Improving sugarcane for biofuel: engineering for an even better feedstock

Sugarcane is a proven biofuel feedstock and accounts for about 40% of the biofuel production worldwide. It has a more favorable energy input/output ratio than that of corn, the other major biofuel feedstock. The rich resource of genetic diversity and the plasticity of autopolyploid genomes offer a wealth of opportunities for the application of genomics and technologies to address fundamental questions in sugarcane towards maximizing biomass production. In a workshop on sugarcane engineering held at Rutgers University, we identified research areas and emerging technologies that could have significant impact on sugarcane improvement. Traditional plant physiological studies and standardized phenotypic characterization of sugarcane are essential for dissecting the developmental processes and patterns of gene expression in this complex polyploid species. Breeder friendly DNA markers associated with target traits will enhance selection efficiency and shorten the long breeding cycles. Integration of cold tolerance from Saccharum spontaneum and Miscanthus has the potential to expand the geographical range of sugarcane production from tropical and subtropical regions to temperate zones. The Flex-stock and mix-stock concepts could be solutions for sustaining local biorefineries where no single biofuel feedstock could provide consistent year-round supplies. The ever increasing capacities of genomics and biotechnologies pave the way for fully exploring these potentials to optimize sugarcane for biofuel production.     

Distinguishing the effects of light and temperature variations on the growth, development, multiplication potential and ex vitro survival rates of in vitro cassava

Dissemination of cassava tissue culture plantlets is difficult in the arid tropics due to low eux vitro survival rates. Increased in vitro light intensity has been reported to induce high ex vitro survival rates. The results from earlier experiments suggested that it would be worthwhile to analyse the separate effects of in vitro light and of temperature on the in vitro growth pattern as well as differentiate its relation to ex vitro survival. Accordingly, analysis of a range of in vitro light intensities from 0 to 369 μmol^?1 m^?2 photosynthetic photon flux density (PPFD) was conducted both with and without fans to control the heat. Temperature proved stable at low PPFD levels but increased above 204 μmol s^?1 m^?2 when no fans were used. Increased PPFD levels induced larger fresh and dry masses as well as stem thickness. PPFD levels affected the developmental index (senescent leaf numbers) in vitro when it rose above 204 μmol s^?1 m^?2 PPFD. Raised temperature ranges increased the multiplication index (node numbers) in vitro and ex vitro. It increased root number and leaf development (lobe anatomy). As in vitro temperatures of up to 40°C improve multiplication rates and PPFD levels above 101 μmol s^?1 m^?2 were detrimental for ex vitro survival (as low as 60%), it is suggested that simpler and less costly laboratories with low light levels and a wide range of temperature tolerance could be successfully established in the tropics for in vitro cleaning and rapidly multiplying crops like cassava.     

Euglenoid morphospecies replacement along a hydraulic gradient of the Lower Paraná Basin (Argentina)

1. This study deals with the distribution of euglenoid morphospecies along the length of the Lower Paraná River floodplain. Six sites located in the Paraná River, Estevez stream and Montiel shallow lake were surveyed monthly from May 1995 to April 1996. 2. Eighty‐eight infrageneric taxa were registered though the total density percentage of euglenoids seldom exceeded 15% of total phytoplankton. The increasing species richness towards the lake is mostly the result of a high contribution of species of Trachelomonas and naked infrageneric taxa of Euglena, Lepocinclis and Phacus, while the distribution of Strombomonas species along the transect is fairly constant. 3. The richness of euglenoid morphospecies follows a pattern opposite to that found for the entire phytoplankton community. The distribution of euglenoids differs among the three habitats defined in this study: river, stream, shallow lake. These differences depend on the hydraulic condition of each habitat, as revealed by canonical correspondence analysis. 4. The degree of association with each type of aquatic habitat varied among the species and differed between water phases. Strombomonas fluviatilis was equally constant along the length of the ecotone, while S. girardiana and S. scabra were particularly associated with the Paraná River and P. longicauda, L. truncata, T. hispida and T. similis with the lake. 5. The flood pulse establishes a clear pattern both in species richness and abundance of euglenoids. The number of species recorded during high water was more than twice that recorded during low water.     

Evidence for speciational change in the evolution of ratites (Aves: Palaeognathae)

To perform a comparative analysis of character associations framed in a phylogenetic context (e.g. independent contrasts), a model of character evolution must be assumed. According to phyletic gradualism, morphological change accumulates gradually over time within lineages, and speciation events do not have a major role. Under speciational models, morphological change is assumed to occur during or just after cladogenesis in both daughter species, and the resulting morphologies do not change over long periods of time (stasis), until the next cladogenetic event. A novel method is presented for comparing these models of character evolution that uses permutational multiple phylogenetic regressions. The addition of divergence times to well-corroborated phylogenetic trees and the utilization of the method developed in this paper allows the estimation of relative frequency of gradual change and speciational change from living organisms. This method is applied to a dataset from ratites with the conclusion that, for a range of morphological features, change tends to have been speciational rather than gradual.  © 2003 The Linnean Society of London, Biological Journal of the Linnean Society , 2003, 80 , 99–106.     

Relationships between bone growth rate, body mass and resting metabolic rate in growing amniotes: a phylogenetic approach

We explored the factors that explain the variation in resting metabolic rates (RMR) in growing amniotes by using the phylogenetic comparative method. For this, we measured raw RMR (mL O₂ h⁻¹), body mass, body mass growth rate, and periosteal bone growth rate in a sample of 44 growing individuals belonging to 13 species of amniotes. We performed variation partitioning analyses, which showed that phylogeny explains a significant fraction of the variation of mass-specific RMR (mL O₂ h⁻¹ g⁻¹), and that the cost of growth is much higher than the cost of maintenance. Moreover, we tested the hypothesis of the independence of energy allocation, and found that maintenance metabolism and growth rates are not significantly related. Finally, we calculated the statistical parameters of the relationship between geometry-corrected RMR (mL O₂ h⁻¹ g^−0.67) and bone growth rate. This relationship could potentially be used in palaeobiology to infer RMR from bone tissue samples of fossil species by assuming Amprino's rule (according to which bone tissue types reflect bone growth rates). These estimates would be especially interesting for Mesozoic non-avian theropod dinosaurs and Permian and Triassic therapsids to investigate, respectively, the origin of avian and mammalian endothermy.  © 2007 The Linnean Society of London, Biological Journal of the Linnean Society , 2007, 92 , 63–76.     

The Deschampsia cespitosa complex (Poaceae: Aveneae) with special reference to Russia

The Deschampsia cespitosa complex in Russia is revised. Related taxa common to Russia and adjacent regions (i.e. northern Europe, Arctic America and Japan) are also considered. Deschampsia cespitosa s.l. is characterized by open to less commonly rather contracted panicles, spikelets (1) 2 (3)-flowered, 4-toothed lemmas with the lateral teeth larger, and awns straight or bent, inserted from the base to the top of the lemmas. Due to extensive overlapping in diagnostic characters, it is not possible to accept the specific status for D. borealis (Traut.) Roshev., D. brevifolia R.Br., D. macrothyrsa Tatew. et Ohwi and D. obensis Roshev; instead, they are treated as subspecies of D. cespitosa (L.) Beauv. Morphological differences are insufficient for a clear differentiation among subspecies, and geographical distributions also need to be considered. A total of 14 subspecies is accepted. Observations on ecology, problems of specific and subspecific delimitation, a distribution map, and considerations of evolution of the complex are provided. One new combination is made, Deschampsia cespitosa ssp. sukatschewii (Popl.) Chiapella & Prob.  © 2003 The Linnean Society of London, Botanical Journal of the Linnean Society , 2003, 142 , 213–228.     

Ecology shapes metabolic and life history scalings in termites

1. Metabolic rate (B) is a fundamental property of organisms, and scales with body mass (M) as B = αM^β. There has been much debate on whether scaling parameters should be viewed as constants or variables. However, there is increasing evidence that ecological differentiation can affect both α and β. 2. In colonial organisms such as social insects, individual metabolism is integrated at the colony level. Theory and data suggest that whole‐colony metabolism partly reflects individual‐level metabolic and life‐history scalings, but whether these have been affected by ecological diversification is little known. 3. Here, this issue was addressed using termites. Data from the literature were assembled to assess the interspecific scalings of individual metabolic rate with individual mass, and of individual mass with colony mass. Concurrently, it was tested whether such scalings were affected by two key ecological traits: lifestyle and diet. 4. Individual‐level metabolic scaling was affected by diet, with β = 1.02 in wood feeders and 0.60 in soil feeders. However, there was no difference in α. Further, individual mass scaled to the 0.25 power with colony mass, but forager species had larger colonies and smaller individuals relative to wood‐dwelling, sedentary ones, thus producing a grade shift. 5. Our results show that ecological diversification has affected fundamental metabolic and life‐history scalings in termites. Thus, theory on the energetics and evolution of colonial life should account for this variability.     

Vertical transmission in feather mites: insights into its adaptive value

1. The consequences of symbiont transmission strategies are better understood than their adaptive causes. 2. Feather mites are permanent ectosymbionts of birds assumed to be transmitted mainly vertically from parents to offspring. The transmission of Proctophyllodes doleophyes Gaud (Astigmata, Proctophyllodidae) was studied in two European populations of pied flycatchers, Ficedula hypoleuca Pallas (Passeriformes, Muscicapidae). 3. The vertical transmission of this mite species is demonstrated here with an acaricide experiment. This study also compared (for two distant populations during 4 years) patterns in reductions in mite intensity in adult birds, from egg incubation to chick‐rearing periods, with the predictions of three hypotheses on how host survival prospects and mite intraspecific competition might drive feather mites' transmission strategy. 4. The results are in agreement with previous studies and show that feather mites transmit massively from parents to chicks. 5. The magnitude of the transmission was closer to that predicted by the hypothesis based on intraspecific competition, while a bet‐hedging strategy is also partially supported.     

A new endemic species of Arubis L. (Cruciferae) from central Portugal

A new species, Arubis beirunu P. Silveira, Paiva & N. Marcos, from central Portugal is described and illustrated. A list of diagnostic differences between Arabis beirana and the closely related species A. sadina and A. stenocarpa is provided