Virtual brain endocast of Antifer (Mammalia: Cervidae), an extinct large cervid from South America

A diverse fossil record of Cervidae (Mammalia) has been documented in the South American Pleistocene, when these animals arrived during the Great American Biotic Interchange. Using computed tomography-scanning techniques, it is possible to access the endocranial morphology of extinct species. Here, we studied the brain endocast of the extinct late Pleistocene cervid Antifer ensenadensis from southern Brazil, one of the largest forms that lived on this continent, using comparative morphology, geometric morphometrics, and encephalization quotients. The analyzed endocasts demonstrate that A. ensenadensis had a gyrencephalic brain, showing a prominent longitudinal sinus (=sagittal superior sinus), which is also observed in the large South American cervid Blastocerus dichotomus. The encephalization quotient is within the variation of extant cervids, suggesting maintenance of the pattern of encephalization from at least the late Pleistocene. Geometric morphometric analysis suggested a clear and linear allometric trend between brain endocast size and shape, and highlights A. ensenadensis as an extreme form within the analyzed cervids regarding brain morphology.     

A Survey Investigating the Infection of Fusarium langsethiae and Production of HT‐2 and T‐2 Mycotoxins in UK Oat Fields

Fusarium langsethiae is a toxigenic fungal species that has been reported in European small‐grain cereal crops such as oats, wheat and barley. Although its relative contribution to fusarium head blight (FHB) symptoms is not well understood, it is reported to contaminate these cereals with high levels of HT‐2 and T‐2 trichothecenes mycotoxins that are currently under consideration for legislation by the European Commission. Ten commercial oat fields in Shropshire and Staffordshire (two adjacent counties in the Midlands) in the UK were surveyed in the 2006/2007 growing season. Samples were taken from predetermined field locations at Zadoks growth stages 32/33, 69, 77‐85 and 90‐92 for F. langsethiae biomass and HT‐2 and T‐2 toxins quantification. The results from this study showed that oats can be heavily infected with F. langsethiae and have high concentrations of HT‐2 and T‐2 toxins with no apparent FHB symptoms. The regression of HT‐2 + T‐2 toxins on F. langsethiae DNA concentration was highly significant (P < 0.001, r² = 0.55). The results indicated that although F. langsethiae had no direct effect on crop yield, it may result in indirect economic losses where the grain can be rejected or downgraded as a result of intolerable levels of HT‐2 and T‐2 toxins, which are of human food and animal feed safety concern. The influence of cultural field practices on the infection and HT‐2 and T‐2 toxins accumulation in oats was not clear and warrants further studies to identify the sources of F. langsethiae inoculum and conditions favourable for infection and mycotoxin production.     

Diversity of cultivable rhizobacteria across tomato growing regions of Karnataka

Seven hundred and fifty-two rhizobacteria were isolated from 186 rhizosphere soil samples collected across tomato growing regions of Karnataka. Among them, 26% strains were Gram positive and other 74% were Gram negative and dominant being Bacillus and Pseudomonas. Sampling of different locations showed variation in species richness and diversity indices. Similarity matrix computed with Jaccard’s coefficient and principle coordinate analysis to correlate bacterial diversity revealed that rhizobacterial genera of Mysore, Mandya and Kolar soil samples were very closely related and rarefaction curve analysis indicated that these soil samples also harbored higher number of rhizobacteria which included all the genera studied. PGPR trait analysis revealed that most of the rhizobacteria were endowed with more than one beneficial trait which may act individually or simultaneously, and indole acetic acid production and phosphate solubilization are the two predominant traits exhibited by these rhizobacteria. Rhizobacterial isolates also showed a varied level of plant growth promotion traits and offered protection against fungal origin foliar and root pathogens. Among the nine regions studied, Mysore, Mandya and Kolar regions recorded higher percentage of promising PGPRs in comparison with other regions studied of Karnataka.     

The incidence, distribution and expression of Australian grapevine yellows, restricted growth and late season leaf curl diseases in selected Australian vineyards

Surveys were conducted in four Chardonnay vineyards for 3 to 6 years and one Shiraz vineyard for 3 years to determine the yearly percentage of grapevines affected by Australian grapevine yellows disease (AGYd), restricted growth disease (RGd) and late season leaf curl disease (LSLCd). In each of the Chardonnay vineyards in each year, all three diseases were characterised by remission of disease in some grapevines, recurrence of disease in other grapevines and new observations of disease in previously unaffected grapevines. The pattern of temporal incidence of each disease was different between vineyards for the survey period. Although Koch's postulates have not been fulfilled, phytoplasmas are considered to be the most likely cause of AGYd. While some grapevines exhibited a combination of AGYd and RGd or AGYd and LSLCd, both RGd and LSLCd can occur independently of AGYd. Statistical analyses using log-linear models also indicated that RGd and LSLCd were not always associated with AGYd. Thus, it is possible that phytoplasmas are not the cause of RGd or LSLCd and their association is coincidental. Expression of AGYd in Shiraz grapevines occurred later in the season compared to Chardonnay. Very little recurrence of AGYd was observed in the Shiraz grapevines indicating that the variety Shiraz responds differently to phytoplasma infections, assuming that AGYd in Shiraz is a phytoplasma caused disease. RGd and LSLCd were not observed on any grapevines in the Shiraz vineyard.     

In vivo control of Mycosphaerella pinodes on pea leaves by a crude bulb extract of Eucomis autumnalis

We previously reported on the in vitro antifungal activity of a crude whole plant extract from Eucomis autumnalis against seven economically important plant pathogenic fungi. A crude extract of the bulb showed similar in vitro mycelial growth inhibition of the same plant pathogenic fungi as well as that of an eighth fungus, Mycosphaerella pinodes, the cause of black spot or Ascochyta blight, in peas. Subsequently, fourth internode leaves were removed from 4 wk old pea plants, placed on moist filter paper in Petri dishes and inoculated with an M. pinodes spore suspension before and after treatment with the extract. The control of Ascochyta blight by different concentrations of the crude E. autumnalis extract was followed in vivo by leaf symptoms over a 6 day period at 20°C in a growth cabinet. The crude extract prevented M. pinodes spore infection of the leaves when the leaves were inoculated with spores both before or after treatment with the extract, confirming complete inhibition of spore germination. The crude E. autumnalis extract showed no phytotoxic reaction on the leaves even at the highest concentration applied.     

Comparative analysis of the lipopolysaccharides of a rough and a smooth strain of Pseudomonas syringae pv. phaseolicola

The lipopolysaccharides (LPS) of a rough (R) and a smooth (S) strain of Pseudomonas syringae pv. phaseolicola were analysed. The S-LPS revealed markedly more rhamnose and fucose, but less glucose, than the R-LPS. The presence of 3-O-methyl-rhamnose (acofriose) in the S-LPS was confirmed by cochromatography with authentic acofriose. SDS polyacrylamide gel electrophoresis of the S-LPS demonstrated a cluster of regularly spaced high molecular weight fractions, which was almost lacking in the R-LPS. The main fatty acids of the lipid A of both LPS species were 3-OH-10:0,3-OH-12:0,2-OH-12:0, and 12:0. Two N-linked diesters were demonstrated: 3-O(12:0)-12:0 and 3-O(2-OH-12:0)-12:0. S-LPS was subjected to mild hydrolysis and the degraded polysaccharide separated into three fractions by gel permeation chromatography on a Fractogel TSK HW-50 column. Fraction I, representing nearly only the O-specific side chain, consisted of rhamnose and fucose in a molar ratio of 4:1, with 4% of the rhamnose being 3-O-methylated (acofriose). Fraction II, representing mostly core material, was composed of glucose, rhamnose, heptose, glucosamine, galactosamine, alanine, and a still unidentified amino compound, in an approximate molar ratio of 3:1:1:1:1:1:1, and KDO. Fraction III consisted of released monomers and salts. The LPS was highly phosphorylated (3.28% phosphorus in the core fraction). The thus characterized composition of the LPS O-chain seems to be unique for the pathovar phaseolicola of P. syringae, although many similarities exist to other pathovars as well as to other bacterial species.Abbreviations LPS lipopolysacchairdes - GC/MS combined gas liquid chromatography-mass spectrometry - HVE high voltage electrophoresis - KDO 2-keto-3-deoxyoctonic acid - PAGE polyacrylamide gel electrophoresis - SDS sodium dodecylsulfate P.s. pv. phaseolicola is termed P. phaseolicola in the text     

Genetics of leaf blight resistance in wheat

Summary Studies on the genetics of leaf blight caused byAlternaria triticina using generation mean analysis revealed that additive components played a major role, but that dominance components also contributed significantly in controlling the variability for leaf blight resistance in wheat crosses. Furthermore, the additive x additive type of epistasis was predominant in the first three crosses, whereas in the fourth cross additive x dominance (j) and dominance x dominance (1) components of epistasis were most significant. Because of this it may be desirable to follow a simple recurrent selection scheme for higher tolerance, to isolate resistant plants from the segregating populations derived from crosses of parents of diverse origin following the pedigree method of breeding. CPAN-1887 was very tolerant to leaf blight in the present study and should be utilized in hybridization programs to develop leaf-blight-resistant varieties.     

Non‐pathogenic association of L‐form bacteria (pseudomonas syringae pv. phaseolicola) with bean plants (Phaseolus vulgaris L.) and its potential for biocontrol of halo blight disease

L‐forms of the halo blight pathogen, Pseudomonas syringae phaseolicola, were maintained in a medium which suppressed cell wall synthesis. These L‐forms, unlike revertants (walled forms derived from unstable L‐forms) and cell walled (parent) organisms, did not elicit a hypersensitive response in tobacco leaves. Association of L‐forms with Phaseolus vulgaris was established by seed imbibition in L‐form suspensions compared with appropriate control treatments (5% mannitol or heat‐killed cells). Seedling emergence and plant growth was not affected by L‐form imbibition. The association was detected by agglutination assays using polyclonal antibody. The L‐form association was localized to the lower shoot tissue and was progressively lost with age of plants. Plants with associated L‐forms had vigour and shoot weights equivalent to controls and showed no disease symptoms. The cell walled form could not be isolated from plants showing positive agglutination. On challenge with the pathogen, plants associated with L‐forms showed significantly less disease symptoms than controls. Stem extracts, from associated plants, were inhibitory to in vitro cultures of both L‐forms and parent forms of Ps. syr. phaseolicola. These results indicate that L‐form associations confer induced systemic resistance to bean plants and might be developed as novel biocontrol systems.     

Three further naphthoquinones produced by Fusarium solani

Three naphthoquinone pigments are described which were produced by Fusarium solani. They are 2,3-dihydro-5,8-dihydroxy-6-methoxy-2-hydroxymethyl-3-(2-hydroxypropyl)-1,4-naphthalenedione, 2,3-dihydro-5-hydroxy-4-hydroxymethyl-8-methoxy-naphtho[1,2-b]furan-6,9-dione and 5,8-dihydroxy-2-methoxy-6-hydroxymethyl-7-(2-hydroxypropyl)-1,4-naphthalenedione. One of these pigments was shown to be the precursor of the other two.