The transcriptome of Populus in elevated CO reveals increased anthocyanin biosynthesis during delayed autumnal senescence.

*The delay in autumnal senescence that has occurred in recent decades has been linked to rising temperatures. Here, we suggest that increasing atmospheric CO2 may partly account for delayed autumnal senescence and for the first time, through transcriptome analysis, identify gene expression changes associated with this delay. *Using a plantation of Populus x euramericana grown in elevated [CO2] (e[CO2]) with free-air CO2 enrichment (FACE) technology, we investigated the molecular and biochemical basis of this response. A Populus cDNA microarray was used to identify genes representing multiple biochemical pathways influenced by e[CO2] during senescence. Gene expression changes were confirmed through real-time quantitative PCR, and leaf biochemical assays. *Pathways for secondary metabolism and glycolysis were significantly up-regulated by e[CO2] during senescence, in particular, those related to anthocyanin biosynthesis. Expressed sequence tags (ESTs) representing the two most significantly up-regulated transcripts in e[CO2], LDOX (leucoanthocyanidin dioxgenase) and DFR (dihydroflavonol reductase), gave (e[CO2]/ambient CO(2) (a[CO2])) expression ratios of 39.6 and 19.3, respectively. *We showed that in e[CO2] there was increased autumnal leaf sugar accumulation and up-regulation of genes determining anthocyanin biosynthesis which, we propose, prolongs leaf longevity during natural autumnal senescence.

Yield and spatial supply of bioenergy poplar and willow short-rotation coppice in the UK.

Limited information on likely supply and spatial yield of bioenergy crops exists for the UK. Here, productivities are reported of poplar (Populus spp.) and willow (Salix spp.) grown as short-rotation coppice (SRC), using data from a large 49-site yield trial network. A partial least-squares regression technique was used to upscale actual field trial observations across England and Wales. Spatial productivity was then assessed under different land-use scenarios. Mean modelled yields ranged between 4.9 and 10.7 oven-dry tonnes (odt) ha(-1) yr(-1). Yields were generally higher in willow than in poplar, reflecting the susceptibility of older poplar genotypes to rust and their tendency for single stem dominance. Replacing 10% of arable land, 20% of improved grassland and 100% of set-aside grassland in England and Wales with the three most productive genotypes would yield 13 Modt of biomass annually (supplying 7% of UK electricity production or 48% of UK combined heat and power (CHP) production). Results show existing SRC genotypes have the immediate potential to be an important component of a mixed portfolio of renewables and that, in future, as new and improved genotypes become available, higher yields could extend this potential further.

Biomedical surveillance of workers exposed to 4,4'-methylene-bis-(2-chloroaniline) (MBOCA) in Perth, Western Australia.

From 1984, a biomedical surveillance programme assessed the occupational exposure to 4, 4'-methylene-bis-(2-chloroaniline) (MBOCA) in seven factories which manufactured polyurethane polymers. Urinary MBOCA concentrations were used to assess absorption of MBOCA which is a scheduled carcinogen under the Poisons Act in Western Australia. The relevance and limitations of urinary MBOCA as a biological indicator of exposure to MBOCA, the use of spot urines based on creatinine concentrations in preference to 24 hour urine MBOCA estimations and urinary cytology are discussed. Preventive measures to reduce exposures to as low as reasonably achievable (ALARA principle) were implemented after a seminar held in April 1987 which was attended by representatives of the seven factories concerned. Statistically significant falls in mean 24-hour urinary MBOCA levels were observed in follow-up levels in the five factories for which 'post-seminar' levels were measured.