Study of the competition between Colletotrichum godetiae and C. nymphaeae, two pathogenic species in olive

Olive anthracnose, a critical olive fruit disease that adversely impacts oil quality, is caused by Colletotrichum species. A dominant Colletotrichum species and several secondary species have been identified in each olive-growing region. This study surveys the interspecific competition between C. godetiae, dominant in Spain, and C. nymphaeae, prevalent in Portugal, to shed light on the cause of this disparity. When Petri-dishes of Potato Dextrose Agar (PDA) and diluted PDA were co-inoculated with spore mixes produced by both species, C. godetiae displaced C. nymphaeae, even if the percentage of spores in the initial spore mix inoculation was just 5 and 95%, respectively. The C. godetiae and C. nymphaeae species showed similar fruit virulence in separate inoculations in both cultivars, the Portuguese cv. Galega Vulgar and the Spanish cv. Hojiblanca, and no cultivar specialization was observed. However, when olive fruits were co-inoculated, the C. godetiae species showed a higher competitive ability and partially displaced the C. nymphaeae species. Furthermore, both Colletotrichum species showed a similar leaf survival rate. Lastly, C. godetiae was more resistant to metallic copper than C. nymphaeae. The work developed here allows a deeper understanding of the competition between C. godetiae and C. nymphaeae, which could lead to developing strategies for more efficient disease risk assessment.

First Report of Root Rot Caused by Pythium spiculum Affecting Cork Oaks at Doñana Biological Reserve in Spain

Cork oaks (Quercus suber L.) are key tree species at Doñana Biological Reserve (DBR), Huelva, Spain. Sampling was conducted on a total of 13 trees exhibiting symptoms of decline (foliar wilting and defoliation, branch dieback, and root necrosis). In 2008. Phytophthora cinnamomi was isolated from feeder roots of one tree and Pythium spiculum from two additional oaks. In 2011, both pathogens were isolated from six oaks, only P. cinnamomi from three oaks, and only Py. spiculum from one oak. This expansion was associated with high winter rainfall levels since 2009 that led to long periods of soil flooding. While P. cinnamomi is well known to cause a root disease on Q. suber (2), P. spiculum is a newly described species isolated from Quercus, Vitis, Prunus, Castanea, and Celtis species, but its pathogenicity was demonstrated only on Q. ilex (syn. Q. rotundifolia) (1). Pathogenicity tests were conducted on 4-year-old Q. suber plants. Inocula consisted of two isolates of Py. spiculum from DBR (DO8 and DO36 from Q. suber). For comparison with these, three isolates previously tested on Q. ilex (1) were included: two isolates of Py. spiculum, PA54 (from Q. suber) and PE156 (from Q. ilex); and one isolate of P. cinnamomi, PE90 (from Q. ilex). All these isolates came from the Andalucía region, stored at the oomycete collection of the University of Córdoba, and showed a 99 to 100% homology with their expected ITS sequences in GenBank (DQ196131 for Py. spiculum and AY943301 for P. cinnamomi). Inoculum was prepared by shaking and mixing propagule-bearing mycelium produced in carrot broth petri dishes (20°C, 4 weeks) in sterile water, to produce a concentration of 3 × 10⁴ oospores × ml^-1 (Py. spiculum) or 3 × 10⁴ chlamydospores × ml^-1 (P. cinnamomi). One hundred milliliters of inoculum was applied to each root (1). There were 10 inoculated plants per isolate and 10 non-inoculated control plants. All plants were waterlogged 2 days per week to favor root infection and maintained in an acclimatised greenhouse (12-28°C). Three months later, the inoculated plants showed symptoms of root necrosis that resulted in foliar wilting followed occasionally by defoliation. Control plants did not develop foliar symptoms nor root necrosis. Root damage severity assessed on a 0 to 4 scale (3) exhibited significant differences (P < 0.05) in relation to the control plants for all the isolates tested, with isolate PE90 (P. cinnamomi) and isolates PA54, DO8, and DO36 (P. spiculum) all averaging a root necrosis value of 2.5. Isolate PE156 of P. spiculum produced values of root necrosis (1.6 in average) significantly lower (P < 0.05) than the rest. This isolate belongs to the low virulence group of P. spiculum described on Q. ilex (1). The inoculated oomycete was always reisolated from necrotic roots and never from roots of control plants. To the best of our knowledge, this is the first report of P. spiculum as the cause of root rot of Q. suber. References: (1) Romero et al. J. Phytopathol. 155:289, 2007. (2) Sánchez et al. For. Pathol. 32:5, 2002. (3) Sánchez et al. For. Pathol. 35:115, 2005.

Use of infliximab in pediatric patients with inflammatory bowel disease

BACKGROUND

The concentration of tumor necrosis factor, a proinflammatory cytokine, is increased in the gastrointestinal mucosa of patents with active Crohn's disease (CD) and ulcerative colitis (UC). Neutralization of tumor necrosis factor decreases the mucosal inflammatory response of adults with CD. Little information is available on the use of monoclonal antibody to tumor necrosis factor (infliximab) in children and adolescents with CD or UC.

OBJECTIVE

To evaluate the clinical response and side effects of patients to infliximab.

METHODS

A retrospective review of data regarding 18 pediatric and adolescent patients with active CD (n = 15) and UC (n = 3) poorly controlled with conventional therapy. All patients received one to six intravenous infusions of infliximab 5 mg/kg, while receiving their usual medications.

RESULTS

All patients experienced clinical improvement, including decrease in the frequency of stooling and resolution of extraintestinal symptoms such as arthropathy, malaise, and skin manifestations after treatment with infliximab. All but one patient had a documented decrease in the erythrocyte sedimentation rate. Prednisone dosage was tapered in all but two patients, and discontinued in seven patients. Intravenous infusion of infliximab was well tolerated. One patient developed a rash several days after the infusion. A patient who received six infliximab infusions developed recurrent Staphylococcus aureus infections, as well as septic arthritis and chronic osteomyelitis during the follow-up period, raising the issue of the long-term safety of infliximab.

CONCLUSIONS

Treatment of our patients with refractory CD and UC with infliximab was associated with remarkable clinical improvement. Although the drug may have an important role in their management, further assessment of long-term safety and efficacy is needed.

Comparison of AC electronic monitoring and field data for estimating tolerance to Empoasca kraemeri (Homoptera: Cicadellidae) in common bean genotypes

Two methods for estimating the tolerance of common bean genotypes to Empoasca kraemeri Ross & Moore were compared, using a yield trial carried out at Centro Internacional de Agricultura Tropical (CIAT), Cali, Colombia, versus stylet penetration tactics measured by AC electronic feeding monitors. A stylet penetration index was devised based on principal component scores of three penetration tactics identified (pulsing laceration, cell rupturing, and lancing sap ingestion), combined with knowledge of the hopperburn symptoms caused by each tactic. Tolerant genotypes, as classified by the CIAT yield index, showed significantly more unprotected yield and lower hopperburn scores than the susceptible control. They also induced performance of less pulsing laceration (the tactic considered most damaging to the plant), and more of the other two, mitigating tactics, especially cell rupturing. When index values were calculated for each genotype, stylet penetration index values matched those of the yield index for three out of five genotypes: two EMP-coded tolerant lines ('EMP 385' and 'EMP 392') and the susceptible control 'BAT 41'. Thus, for these three genotypes, all subsequent hoppereburn symptoms are predictable by the type of feeding behavior performed on them. 'Porrillo Sintético' and 'EMP 84', considered borderline genotypes by the yield index, were overestimated and underestimated respectively, by the stylet penetration index. We postulate that, for these two genotypes, plant physiological responses to feeding (either compensatory or heightened sensitivity, respectively) synergize with type of feeding performed to generate the overall hopperburn condition. This multivariate analysis of electronic monitoring data was successfully used to devise an index of resistance. The implications of using the stylet penetration index and the advantages of using electronic monitoring in a bean-breeding program are discussed.

Leptospira fainei sp. nov., isolated from pigs in Australia

Pathogenic leptospires can be causative agents of reproductive problems in pigs. Cultures of uteri and kidneys from two pigs herds in New South Wales and Victoria (Australia) yielded five strains identified as Leptospira on morphological and cultural grounds. Phenotypic characteristics (growth at 13 and 30 degrees C, growth in the presence of 8-azaguanine) were intermediate between those of pathogenic and saprophytic leptospires. No cross-agglutination was observed with reference antisera representing the 24 pathogenic serogroups and the main saprophytic ones. Antiserum against one of the strains did not agglutinate reference stains representative of any serogroup. This provided evidence of a new serovar, designated hurstbridge. Genomic characterization of the five strains was achieved using five molecular approaches. Mapped restriction site polymorphisms in the rrs (16S rRNA) gene were not related to those of any reference strains. Arbitrarily primed PCR fingerprints suggested clonality of the five strains. The strains all showed an identical and unique PFGE profile. PCR, using primers specific for the rrs gene of pathologic leptospires, amplified corresponding sequences from the strains. DNA-DNA hybridization (and reciprocal experiments) using the S1 nucleas/TCA method was performed between one of the strains and the reference strains of Leptospira species. The homology ranged from 0 to 36% (the latter being was Leptospira inadai) thus satisfying the criterion of a new species, Leptospira fainei (type strain BUT 6T). Phylogenetic analysis of 16S rRNA sequence showed that L. fainei and L. inadai formed a clade separate from the previously recognized 'saprophyte' and 'pathogen' clades.