inhibitory effect on plant growth and other parameters (fresh and dry weight of plant, chlorophyll content of leaves, water absorption capability of roots) significantly increased with an increase in the concentration of the metal. It was further increased in the presence of the nematode.     

Use of the maize transposonsActivator andDissociation to show that phosphinothricin and spectinomycin resistance genes act non-cell-autonomously in tobacco and tomato seedlings

Cell-autonomous genes have been used to monitor the excision of both endogenous transposons in maize andAntirrhinum, and transposons introduced into transgenic plants. In tobacco andArabidopsis, the streptomycin phosphotransferase (SPT) gene reveals somatic excision of the maize transposonActivator (Ac) as green sectors on a white background in cotyledons of seedlings germinated in the presence of streptomycin. Cotyledons of tomato seedlings germinated on streptomycin-containing medium do not bleach, suggesting that a different assay for transposon excision in tomato is desirable. We have tested the use of the spectinomycin resistance (SPEC) gene (aadA) and a Basta resistance (BAR) gene (phosphinothricin acetyltransferase, or PAT) for monitoring somatic excision ofAc in tobacco and tomato. Both genetic and molecular studies demonstrate that genotypically variegated individuals that carry clones of cells from whichAc orDs have excised from either SPEC or BAR genes, can be phenotypically completely resistant to the corresponding antibiotic. This demonstrates that these genes act non-cell-autonomously, in contrast to the SPT gene in tobacco. Possible reasons for this difference are discussed.     

Increased growth response of plants induced by rhizobacteria antagonistic to soilborne pathogenic fungi

Summary Rhizobacteria applied into pathogen-free soil or peat vermiculite medium, were established in the rhizosphere of plants in population densities of up to 1.9×10⁹ cfu/g. Pseudomonads induced up to 78% bigger roots in tomatoes rooted in water. Pythium-suppressive bacteria increased dry weight of either roots or shoots of tomato, pepper, melon or bean. Fusarium-suppressive bacteria increased emergence of tobacco, cucmber or radish by 10–31% and dry weight by up to 165%. Isolates of the tested bacteria varied in their ability to induce increased emergence and growth of the treated crops.     

Kinetin regulation of growth and secondary metabolism in waterlogging and salinity treated Vigna sinensis and Zea mays

Waterlogging mostly increased fresh weight and water content in shoots and roots of Vigna sinensis and Zea mays while salinity seemed to have a decreasing effect. There was a marked induction of proline in shoots and roots of both plants by salinity with lower values in logged plants. In addition, anthocyanin content was increased in Vigna sinensis by both treatments and in Zea mays only by salinity. Meanwhile the treatments significantly accumulated phenolic compounds in plant shoots. Also there were increased activities of phenylalanine ammonia lyase (PAL) and tyrosine ammonia lyase (TAL) in shoots and roots of both plants. Foliar application of kinetin equilibrated, if any, the effects of both treatments on contents of proline, anthocyanin and phenolic compounds as well as activities of PAL and TAL in shoots and roots of treated plants. These findings reveal that kinetin alleviates the stress symptoms and regulates the changes in phenolic metabolism of waterlogged or salinity treated Vigna sinensis and Zea mays.     

Prevention of flower formation in dicotyledons

Prevention of flower formation is important, for example for preventing the spread of transgenes from genetically modified plants or the spread of non-native species, for increasing vegetative growth or preventing the formation of allergenic pollen. The aim of this study was to determine whether flowering of dicotyledonous plants can be prevented by genetic manipulation without harmful effects on vegetative growth. Here we describe isolation of the BpMADS1 gene (similar to SEP3, formerly AGL9) from birch and show that it is expressed only in the inflorescences. In tobacco and Arabidopsis, the expression of BpMADS1::GUS was also virtually inflorescence-specific. Transgenic tobacco and Arabidopsis containing a BpMADS1::BARNASE construct grew well. In one tobacco line the formation of the inflorescence was completely prevented; in several other lines the flowers lacked stamens and carpels and therefore were sterile. The final dry weights of the shoots of the sterile tobacco lines were 140–200% of those of controls. In Arabidopsis, some of the transgenic lines containing the BpMADS1::BARNASE construct formed inflorescences. Some of these lines formed never flowers and some others formed occasionally single fertile flowers. Some other lines did not form inflorescences, but formed up to about one hundred leaves, even in long-day conditions. These results suggest that formation of flowers or inflorescences in widely different dicotyledonous plants could be prevented using the BpMADS1::BARNASE construct and that prevention of flowering may lead to increased vegetative mass.     

Screening rhizobacteria for biological control of Ralstonia solanacearum in Ethiopia

Bacterial wilt caused by Ralstonia solanacearum (Smith) has become a severe problem mainly on potato and tomato in Ethiopia and no effective control measure is available yet. To explore possibilities for the development of biological control for the disease, 118 rhizobacteria, most of them collected from Ethiopia, were screened against an Ethiopian R. solanacearum strain. On the basis of in vitro screening, six strains (RP87, B2G, APF1, APF2, APF3, and APF4) with good inhibitory effect were selected for in planta testing in a greenhouse. In the greenhouse, soil and tomato seedlings were treated with the antagonists and their effects studied. The study showed that APF1 and B2G strains significantly reduced disease incidence and increased weight of tomato plants. Area under disease progress curves (AUDPC) was reduced by 60% and 56% in plants inoculated with APF1 and B2G strains, respectively. Plant dry weight increase in plants inoculated with APF1 and B2G strains was 96% and 75%, respectively. APF1 was found to be the most beneficial strain in disease suppression and also growth promotion resulting in 63% dry weight increase compared to untreated control. The study revealed that APF1 and B2G strains are promising strains whose effectiveness under field conditions and their mode of action should be investigated.     

Trypsin inhibitor activity in mature tobacco and tomato plants is mainly induced locally in response to insect attack,wounding and virus infection

Wounding of plants by insects is often mimicked in the laboratory by mechanical means such as cutting or crushing, and has not been compared directly with other forms of biotic stress such as virus infection. To compare the response of plants to these types of biotic and abiotic stress, trypsin inhibitor (TI) activity induced locally and systemically in mature tobacco (Nicotiana tabacum L.) and tomato (Lycopersicon esculentum L.) plants was followed for 12 days. In tobacco, cutting, crushing and insect feeding all induced comparable levels of TI activity of approx. 5 nmol·(mg leaf protein)^?1 in wounded leaves, while tobacco mosaic virus (TMV) infection of tobacco induced 10-fold lower amounts in the infected leaves. In tomato, feeding by insects also led to the induction of a level of TI activity of 5 nmol·(mg leaf protein)^?1. In contrast, both cutting and crushing of tomato leaves induced 10-fold higher amounts. These data show that biotic stress, in the form of insect feeding and TMV infection, and abiotic stress, in the form of wounding, have different effects on local levels of induced TI activity in mature tobacco and tomato plants. Irrespective of the type of wounding, in neither tobacco nor tomato could systemic induction of TI activity be observed in nearby unwounded leaves, which suggests that systemic induction of TI activity in mature tobacco and tomato plants is different from systemic TI induction in seedlings. Wounding of tobacco leaves, however, did increase the responsiveness to wounding elsewhere in the plant, as measured by an increased induction of TI activity.     

Studies on the Chemical Regulation of Alkaloid Biosynthesis in Tobacco Plants

Effect of auxin treatment upon the alkaloid content of Nicotiana was examined using hydroponically grown plants. Nicotine content of Nicotiana tabacum was reduced by the addition of 3-indoleacetic acid or 2, 4-dichlorophenoxyacetic acid to nutrient solution, an the incorporation of nitrate-¹⁵N into nicotine was decreased by the addition of 2, 4-dichloro-phenoxyacetic acid. Contents of nicotine, nornicotine, anabasine and anatabine in Nicotiana glutinosa were decreased by 2, 4-dichlorophenoxyacetic acid added to the nutrient solution. Foliar applications of eleven kinds of synthetic auxins were effective in reducing nicotine content of Nicotiana tabacum and the effectiveness of the compounds seemed to be concerned with their auxin activities. Foliar application of auxin tended to increase the dry weight of stems whereas decreased that of roots, and, moreover, higher content of soluble sugars and lower content of starch in leaves were observed by the treatment. A possibility of a practical application of auxin to reduce the nicotine content of tobacco plants were drawn from this work.     

利迪链霉菌M01对番茄生长、青枯病发病率及根际细菌群落组成的影响

【背景】利迪链霉菌(Streptomyces lydicus)对多种作物均有较好的促生效果,且对病原真菌具有广谱抑制作用,但该菌对细菌性青枯病的防控研究较少。【目的】探究利迪链霉菌M01能否促进番茄生长并抑制番茄青枯病,以及M01对番茄生长的影响是否通过影响根际细菌群落结构实现。【方法】采用温室盆栽试验和扩增子高通量测序技术研究M01对番茄生长、青枯病发病率及根际细菌群落组成的影响。【结果】施用利迪链霉菌M01的番茄植株鲜重、干重、株高、用土壤与作物分析开发(soil and plant analyzer develotrnent, SPAD)方法测量的叶绿素浓度、根系活力和植株P含量比对照分别提高了22.7%、12.5%、16.0%、28.1%、18.4%和17.9%,其中对株高、SPAD值和植株磷含量影响显著(P<0.05)。M01处理延缓了番茄青枯病的发病时间,接种9周后发病率比对照降低了41.8%。此外,M01对番茄根际细菌群落无显著影响(门水平群落组成,P=0.4;属水平群落组成,P=0.4)。【结论】利迪链霉菌M01可促进番茄植株生长并抑制番茄青枯病,利迪链霉菌M01对番茄生长的影响并非通过调控根际细菌群落实现。     

Effect of seaweed concentrate on the establishment and yield of greenhouse tomato plants

Seaweed concentrate prepared fromEcklonia maxima (Osbeck) Papenfuss, when applied as a soil drench, significantly improved the growth of tomato seedlings. Application as a foliar spray had no effect on young plants. In a second experiment SWC-treated plants exhibited early fruit ripening and a total fruit fresh weight increase of 17%. The number of harvested fruit were improved by about 10%. In this instance foliar applied SWC was more beneficial than SWC applied to the soil. The significance of these findings is discussed.author for correspondence     

Overexpression of AtMHX in tobacco causes increased sensitivity to Mg<Superscript>2+</Superscript>, Zn<Superscript>2+</Superscript>, and Cd<Superscript>2+</Superscript> ions,induction of V-ATPase expression,and a reduction in plant size

AtMHX is a vacuolar transporter encoded by a single gene in Arabidopsis. Electrophysiological analysis showed that it exchanges protons with Mg²⁺, Zn²⁺, and Fe²⁺ ions. The physiological impact of AtMHX was examined so far only in tissue-culture grown seedlings of tobacco plants overexpressing this transporter. Here we investigated the impact of AtMHX on growth, response to different metals, and metal accumulation of mature tobacco plants, as well as Arabidopsis plants in which we overexpressed this transporter. The analyses were carried out in hydroponic growth-systems, in which the mineral composition could be effectively controlled, and the metal content of roots could be examined. Transformed tobacco plants showed necrotic lesions and apical burnings upon growth with increased levels of Mg²⁺, Zn²⁺, and Cd²⁺ ions. This suggested that AtMHX can carry in planta not only Mg²⁺ and Zn²⁺ ions, as previously deduced based on observations in tissue-culture, but also Cd²⁺ ions. Transformed plants of both tobacco and Arabidopsis showed a reduction in plant size. However, the overall response of Arabidopsis to AtMHX overexpression was minor. No change was detected in the mineral content of any organ of the transgenic tobacco or Arabidopsis plants. The necrotic lesions in tobacco resembled those seen in plants with perturbed proton balancing, raising the assumption that AtMHX can affect the proton homeostasis of cells. In agreement with this assumption, the transformed tobacco plants had increased expression and activity of the vacuolar H⁺-ATPase. The relative significance of AtMHX for metal and proton homeostasis still has to be elucidated.     

Response of potato grown under non-inductive condition paclobutrazol: shoot growth, chlorophyll content, net photosynthesis, assimilate partitioning, tuber yield, quality, and dormancy

The effect of foliar and soil applied paclobutrazol on potato were examined under non-inductive condition in a greenhouse. Single stemmed plants of the cultivar BP1 were grown at 35(±2)/20(±2) °C day/night temperatures, relative humidity of 58%, and a 16 h photoperiod. Twenty-eight days after transplanting paclobutrazol was applied as a foliar spray or soil drench at rates of 0, 45.0, 67.5, and 90.0 mg active ingredient paclobutrazol per plant. Regardless of the method of application paclobutrazol increased chlorophyll a and b contents of the leaf tissue, delayed physiological maturity, and increased tuber fresh mass, dry matter content, specific gravity, dormancy period of the tubers. Paclobutrazol reduced the number of tubers per plant. A significant interaction between rates and methods of paclobutrazol application were observed with respect to plant height and tuber crude protein content. Foliar application gave a higher rate of net photosynthesis than the soil drench. Paclobutrazol significantly reduced total leaf area and increased assimilate partitioning to the tubers. The study clearly showed that paclobutrazol is effective to suppress excessive vegetative growth, favor assimilation to the tubers, increase tuber yield, improve tuber quality and extend tuber dormancy of potato grown in high temperatures and long photoperiods.     

An Arabidopsis gene with homology to glutathione S-transferases is regulated by ethylene

A cDNA clone obtained from Arabidopsis leaf RNA encodes a 24 kDa protein with homology to glutathione S-transferases (GST). It is most homologous with a tobacco GST (57% identity). In Arabidopsis, expression of GST mRNA is regulated by ethylene. Exposure of plants to ethylene increased the abundance of GST mRNA, while treatment with norbornadiene had the reverse effect. Ethylene had no effect on the mRNA level in ethylene-insensitive etr1 plants. The abundance of this mRNA increased with the age of plants. DNA hybridizations indicate that GSTs are encoded by a large multigene family in Arabidopsis.     

Localization of a 170 kDa myosin heavy chain in plant cells

Summary A polyclonal antibody directed against a 170 kDa myosin heavy chain from lily pollen tubes was employed to (a) assess the cellular distribution of the polypeptide using immunofluorescence methods, and (b) ascertain if similar polypeptides are present in pollen tubes and somatic cells of other species. Fluorescence is associated with particles of various size as well as an amorphous component, and is concentrated in the apical cytoplasm of lily and tobacco pollen tubes. Apical fluorescence is more extensive in lily than in tobacco, which may be related to different streaming patterns and apical zonation seen at the ultrastructural level. In suspension cells of tobacco andArabidopsis, fluorescence is concentrated around the nuclei. Dual localizations indicate that anti-myosin fluorescence may be associated with the presence of actin. Little or no staining was seen in controls consisting of either pre-immune serum or mono-specific IgG that had been preadsorbed with the 170 kDa polypeptide. Immunoblots show that a 170 kDa immunoreactive polypeptide is present in pollen tubes of tobacco andTradescantia virginiana in addition to lily, and in suspension culture cells of tobacco andArabidopsis and extracts of wholeArabidopsis seedlings. Our results show that a conserved 170 kDa myosin heavy chain is present in a variety of monocot and dicot cells. They are also consistent with the presence of multiple myosins in plants in general and pollen tubes in particular.Abbreviations BSA bovine serum albumin - IgG immunoglobulin G - Mf microfilament - Mt microtubule - PBS phosphate-buffered saline - PME 50 mM Pipes, 5mM EGTA - 2mM MgSO₄, pH6.9.     

Expression of Isopentenyl Transferase Gene Controlled by Seed-Specific Lectin Promoter in Transgenic Tobacco Influences Seed Development

The bacterial isopentenyl transferase (ipt) gene involved in cytokinin biosynthesis was fused with a seed-specific lectin promoter from soybean and introduced into tobacco. Under the control of the lectin promoter, the expression of the ipt gene increased cytokinin levels and promoted cell division in the embryo in transgenic tobacco seeds. Compared with controls, the number of plerome cell layers and the cell number of cotyledons and pleromes were significantly increased from 16 DAF (days after flowering); the embryo diameter of transgenic tobacco was enlarged at 16, 19, and 21 DAF (16.1%, 12.7%, and 13.9% increase, respectively). Furthermore, the soluble protein content of the transgenic mature seeds was increased by 9.8–22.2% and the dry weight of transgenic tobacco seeds was increased by 8.8–21.8% compared with that of controls. The transgenic tobacco seedlings also grew quickly and a greater increase in fresh weight compared with controls was observed at 20 and 35 days after germination (average 14% and 8% increase above controls, respectively).