Resistance to Rhizoctonia solani AG‐2‐2 (IIIB) in creeping bentgrass plants transformed with pepper esterase gene PepEST

A pepper esterase (PepEST) gene was introduced into creeping bentgrass (Agrostis stolonifera) by Agrobacterium‐mediated transformation. Purified recombinant PepEST proteins were sufficient to inhibit the growth of the fungal pathogens Rhizoctonia solani AG2‐2 (IIIB) (causing brown patch) and Sclerotinia homoeocarpa (dollar spot), but not the oomycete responsible for pythium blight, Pythium aphanidermatum. PepEST proteins were most effective against R. solani. After genetic transformation of creeping bentgrass with PepEST, the genomic integration of transgenes bar and PepEST was confirmed by Southern blot analysis, and their expression was also validated by northern blot and western blot analyses. Disease severity on R. solani‐inoculated leaves of transgenic plants was <10% compared to ca. 50% in non‐transgenic plants. Microscopic observation of infected leaves indicated that PepEST inhibited the growth of hyphae upon fungal infection.     

Effect of host and inoculum patterns on take-all disease of wheat incidence,severity and disease gradient

The importance of the spatial aspect of epidemics has been recognized from the outset of plant disease epidemiology. The objective of this study was to determine if the host spatial structure influenced the spatio-temporal development of take-all disease of wheat, depending on the inoculum spatial structure. Three sowing patterns of wheat (broadcast sowing, line sowing and sowing in hills) and three patterns of inoculum (uniform, aggregated and natural infestation) were tested in a field experiment, repeated over 2 years. Disease (severity, root disease incidence, plant disease incidence and, when applicable, line and hill incidences) was assessed seven times during the course of each season and the spatial pattern was characterized with incidence-incidence relationships. In the naturally infested plots, disease levels at all measurement scales were significantly higher in plots sown in hills, compared to plots sown in line, which were in turn significantly more diseased than plots with broadcast sowing. Disease aggregation within roots and plants was stronger in line and hill sowing than in broadcast sowing. Analysis of the disease gradient in the artificially infested plots showed that the disease intensified (local increase of disease level) more than it extensified (spatial spread of the disease), the effect of the introduced inoculum was reduced by 95% at a distance of 15 cm away from the point of infestation. Yield was not significantly affected by sowing pattern or artificial infestation.     

Cellular and ultrastructural changes in the seedling roots of upland rice (Oryza sativa) under the stress of two allelochemicals from Ageratina adenophora

Two sesquiterpene‐derivative compounds, 4,7‐dimethyl‐1‐(propan?2‐ylidene)–1,4,4a,8a‐tetrahydronaphthalene‐2,6(1H, 7H)‐dione (DTD) and 6‐hydroxy‐5‐isopropyl‐3,8‐dimethyl?4a,5,6,7,8,8a‐hexahydronaphthalen‐2(1H)–one (HHO), are the major putative allelochemicals of the aqueous leachates of Ageratina adenophora. A laboratory experiment was conducted, using the hydroponic method, to evaluate the cellular and ultrastructural changes in the seedling roots of upland rice under the stress of DTD and HHO. The subsequent changes were observed in the treated upland rice roots in comparison with their controls. The scanning electron microscopy results showed that the DTD‐treated root tip cells turned into an irregular arrangement and shape and that most of them were wizened, with a poor cytoplasm. In the HHO treatment, the root tips had many irregularly shaped cells, with a greater number of sloughing cells, as well as short, wide cells that resulted in spherical and wider, but shorter, roots. At the ultrastructural level, DTD and HHO induced irregularly shaped and lobed nuclei, increased cytoplasmic vacuolation, reduced ribosome density and dictyosomes, and a reduced number of mitochondria in the cells, which indicated limited protein transportation and a reduced capability to export substances for cell development and growth in the upland rice seedling roots. The overall effect of HHO on the upland rice seedlings was more pronounced than that of DTD.     

Apparent digestibility coefficients of selected feed ingredients for juvenile snakehead,Ophiocephalus argus

Apparent digestibility coefficients (ADCs) of dry matter, crude protein, crude lipid, gross energy, phosphorus and amino acids in Peruvian fish meal, poultry by‐product meal, meat and bone meal, spray‐dried blood meal, hydrolysed feather meal, corn gluten meal, soybean meal, peanut meal, cottonseed meal and rapeseed meal were determined for juvenile snakehead (Ophiocephalus argus) with initial mean body weight of 78.1 g. A reference diet and test diets that consisted of a 70 : 30 mixture of the reference diet to test ingredient were used with 5 g kg^?1 Cr₂O₃ as an external indicator. Fish meal, poultry by‐product meal and corn gluten meal had higher ADCs of dry matter, crude protein, and gross energy among ingredients tested. Dry matter ADCs ranged 61.9–81.5% for animal ingredients and corn gluten meal and ranged 52.2–68.0% for soybean meal, peanut meal, cottonseed meal and rapeseed meal. Energy ADCs of ingredients followed similar trends to differences in dry matter digestibility. Protein ADCs of animal and plant ingredients ranged 73.6–92.8% and 75.3–85.6%, respectively. Amino acid ADCs generally reflected protein digestibility. Lipid ADCs were relatively high for the ingredients tested. Phosphorus ADCs of animal and plant ingredients ranged 39.5–65.2% and 38.7–57.1%, respectively.     

Alkali-stabilized Pt-OHx species catalyze low-temperature water-gas shift reactions

We report that alkali ions (sodium or potassium) added in small amounts activate platinum adsorbed on alumina or silica for the low-temperature water-gas shift (WGS) reaction (H(2)O + CO → H(2) + CO(2)) used for producing H(2). The alkali ion-associated surface OH groups are activated by CO at low temperatures (~100°C) in the presence of atomically dispersed platinum. Both experimental evidence and density functional theory calculations suggest that a partially oxidized Pt-alkali-O(x)(OH)(y) species is the active site for the low-temperature Pt-catalyzed WGS reaction. These findings are useful for the design of highly active and stable WGS catalysts that contain only trace amounts of a precious metal without the need for a reducible oxide support such as ceria.     

Cucullanus oceaniensis sp. n. (Nematoda: Cucullanidae) from Pacific eels (Anguilla spp.)

A new species of parasitic nematode, Cucullanus oceaniensis sp. n., is described from the intestine of the giant mottled eel Anguilla marmorata (type host) from Futuna Island (Wallis and Futuna Islands, Polynesia) and from A. marmorata and Anguilla sp. (cf. obscura) from Fiji Islands (Melanesia, South Pacific). The main distinguishing characteristics are the length of spicules (668-1,020 microm), situation of deirids (slightly anterior to the oesophago-intestinal junction) and the excretory pore (some distance posterior to the end of oesophagus), and the arrangement of caudal papillae in the male. It is the third known species of Cucullanus from Oceania and the first one reported from freshwater eels in the region of South Pacific. Cucullanus faliexae Morand et Rigby, 1998 is considered a junior synonym of Cucullanus australiensis Baylis, 1927.