Potential for phytoextraction of137 Cs from a contaminated soil

Potential for phytoremediation of a soil contaminated with radiocesium was investigated in three phases: (1) hydroponic screening for plant species capable of accumulating elevated levels of cesium in shoots, (2) investigation of several amendments for their potential to increase the bioavailability of ¹³⁷Cs in the contaminated soil, and (3) bioaccumulation of radiocesium in shoots of plants grown in¹³⁷ Cs-contaminated soil.The bioaccumulation ratio for Cs in shoots of hydroponically grown plants ranged between 38 and 165. From solution, dicot species accumulated 2- to 4-fold more cesium in shoots than grasses. In studies investigating the bioavailability of ¹³⁷Cs in aged contaminated soil, ammonium salts were found to be the most effective desorbing agents, releasing approximately 25% of the¹³⁷ Cs. The extent of ¹³⁷Cs desorption from the soil increased with ammonium concentration up to 0.2 M. In a pot study conducted in a greenhouse, there was significant species-dependent variability in the ability to accumulate ¹³⁷Cs in the shoot from contaminated soil. The ability to accumulate ¹³⁷Cs from the soil increased in the order: reed canarygrass (Phalaris arundinacea) < Indian mustard (Brassica juncea) < tepary bean (Phaseolus acutifolius)< cabbage (B. oleracea var. capitata). It was also found that addition of NH₄NO₃ solution to the soil elicited a two- to twelve-fold increase in ¹³⁷Cs accumulation in the shoot. The greatest amount of ¹³⁷Cs (40 Bq g^-1 dw) was removed in shoots of cabbage grown in contaminated soil amended with 80 mmols NH₄NO₃ kg^-1 soil. Bioaccumulation ratios of 2–3 were obtained with the best performing plant species. These values are significantly greater than those previously reported in the literature (usually <0.1) for plants grown on aged contaminated soil. These results indicate that careful species selection along with amendments that increase the bioavailability of¹³⁷ Cs in the soil could greatly enhance the prospects for the use of plants to remediate ¹³⁷Cs-contaminated soils.     

Effects of colonization of a bacterial endophyte,Azospirillum sp. B510, on disease resistance in tomato

A plant growth-promoting bacteria, Azospirillum sp. B510, isolated from rice, can enhance growth and yield and induce disease resistance against various types of diseases in rice. Because little is known about the interaction between other plant species and this strain, we have investigated the effect of its colonization on disease resistance in tomato plants. Treatment with this strain by soil-drenching method established endophytic colonization in root tissues in tomato plant. The endophytic colonization with this strain-induced disease resistance in tomato plant against bacterial leaf spot caused by Pseudomonas syringae pv. tomato and gray mold caused by Botrytis cinerea. In Azospirillum-treated plants, neither the accumulation of SA nor the expression of defense-related genes was observed. These indicate that endophytic colonization with Azospirillum sp. B510 is able to activate the innate immune system also in tomato, which does not seem to be systemic acquired resistance.     

Effects on plant growth and root-knot nematode infection of an endophytic GFP transformant of the nematophagous fungus Pochonia chlamydosporia

Pochonia chlamydosporia (Pc123) is a fungal parasite of nematode eggs which can colonize endophytically barley and tomato roots. In this paper we use culturing as well as quantitative PCR (qPCR) methods and a stable GFP transformant (Pc123gfp) to analyze the endophytic behavior of the fungus in tomato roots. We found no differences between virulence/root colonization of Pc123 and Pc123gfp on root-knot nematode Meloidogyne javanica eggs and tomato seedlings respectively. Confocal microscopy of Pc123gfp infecting M. javanica eggs revealed details of the process such as penetration hyphae in the egg shell or appressoria and associated post infection hyphae previously unseen. Pc123gfp colonization of tomato roots was low close to the root cap, but increased with the distance to form a patchy hyphal network. Pc123gfp colonized epidermal and cortex tomato root cells and induced plant defenses (papillae). qPCR unlike culturing revealed reduction in fungus root colonization (total and endophytic) with plant development. Pc123gfp was found by qPCR less rhizosphere competent than Pc123. Endophytic colonization by Pc123gfp promoted growth of both roots and shoots of tomato plants vs. uninoculated (control) plants. Tomato roots endophytically colonized by Pc123gfp and inoculated with M. javanica juveniles developed galls and egg masses which were colonized by the fungus. Our results suggest that endophytic colonization of tomato roots by P. chlamydosporia may be relevant for promoting plant growth and perhaps affect managing of root-knot nematode infestations.     

Oviposition preference and larval performance and behavior of <Emphasis Type="Italic">Trichoplusia ni</Emphasis> (Lepidoptera: Noctuidae) on host and nonhost plants

We investigated the female oviposition preference and larval performance and behavior of Trichoplusia ni (Hubner) on cabbage, tomato, soybean (host plants), and wormseed (nonhost plant) in laboratory experiments. In addition, we investigated the role of trichomes in the oviposition of females. Females oviposited more often on cabbage than on tomato, soybean, or wormseed plants. Tomato was the second most preferred plant, followed by soybean and wormseed. Neonate larvae gained more weight on cabbage and tomato than on soybean or wormseed, while second-instar larvae grew better on cabbage than on tomato, soybean, or wormseed. The least growth of neonate larvae occurred on wormseed plants. The orientation of neonate and second-instar larvae to cabbage, tomato, soybean, and wormseed did not differ significantly. Neonate larvae settled equally on leaf discs of cabbage, tomato, soybean, and wormseed, while most second-instar larvae settled on leaf discs of cabbage in comparison with the other plants after 24 h of release. The foliar area consumed by neonate larvae was quite similar among plants, but second-instar larvae consumed more cabbage than tomato, soybean, or wormseed. Comparing different types of leaves, females oviposited more often on mature than young leaves of tomato, soybean, and wormseed. In contrast, females did not show any preference for ovipositing on young or mature leaves of cabbage. In general, we found that the density or length of nonglandular and glandular trichomes of tomato, soybean, and wormseed plants negatively affected oviposition of T. ni females.     

Mycovirus effect on the endophytic establishment of the entomopathogenic fungus Tolypocladium cylindrosporum in tomato and bean plants

Two endophytic strains of the entomopathogenic fungus Tolypocladium cylindrosporum, originally isolated from the grass Festuca rubra, were artificially inoculated in tomato and bean plants. Strains 11-1L and 11-0BR were isolated from asymptomatic leaf fragments of both plant species at 3, 7, 14, 21, and 35 days after their inoculation. The percentage of leaf fragments infected by the fungus in inoculated leaves decreased at each sampling time, and no systemic colonization of the plants occurred. The two T. cylindrosporum strains tested were isogenic, differing in the infection by the victorivirus TcV1, harboured by strain 11-1L, but not by 11-0BR. The percentage of infected leaf fragments in leaves inoculated with the virus infected strain was greater in bean than in tomato plants, while the virus-free strain was more successful in tomato than in bean plants. This result suggests that the mycovirus infection can affect the adaptation of T. cylindrosporum to particular host plants.     

Oviposition induced volatiles in tomato plants

In response to attack by herbivorous insect, plants produce semiochemicals which act to attract their natural enemies. Recent work on plant volatile compounds has shown that they may play multiple roles as communication signals and defense agents. Here we measured the volatile profile of tomato plants with and without oviposition by the herbivore moth, Tuta absoluta. We used solid phase micro extraction (SPME) sample pre-concentration techniques combined with gas chromatography-mass spectrometry. We have found that different volatile profiles emitted from tomato plants with oviposition by T. absoluta compared to control plants. Hexanal, (Z)-3-hexen-1-ol and an unidentified compound were isolated only from tomato plants with T. absoluta eggs. (Z)-3-hexen-1-ol was identified only from tomato plants with T. absoluta eggs that were laid three days earlier. The percentage of sesquiterpenes (e.g. δ-elemene) has been found to increase in the headspace of tomato plants with oviposition. These results in respect to indirect defense of tomato plants to T. absoluta are discussed.     

Proteinase Inhibitor-inducing Factor in Plant Leaves: A Phylogenetic Survey

Thirty-nine plant species representing 20 families from the four major divisions of plants were surveyed for the presence of proteinase inhibitor-inducing factor activity in leaves or other tissues. Tissue juices were assayed for their capacity to induce accumulation of proteinase inhibitor I in excised tomato (Lycopersico esculentum) leaves. In tissues of only 2 of the 39 species was proteinase inhibitor-inducing factor-like activity not found. The activity was absent in cabbage leaves and celery stalks. Fruiting bodies from one of three fungi genera assayed contained exceptionally large quantities of proteinase inhibitor-inducing factor-like activity. Extracts from Agraricus campestris fruiting bodies contained over 20 times more activity than tomato leaf juice. The survey confirms that substances with proteinase inhibitor-inducing factor-like activity are widespread in the plant kingdom.     

Some fungal endophytes from vegetable crops and their anti-oomycete activities against tomato late blight

AIMS: To isolate endophytic fungi from vegetable plants and examine their in vivo anti-oomycete activity against Phytophthora infestans in tomato plants. METHODS AND RESULTS: Endophytic fungi were isolated from surface-sterilized plant tissues and anti-oomycete activity was measured by in vivo assay using tomato seedlings. Endophytic fungi showing potent anti-oomycete activity were identified by morphological characteristics and nuclear ribosomal ITS1-5.8S-ITS2 sequence analysis. A total of 152 isolates were obtained from 66 healthy tissue samples of cucumber, red pepper, tomato, pumpkin and Chinese cabbage and the fermentation broths of 23 isolates showed potent in vivo anti-oomycete activity against tomato late blight with control values over 90%. The Fusarium oxysporum strain EF119, which was isolated from roots of red pepper, showed the most potent disease control efficacy against tomato late blight. In dual-culture tests, it inhibited the growth of Pythium ultimum, P. infestans and Phytophthora capsici. CONCLUSIONS: Among endophytic fungi isolated from healthy tissues of vegetable plants, F. oxysporum EF119 showed the most potent in vivo anti-oomycete activity against tomato late blight and in vitro anti-oomycete activity against several oomycete pathogens. SIGNIFICANCE AND IMPACT OF THE STUDY: Endophytic fungi showing anti-oomycete activity in vitro and in vivo may be used as biocontrol agents particularly of tomato late blight.     

Cadmium and Nickel Toxicity for <Emphasis Type="Italic">Sinapis alba</Emphasis> Plants Inoculated with Endophytic Strains of <Emphasis Type="Italic">Bacillus subtilis</Emphasis>

We studied the effect of cadmium and nickel on Sinapis alba L. plants inoculated with endophytic strains of Bacillus subtilis. It was shown that treatment of S. alba seeds with endophytic strains of bacteria B. subtilis improves plant resistance to the toxic effect of cadmium and nickel and reduces manifestation of oxidative stress in the presence of higher levels of metal ions in the above-ground part of plants. Anti-stress effect and the ability of endophytic strains of B. subtilis to intensify uptake of cadmium and nickel ions by S. alba plants may be used for phytoextraction of heavy metals and stimulation of plant growth in contaminated areas.     

Relations entre la tolérance ou la sensibilité à la salinité lors de la germination des semences et les composantes de la nutrition en sodium

Adsorption, absorption and translocation of sodium were compared in three species showing an ascending degree in tolerance to salinity: red cabbage (tolerant) shows higher Root Cationic Exchange Capacity than tomato (sensitive) or radish (intermediate). At low NaCl concentrations, tomato accumulates the greatest quantities of sodium; but Na⁺ translocation remains proportional to the quantity absorbed in the three plants. At high salt concentrations, diffusive phenomena explain similar accumulation in every plant, but red cabbage quickly localises 50% of Na⁺ amount in cotyledons, while this element stays stored in tomato roots. The consequence of these three nutrition phases was discussed in relation to the behaviour observed at the germination time of these same plants.      

Induction of metabolite organic compounds by mutualistic endophytic fungi to reduce the greenhouse whitefly Trialeurodes vaporariorum (Westwood) infection on tomato

Background and aims

Six mutualistic endophytic fungi that are known to colonize the endorhiza have shown biological control properties against plant-parasitic nematodes. In this study we aim to investigate the potential of these endophytic fungi to reduce the phloem-feeding insect Trialeurodes vaporariorum (Westwood) on tomato.

Methods

To determine the host plant choice of T. vaporariorum, the total number of insects present on each plant was counted daily for 10 days, and then the second leaf below the shoot apex were examined for its chlorophyll content index (CCI).To separate and quantify the active compounds produced in the tomato leaves, a reversed phase high liquid chromatography (RP-HPLC) analysis was performed.

Principle results

A greenhouse choice test showed that Trichoderma atroviride strain MT-20, T. atroviride strain S-2 and Fusarium oxysporum strain 162 (Fo162) reduced the number of greenhouse whiteflies fifty percent when compared to the untreated control during ten days after insect release. The highest level of biocontrol activity was attained with Fo162. The strains MT20, S-2, and Fo162 all demonstrated acropedal induction of resistance to the insects. The isolate Fusarium sp. strain Bonn-7 enhanced plant growth. The negative effect on insect attraction to the leaves of the endophyte treated plants was not associated with leaf altered chlorophyll content. RP-HPLC analysis revealed that inoculation of the fungus Fo162 induced a change in the accumulation of specific organic compounds in the tomato leaves that could be the cause of insect repellence.

Conclusions

This study demonstrated the high potential of mutualintic endophytic fungi, in particular of Fo162, to induce resistance in tomato against the phloemfeeding T. vaporariorum.     

Tiankengomelania guangxiense,gen. et sp. nov., a dark septate endophytic fungus,promotes the growth of the medicinal orchid Dendrobium officinale

Dendrobium officinale (Orchidaceae) is a traditional Chinese medicinal plant. Its growth is slow, however many dark septate endophytic fungi (DSEs) are considered useful to plant growth and as biocontrol agents against plant pathogens. The goals of this study were to identify a new DSE and evaluate its plant-growth promotion characteristics. Based on morphological and molecular phylogenetic evidence, a DSE fungal strain TK815 isolated from Dashiwei Tiankengs in Leye county Guangxi Province, China, was classified as a novel genus in the order Cheatothyriales, namely Tiankengomelania gen. nov. typified with T. guangxiense sp. nov. Tiankengomelania guangxiense TK815 can significantly promote the growth of D. officinale in stem length (11.25%), seedling height (16.97%), root length (10.34%), and dry weight (41.05%). This study discovered, described, and illustrated a new DSE fungus, and evaluated its biological function in contributing to the growth and production of the Chinese medicinal plant D. officinale.     

Highly Diverse Endophytic and Soil Fusarium oxysporum Populations Associated with Field-Grown Tomato Plants

The diversity and genetic differentiation of populations of Fusarium oxysporum associated with tomato fields, both endophytes obtained from tomato plants and isolates obtained from soil surrounding the sampled plants, were investigated. A total of 609 isolates of F. oxysporum were obtained, 295 isolates from a total of 32 asymptomatic tomato plants in two fields and 314 isolates from eight soil cores sampled from the area surrounding the plants. Included in this total were 112 isolates from the stems of all 32 plants, a niche that has not been previously included in F. oxysporum population genetics studies. Isolates were characterized using the DNA sequence of the translation elongation factor 1α gene. A diverse population of 26 sequence types was found, although two sequence types represented nearly two-thirds of the isolates studied. The sequence types were placed in different phylogenetic clades within F. oxysporum, and endophytic isolates were not monophyletic. Multiple sequence types were found in all plants, with an average of 4.2 per plant. The population compositions differed between the two fields but not between soil samples within each field. A certain degree of differentiation was observed between populations associated with different tomato cultivars, suggesting that the host genotype may affect the composition of plant-associated F. oxysporum populations. No clear patterns of genetic differentiation were observed between endophyte populations and soil populations, suggesting a lack of specialization of endophytic isolates.     

Endophytic bacteria of the rock-dwelling cactus Mammillaria fraileana affect plant growth and mobilization of elements from rocks

Mammillaria fraileana is a major pioneer, small cactus that harbors endophytic bacteria that have plant growth-promoting traits, including rock-weathering capacity. Our working hypothesis was that this functional group of endophytic bacteria assists in establishing pioneer plants on rocks. When these endophytic bacteria were inoculated on seedlings grown in rock substrate, mobilization of elements from the substrate increased at variable levels across combinations of substrates and inoculants. In plants grown in the rhyodacite substrate, where these cacti naturally grow, increased mobilization occurred in plants inoculated with several strains. Promotion of plant growth, manifested as an increase in dry weight, was greater in cacti inoculated with Enterobacter sakazakii M2PFe. Accumulation of nocturnal acids, indicating photosynthesis by crassulacean acid metabolism, was superior in plants inoculated with the endophytes Azotobacter vinelandii M2Per and Pseudomonas putida M5TSA. Inoculation with endophytes can stimulate plant growth of M. fraileana by mobilizing elements from rock, which can lead to higher photosynthetic activity and accumulation of biomass. Inoculation with P. putida M5TSA also led to accumulation of more total nitrogen than plants inoculated with a control nitrogen-fixing bacteria. Evidence of endophytic colonization is provided after initial inoculation of seedlings and re-isolation and sequencing of 16S DNA of recovered bacteria from developing disinfected plants. The associative interaction between pioneer cacti and their bacterial endophytes enable the host plants to grow in places where plants do not normally grow. Through colonization and establishment of pioneer plants, soil is created, which facilitates colonization by other desert species and contributes to the diversity of dry lands.     

番茄内生菌的分离鉴定及菌株FQ-G3抗病促生特性

由灰葡萄孢(Botrytis cinerea)引起的灰霉病是番茄生产中最重要的病害之一,当前使用的杀菌剂因药物残留、病原菌抗药性及食品安全等原因逐渐受到限制。因此,利用拮抗微生物的生物防治逐渐成为灰霉病防控的有效策略。【目的】从番茄植株体内筛选具有抗病促生特性内生菌株并对其生防潜力进行评估,为开发番茄灰霉病生物防治新策略提供理论依据。【方法】采用组织分离法在番茄植株不同部位分离出内生细菌、真菌,结合16SrRNA和ITS序列分析,对候选菌株进行初步鉴定;通过菌株对峙培养、果实离体接种筛选对灰葡萄孢具有拮抗活性的内生菌;进一步测定菌株分泌生长素、嗜铁素的能力及其对拟南芥和番茄幼苗生长的促生特性。【结果】从番茄植株不同部位共分离出72株内生细菌和31株内生真菌,通过平板对峙法筛选出1株对多种病原菌具有较好抑菌活性的内生细菌FQ-G3,分子鉴定为Bacillus velezensis。FQ-G3对灰葡萄孢抑菌率达80.93%,并显著抑制灰葡萄孢在番茄果实上的扩展。该菌株能够分泌生长素、蛋白酶和嗜铁素,且对拟南芥、番茄幼苗具有明显的促生效果。【结论】本研究表明分离自番茄植株的内生菌FQ-G3具...     

Selection of Specific Endophytic Bacterial Genotypes by Plants in Response to Soil Contamination

Plant-bacterial combinations can increase contaminant degradation in the rhizosphere, but the role played by indigenous root-associated bacteria during plant growth in contaminated soils is unclear. The purpose of this study was to determine if plants had the ability to selectively enhance the prevalence of endophytes containing pollutant catabolic genes in unrelated environments contaminated with different pollutants. At petroleum hydrocarbon contaminated sites, two genes encoding hydrocarbon degradation, alkane monooxygenase (alkB) and naphthalene dioxygenase (ndoB), were two and four times more prevalent in bacteria extracted from the root interior (endophytic) than from the bulk soil and sediment, respectively. In field sites contaminated with nitroaromatics, two genes encoding nitrotoluene degradation, 2-nitrotoluene reductase (ntdAa) and nitrotoluene monooxygenase (ntnM), were 7 to 14 times more prevalent in endophytic bacteria. The addition of petroleum to sediment doubled the prevalence of ndoB-positive endophytes in Scirpus pungens, indicating that the numbers of endophytes containing catabolic genotypes were dependent on the presence and concentration of contaminants. Similarly, the numbers of alkB- or ndoB-positive endophytes in Festuca arundinacea were correlated with the concentration of creosote in the soil but not with the numbers of alkB- or ndoB-positive bacteria in the bulk soil. Our results indicate that the enrichment of catabolic genotypes in the root interior is both plant and contaminant dependent.     

HOST PLANT PREFERENCES OF BEMISIA TABACI GENNADIUS

Abstract The preferences of Bemisia tabaci Gennadius for five host plants: poinsettia, tomato, cabbage, sweet potato and flowering Chinese cabbage, was tested using a Y-tube olfactometer and a desiccator in the laboratory. The results show that B. tabaci adults were attracted by the odors of the five plants. The order of preference was poinsettia > flowering Chinese cabbage > sweet potato > cabbage > tomato. Preference was extremely significant between poinsettia and the other four plants, and between flowering Chinese cabbage, cabbage and tomato. There was no significant difference in preference for flowering Chinese cabbage and sweet potato, sweet potato, cabbage and tomato or between cabbage and tomato.     

烟粉虱对不同寄主植物定向行为研究(英文)

采用Y形嗅觉仪测定法和干燥器测定法研究了烟粉虱对一品红、地瓜、菜心、番茄和包菜 5种植物的定向行为 ,结果表明 :(1) 5种植物对烟粉虱均有引诱作用 ;(2 )不同种植物对烟粉虱有不同的引诱作用 ,其引诱力的顺序为 :一品红 >菜心 >地瓜 >包菜 >蕃茄 ,方差分析表明 :烟粉虱对 5种植物的定向行为差异极显著 ,LSD法测定进一步表明 :一品红与其余 4种植物差异极显著 ;菜心与包菜和番茄的差异达到显著水平 ,而与地瓜无显著差异 ;地瓜与包菜、番茄之间以及包菜与番茄之间均无差异显著性。     

Dark Septate Root Endophytic Fungus <Emphasis Type="Italic">Nectria haematococca</Emphasis> Improves Tomato Growth Under Water Limiting Conditions

The ascomycetous dark septate endophytic (DSE) fungi characterized by their melanized hyphae can confer abiotic stress tolerance in their associated plants in addition to improving plant growth and health. In this study inoculation of the DSE fungus Nectria haematococca Berk. & Broome significantly improved all the plant growth parameters like the plant height, stem girth, leaf characteristics and plant biomass of drought-stressed tomato. Root characters like the total root length, primary root diameter, 2nd order root number and diameter, root hair number and length were also significantly influenced by the fungal inoculation. Nevertheless, N. haematococca inoculation did not affect root colonization by native arbuscular mycorrhizal (AM) fungi and no significant correlation existed between the AM and DSE fungal variables examined. The proline accumulation in shoots of N. haematococca inoculated plants was significantly higher than uninoculated plants. The present study clearly indicates for the first time the ability of the DSE fungus, N. haematococca in inducing the drought stress tolerance and promoting the growth of the host plant under water stress.