Simple and economical biosensors for distinguishing Agrobacterium-mediated plant galls from nematode-mediated root knots.

Agrobacterium-mediated plant galls are often misdiagnosed as nematode-mediated knots, even by experts, because the gall symptoms in both conditions are very similar. In the present study, we developed biosensor strains based on agrobacterial opine metabolism that easily and simply diagnoses Agrobacterium-induced root galls. Our biosensor consists of Agrobacterium mannitol (ABM) agar medium, X-gal, and a biosensor. The working principle of the biosensor is that exogenous nopaline produced by plant root galls binds to NocR, resulting in NocR/nopaline complexes that bind to the promoter of the nopaline oxidase gene (nox) operon and activate the transcription of noxB-lacZY, resulting in readily visualized blue pigmentation on ABM agar medium supplemented with X-gal (ABMX-gal). Similarly, exogenous octopine binds to OccR, resulting in OoxR/octopine complexes that bind to the promoter of the octopine oxidase gene (oox) operon and activate the transcription of ooxB-lacZY, resulting in blue pigmentation in the presence of X-gal. Our biosensor is successfully senses opines produced by Agrobacterium-infected plant galls, and can be applied to easily distinguish Agrobacterium crown gall disease from nematode disease.

Home economics in an oak gall: behavioural and chemical immune strategies against a fungal pathogen in Temnothorax ant nests.

Nest architecture is a fundamental character shaping immune strategies of social insects. The arboreal ant Temnothorax unifasciatus nests in cavities such as oak galls where the entire colony lives in a unique small chamber. In these conditions, physiological and behavioural strategies likely prevail over compartmentalisation and are presumably tuned with colony size. We designed two experiments to study chemical and behavioural immune strategies against the entomopathogenic fungus Metarhizium anisopliae in colonies of different sizes. First, we compared spore germination and length of germinal tubes inside artificial nests, designed to impede the contact between the ants and the fungus, in colonies of different size. In the absence of direct contact, Temnothorax unifasciatus colonies inhibit fungal growth inside their nests, presumably through volatile compounds. The analysis revealed a positive correlation between fungistatic activity and colony size, indicating that workers of smaller colonies do not invest a higher per capita effort in producing such substances compared to larger colonies. Second, we performed a removal experiment of contaminated and non-contaminated items introduced inside the nests of colonies of different size. Small colonies challenged with contaminated fibres showed an increased removal of all the items (both contaminated and non-contaminated) compared to small colonies challenged with non-contaminated fibres only. Conversely, larger colonies moved items regardless of the presence of the spores inside the nest. Colony size qualitatively affected removal of waste items showing a pathogen elicited reaction in small colonies to optimise the reduced workforce, while the removal behaviour in larger colonies revealed to be expressed constitutively.

Constraints on the evolution of resistance to gall flies in Solidago altissima: resistance sometimes costs more than it is worth.

Plant populations frequently maintain submaximal levels of resistance to natural enemies, even in the presence of substantial genetic variation for resistance. Identifying constraints on the evolution of increased resistance has been a major goal of researchers of plant-herbivore interactions. In a glasshouse study, we measured relative costs and benefits of resistance of tall goldenrod (Solidago altissima) to the gall-inducing tephritid Eurosta solidaginis. We exposed multiple ramets of 26 goldenrod genets to nutrient or shade stress and to oviposition by E. solidaginis. The presence of a gall cost a ramet an average of 1743 seeds, but the cost differed 10-fold across environments. Plant genets varied widely for an induced 'hypersensitive' response in which meristem cells become necrotic and kill E. solidaginis hatchlings before gall induction. There was no evidence that this highly effective resistance trait carried an allocation cost. However, the response carried a risk of autotoxicity, as necrosis killed the apex of 37% of the ungalled ramets. On average, a damaged apex cost each ramet 5015 seeds. Autotoxicity may constrain the resistance of S. altissima to an intermediate level, and variation in environmental conditions may alter the relative costs and benefits of resistance and tolerance, thus maintaining genetic variation within goldenrod populations.

Parasitoids of the eucalyptus gall wasp Leptocybe invasa (Hymenoptera: Eulophidae) in China.

Leptocybe invasa Fisher & La Salle (Hymenoptera, Eulophidae) is an invasive pest in Eucalyptus plantations throughout the world. Potential biological control agents for L. invasa were investigated in the Fujian, Guangdong, Hainan, Guangxi, Jiangxi, and Sichuan provinces of China, where Eucalyptus spp. have been severely damaged by the eucalyptus gall wasp. Three hymenopteran parasitoids of L. invasa were identified: Quadrastichus mendeli Kim & La Salle (Eulophidae), Aprostocetus causalis La Salle & Wu (Eulophidae), and Megastigmus viggianii Narendran & Sureshan (Torymidae); M. viggianii is newly recorded in China. The percentages of parasitization by Q. mendeli, A. causalis, and M. viggianii were 2.96%-19.53%, 2.30%-26.38%, and 24.93%, respectively. The longevity and body length of females were significantly greater than for males in A. causalis and M. viggianii. No males of Q. mendeli were found in China. These parasitoids could be used as biological agents for L. invasa in China.

Antioxidant activities of leaf galls extracts of Terminalia chebula (Gaertn.) Retz. (Combretaceae).

BACKGROUND: Free radicals are implicated in several metabolic diseases and the antioxidant therapy has gained an utmost importance in the treatment. The medicinal properties of plants have been investigated and explored for their potent antioxidant activities to counteract metabolic disorders. In this study, the chemical composition and free radical scavenging potential of leaf gall extracts (ethanol, petroleum ether, chloroform and aqueous) of Terminelia chebula is evaluated, which is extensively used in the preparation of traditiona medications to treat various metabolic diseases. METHODS: The presences of phenolics, flavonoids, triterpens, saponins, glycosides, phytosterols, reducing sugars were identified in the extracts according to standard procedures. The free radical scavenging activities of the extract were also analysed by standard procedures. RESULTS: The methanol extract had the highest total phenolic and flavonoid content. The antioxidant activities of leaf gall extracts were examined using diphenylpicrylhydrazyl (DPPH), Super oxide radical scavenging, Hydroxyl scavenging and ferric reducing power (FRAP) methods. In all the methods, the ethanolic extract showed higher free radical scavenging potential than all the other extracts. CONCLUSIONS: As the higher content of both total phenolics and flavonoids were found in the ethanolic extract, so the significantly high antioxidant activity can be positively correlated to the high content of total polyphenols/flavonoids of the ethanol extract. The results of this study confirm the folklore use of T. chebula leaves gall extracts as a natural antioxidant and justify its ethnobotanical use. Further, the results of antioxidant properties encourage the use of T. chebula leave gall extracts for medicinal health, functional food and nutraceutical applications.

Synchronism between Aspidosperma macrocarpon Apocynaceae resources allocation and the establishment of the gall inducer Pseudophacopteron sp. Hemiptera: Psylloidea / Sincronismo de Aspidosperma macrocarpon Apocynaceae entre la asignación de recursos y el establecimiento del inductor de agallas Pseudophacopteron sp. Hemiptera: Psylloidea

The joint interpretation of phenology and nutritional metabolism provides important data on plant tissues reactivity and the period of gall induction. A population of Aspidosperma macrocarpon Apocynaceae with leaf galls induced by a Pseudophacopteron sp. Psylloidea was studied in Goiás state, Brazil. Assuming the morphological similarity between host leaves and intralaminar galls, a gradient from non-galled leaves towards galls should be generated, establishing a morpho-physiological continuum. The phenology, infestation of galls, and the carbohydrate and nitrogen contents were monthly evaluated in 10-20 individuals, from September 2009 to September 2010. Our objective was to analyze the nutritional status and the establishment of a physiological continuum between the galls and the non-galled leaves of A. macrocarpon. The period of leaf flushing coincided with the highest levels of nitrogen allocated to the new leaves, and to the lowest levels of carbohydrates. The nutrients were previously consumed by the growing leaves, by the time of gall induction. The levels of carbohydrates were higher in galls than in non-galled leaves in time-based analyses, which indicateed their potential sink functionality. The leaves were infested in October, galls developed along the year, and gall senescence took place from March to September, together with host leaves. This first senescent leaves caused insect mortality. The higher availability of nutrients at the moment of gall induction was demonstrated and seems to be important not only for the establishment of the galling insect but also for the responsiveness of the host plant tissues.

La interpretación conjunta de la fenología y el metabolismo nutricional proporciona datos importantes sobre la reacción de tejidos vegetales y el período de inducción de agallas. En el estado de Goiás, Brasil se estudió una población de Aspidosperma macrocarpon Apocynaceae con agallas foliares inducidas por un Pseudophacopteron sp. Psylloidea. Suponiendo que la similitud morfológica entre las hojas del hospedero y las agallas intralaminares genera un gradiente de hojas sin agallas hacia hojas con agallas, se establece un continuo morfo-fisiológico. La fenología, la infestación de las agallas y el contenido de carbohidratos y nitrógeno se evaluaron mensualmente en 10-20 individuos, de septiembre 2009 a septiembre 2010. El objetivo fue analizar el estado nutricional y el establecimiento de un continuo fisiológico entre las hojas que producen agallas y las hojas sin agallas de A. macrocarpon. El período de emergencia de hojas coincidió con los niveles más altos de nitrógeno en las hojas nuevas, y los niveles más bajos de carbohidratos.Los nutrientes se consumieron previamente por las hojas en crecimiento, en el momento de inducción de las agallas. Los niveles de carbohidratos fueron más altos en las hojas con agallas que en aquellas sin agallas, en análisis basados en tiempo, lo que indica su ciclo de funcionalidad potencial. Las hojas hospederas se infestaron en octubre, el desarrollo y la senescencia de las agallas se llevó a cabo entre marzo y septiembre, en las hojas hospederas. Estas primeras hojas senescentes causaron mortalidad de insectos. Hay mayor disponibilidad de nutrientes en el momento de la inducción de las agallas y parece ser importante no sólo para el establecimiento del insecto que produce agallas, sino también para la capacidad de respuesta de los tejidos de la planta hospedera.

Assessment of antibacterial properties and the active ingredient of plant extracts and its effect on the performance of crucian carp (Carassius auratus gibelio var. E'erqisi, Bloch).

BACKGROUND: In this study, the antibacterial properties and active ingredient of plant extracts and its effect on the performance of crucian carp (Carassius auratus gibelio var. E'erqisi, Bloch) were assessed. RESULTS: The transmission electron microscopy and flow cytometric analysis showed that the antibacterial activity of plant extracts is due to the disruption of the cell membrane and the leakage of cytoplasmic contents. The UPLC-MS/MS analysis showed that the contents of gallic acid, (-)-epigallocatechin, (+)-catechin, (-)-epigallocatechin gallate, (-)-epicatechin gallate, aloe-emodin, rhein, emodin, chrysophanol, and physcion, were 5.27%, 3.30%, 1.08%, 19.32%, 5.46%, 0.23%, 0.56%, 1.28%, 0.75% and 0.39% in plant extracts, respectively. Results of feeding experiment showed that feeding crucian carp with 1.0% and 2.0% plant extracts significantly enhanced specific growth rate, serum total protein, lysozyme, catalase and superoxide dismutase activities, and decreased the feed conversion rate, malondialdehyde contents and the mortality rate (P < 0.05). CONCLUSION: It can be concluded that plant extracts added to fish feed can act as natural antimicrobial and immunostimulants to prevent pathogenic infection, enhance immune response, and promote growth of the fish.

Crown gall: economic importance and control.

Many plants of economic importance are possible hosts for Agrobacterium tumefaciens, the causal organism of the crown gall tumor disease. Damage has been reported on stone fruit (Australia), vineyard (Hungary, Bulgaria), lettuce (Brasil) ... In Western-Europe, crown gall seems to be of less economic importance for plants growing in the open air. However, plants cultivated in greenhouses have a greater chance to be tumorized, because of the more favourable circumstances for tumor induction. Modern treatments are based on the inactivation or killing of the tumorigenic organism at the time of the wounding of the host plants.