Further advances in orchid mycorrhizal research

Orchid mycorrhizas are mutualistic interactions between fungi and members of the Orchidaceae, the world’s largest plant family. The majority of the world’s orchids are photosynthetic, a small number of species are myco-heterotrophic throughout their lifetime, and recent research indicates a third mode (mixotrophy) whereby green orchids supplement their photosynthetically fixed carbon with carbon derived from their mycorrhizal fungus. Molecular identification studies of orchid-associated fungi indicate a wide range of fungi might be orchid mycobionts, show common fungal taxa across the globe and support the view that some orchids have specific fungal interactions. Confirmation of mycorrhizal status requires isolation of the fungi and restoration of functional mycorrhizas. New methods may now be used to store orchid-associated fungi and store and germinate seed, leading to more efficient culture of orchid species. However, many orchid mycorrhizas must be synthesised before conservation of these associations can be attempted in the field. Further gene expression studies of orchid mycorrhizas are needed to better understand the establishment and maintenance of the interaction. These data will add to efforts to conserve this diverse and valuable association

Nitrogen transport in the orchid mycorrhizal symbiosis - further evidence for a mutualistic association.

Mycorrhizas are symbioses integral to the health of plant-based ecosystems (Smith & Read, 2008). In a typical mycorrhizal association, fungi in, or on, plant roots pass soil-acquired inorganic nutrients and water to the plant host. In return, the host transfers excess photosynthate to the fungus

New Russulaceae species in south-east Queensland

Russula species are ectomycorrhizal basidiomycetes common throughout Australian woodlands. Molecular and morphological examination of Russula specimens from various sites in South-east Queensland has uncovered a number of phylogenetically diverse and potentially undescribed specimens. At this stage, most of these remain as individual specimens. However, several specimens have been grouped into project species. In this presentation, two potentially new species of Russula will be described. Both species are widespread on red to black clay soils in the Toowoomba region and appear to be phylogenetically related to each other. Project species 1 has a white stipe which developed a pink flush after collection and red to pink centrally depressed cap with white gills. The spores of this species were subglobose, white and ornamented with amyloid warts connected in short chains. The second species, project species 3, is macroscopically similar, differing with its larger size, purple-pink cap colour, and rougher cap texture. Its spores are globose to subglobose, white and ornamented with small amyloid warts connected in short chains. Continued molecular and morphological studies of the Russula species of South-east Queensland may uncover more novel Australian species

Derivation of dose/volume constraints for the anorectum from clinician and patient-reported outcomes in the CHHiP trial of radiotherapy fractionation.

BACKGROUND:The CHHiP trial randomised 3216 men with localised prostate cancer (1:1:1) to three radiotherapy fractionation schedules: 74Gy/37 fractions (f) over 7.4 weeks, 60Gy/20f/4 weeks and 57Gy/19f/3.8 weeks. Literature-based dose constraints were applied with arithmetic adjustment for the hypofractionated arms. This study aimed to derive anorectal dose constraints using prospectively-collected clinician-reported outcomes (CRO) and patient-reported outcomes (PRO) and to assess the added predictive value of spatial dose metrics. METHODS:A case-control study design was used, seven CRO and five PRO bowel symptoms were evaluated. Cases experienced a moderate or worse symptom 1-5 years post-radiotherapy, and did not have the symptom pre-radiotherapy. Controls did not experience the symptom at baseline, or between 1-5 years post-radiotherapy. The anorectum was re-contoured from the anal verge to the recto-sigmoid junction; dose/volume parameters were extracted. Univariate logistic regression, atlases of complication indices and bootstrapped receiver-operating-characteristic (ROC) analysis (1000 replicates, balanced outcomes) were used to derive dose constraints for the whole cohort (hypofractionated schedules were converted to 2Gy equivalent schedules using α/β=3Gy) and separate hypofractionated/conventional fractionation cohorts. Only areas under the curve (AUC) with 95% confidence interval lower limits >0.5 were considered statistically significant. Any constraint derived in <95-99% of bootstraps was excluded. RESULTS:Statistically significant dose constraints were derived for CRO, but not PRO. Intermediate to high doses were important for rectal bleeding whereas intermediate doses were important for increased bowel frequency, faecal incontinence and rectal pain. Spatial dose metrics did not improve prediction of CRO or PRO. A new panel of dose constraints for hypofractionated schedules to 60Gy or 57Gy are V20Gy<85%, V30Gy<57%, V40Gy<38%, V50Gy<22% and V60Gy<0.01%. CONCLUSIONS:Dose constraints differed between symptoms, indicating potentially different pathogenesis of radiation-induced side effects. Derived dose constraints were stricter than those used in CHHiP and may reduce bowel symptoms post-radiotherapy