Endophytic Beauveria bassiana increases galling of ‘Rutgers’ tomato roots with Meloidogyne incognita

Beauveria bassiana is endophytic in many plant species and has been shown to protect host plants against insect pests and plant pathogens. However, less is known about its activity against plant-parasitic nematodes. In vitro and plant assays were conducted to determine the effect of B. bassiana 11-98 (Bb) on Meloidogyne incognita (root-knot nematode; RKN). Beauveria bassiana was confirmed as an endophyte in ‘Rutgers’ tomato and colonization patterns of Bb in ‘Rutgers’ (highly susceptible to RKN) were compared with those in ‘Mountain Spring’ (less susceptible to RKN). In greenhouse tests with ‘Rutgers’ at 30 and 60 days after treatment (DAT) with RKN and Bb, there were few differences in plant growth variables among treatments in repeated trials. However, RKN root galling and egg count/root system were enhanced in plants treated with Bb at 60 DAT. In an in vitro assay with egg masses from greenhouse tests, the percentages of hatched eggs, and mobile and immobile nematodes did not differ significantly for RKN and RKN+Bb treatments. The presence of viable Bb from roots was confirmed by collecting egg suspensions from root galls and plating them on selective medium. Colonies of Bb were verified on agar medium, but no parasitism of RKN eggs was observed. Research is needed to investigate factors responsible for increased galling by RKN in the presence of endophytic Bb in ‘Rutgers’ tomato

Sciadopitys verticillata Resin: Volatile Components and Impact on Plant Pathogenic and Foodborne Bacteria

Sciadopitys verticillata (Sv) produces a white, sticky, latex-like resin with antimicrobial properties. The aims of this research were to evaluate the effects of this resin (Sv resin) on bacterial populations and to determine the impact of its primary volatile components on bioactivity. The impact of sample treatment on chemical composition of Sv resin was analyzed using Fourier transform infrared spectroscopy (FTIR) coupled with principal component analysis. The presence and concentration of volatiles in lyophilized resin were determined using gas chromatography/mass spectrometry (GC/MS). Changes in bacterial population counts due to treatment with resin or its primary volatile components were monitored. Autoclaving of the samples did not affect the FTIR spectra of Sv resin; however, lyophilization altered spectra, mainly in the CH and C=O regions. Three primary bioactive compounds that constituted \u3e90% of volatiles (1R-α-pinene, tricyclene, and β-pinene) were identified in Sv resin. Autoclaved resin impacted bacterial growth. The resin was stimulatory for some plant and foodborne pathogens (Pseudomonas fluorescens, P. syringae, and Xanthomonas perforans) and antimicrobial for others (Escherichia coli, Bacillus cereus, Agrobacterium tumefaciens, and Erwinia amylovora). Treatment with either 1R-α-pinene or β-pinene reduced B. cereus population growth less than did autoclaved resin. The complex resin likely contains additional antimicrobial compounds that act synergistically to inhibit bacterial growth

Fungal entomopathogens: new insights on their ecology

An important mechanism for insect pest control should be the use of fungal entomopathogens. Even though these organisms have been studied for more than 100 y, their effective use in the field remains elusive. Recently, however, it has been discovered that many of these entomopathogenic fungi play additional roles in nature. They are endophytes, antagonists of plant pathogens, associates with the rhizosphere, and possibly even plant growth promoting agents. These findings indicate that the ecological role of these fungi in the environment is not fully understood and limits our ability to employ them successfully for pest management. In this paper, we review the recently discovered roles played by many entomopathogenic fungi and propose new research strategies focused on alternate uses for these fungi. It seems likely that these agents can be used in multiple roles in protecting plants from pests and diseases and at the same time promoting plant growth

Terpenoids from Weedy Ricefield Flatsedge (<i>Cyperus iria</i> L.) Are Developmentally Regulated and Stress-Induced, and have Antifungal Properties

Ricefield flatsedge (Cyperus iria L.), a troublesome weed in rice production, actively adapts to ecological niches. In this study, terpenoids were identified as the dominant compounds from organic extracts of C. iria leaves. To understand the role of terpenoid production in plant development and resistance to abiotic and biotic stresses, the dynamics of terpenoid production at different developmental stages, and the regulation of these compounds by stresses were determined. Terpenoid production exhibited temporal and spatial specificity. During vegetative growth, the total concentration of sesquiterpenoids increased and reached a maximum at 70 d after germination, and then decreased until the emergence of inflorescence. Monoterpenoids were only detected from leaves 90 d after germination. During reproductive growth, the total concentration of sesquiterpenoids increased dramatically and mainly accumulated in inflorescences, indicating that the sesquiterpenoids were primarily produced in newly formed and actively growing tissues. The total amount of monoterpenoids, mostly accumulated in flowers, increased until 130 d after germination. Furthermore, accumulation of sesquiterpenoids in leaves was promoted significantly by methyl jasmonate (MeJA) and drought treatment. Infestation by beet armyworm (Spodoptera exigua, BAW) promoted the emission of total sesquiterpenoids significantly and induced the production of more monoterpenoids and sesquiterpenoids specifically. Furthermore, volatiles from C. iria leaves had an anti-fungal effect on Fusarium graminearum. The implications of our findings on the biosynthetic pathways leading to the production of sesquiterpenoids in C. iria as well as their potential as fungicides are discussed

Sciadopitys verticillata Resin: Volatile Components and Impact on Plant Pathogenic and Foodborne Bacteria

Sciadopitys verticillata (Sv) produces a white, sticky, latex-like resin with antimicrobial properties. The aims of this research were to evaluate the effects of this resin (Sv resin) on bacterial populations and to determine the impact of its primary volatile components on bioactivity. The impact of sample treatment on chemical composition of Sv resin was analyzed using Fourier transform infrared spectroscopy (FTIR) coupled with principal component analysis. The presence and concentration of volatiles in lyophilized resin were determined using gas chromatography/mass spectrometry (GC/MS). Changes in bacterial population counts due to treatment with resin or its primary volatile components were monitored. Autoclaving of the samples did not affect the FTIR spectra of Sv resin; however, lyophilization altered spectra, mainly in the CH and C=O regions. Three primary bioactive compounds that constituted &gt;90% of volatiles (1R-&alpha;-pinene, tricyclene, and &beta;-pinene) were identified in Sv resin. Autoclaved resin impacted bacterial growth. The resin was stimulatory for some plant and foodborne pathogens (Pseudomonas fluorescens, P. syringae, and Xanthomonas perforans) and antimicrobial for others (Escherichia coli, Bacillus cereus, Agrobacterium tumefaciens, and Erwinia amylovora). Treatment with either 1R-&alpha;-pinene or &beta;-pinene reduced B. cereus population growth less than did autoclaved resin. The complex resin likely contains additional antimicrobial compounds that act synergistically to inhibit bacterial growth

Thousand Cankers Disease Complex: A Forest Health Issue that Threatens Juglans Species across the U.S.

Thousand Cankers Disease (TCD) is a disease complex wherein the fungus (Geosmithia morbida) is vectored by the walnut twig beetle (WTB, Pityophthorus juglandis). The disease causes mortality primarily of eastern black walnut (Juglans nigra), although other walnut and wingnut (Pterocarya) species are also susceptible. Black walnut is native to the Eastern and Midwestern U.S. but is widely planted in western states. Total standing volume in both urban and forested settings is approximately 96 million cubic meters, and is valued at $539 billion. Although native to the Southwestern U.S., the range of WTB has expanded considerably. The spread of G. morbida coincides with that of WTB. TCD was introduced into Tennessee in 2010, and has spread to seven eastern states. Trees infected with TCD exhibit drought-like symptoms, making field detection difficult without molecular and/or morphological methods. The recently sequenced G. morbida genome will provide valuable research tools focused on understanding gene interactions between organisms involved in TCD and mechanisms of pathogenicity. With no chemical treatments available, quarantine and sanitation are preeminent options for slowing the spread of TCD, although biological control agents have been discovered. High levels of black walnut mortality due to TCD will have far-reaching implications for both eastern and western states