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Information about several papers discussed at the Forestry Workshop of the Plant and Animal Genome XV Conference, held in January 2007 in San Diego, California is presented. The event focused on the genomics and evolution of forest trees, including topics on adaptive polymorphisms, quantitative trait locus analysis and tree life style. It featured presentations by Emanuele De Paoli, Gail Taylor and Gerald Tuskan.

Information about several papers discussed at the polyploidy workshop of the Plant and Animal Genome XV Conference, held in January 2007 in San Diego, California is presented. The event covered several topics such as ancient polyploidy events in Glycine, expression evolution of duplicate genes, gene expression changes, hybridization barriers in Arabidopsis and tissue-specific and stress-induced expression patterns of duplicate genes in cotton and hybrid Populus.

Information about several papers discussed at the Fungal Genomics Workshop: Plant and Animal Genome XV Conference, held in January 2007 in San Diego, California is presented. The event focused on comparative genomics and global functional analyses in relation to fungi and oomycetes. It featured presentations by Sophien Kamoun, Gert Kema and Gary Payne.

Summary: Wildfires drastically impact the soil environment, altering the soil organic matter, forming pyrolyzed compounds, and markedly reducing the diversity of microorganisms. Pyrophilous fungi, especially the species from the orders Pezizales and Agaricales, are fire‐responsive fungal colonizers of post‐fire soil that have historically been found fruiting on burned soil and thus may encode mechanisms of processing these compounds in their genomes.Pyrophilous fungi are diverse. In this work, we explored this diversity and sequenced six new genomes of pyrophilous Pezizales fungi isolated after the 2013 Rim Fire near Yosemite Park in California, USA: Pyronema domesticum, Pyronema omphalodes, Tricharina praecox, Geopyxis carbonaria, Morchella snyderi, and Peziza echinospora.A comparative genomics analysis revealed the enrichment of gene families involved in responses to stress and the degradation of pyrolyzed organic matter. In addition, we found that both protein sequence lengths and G + C content in the third base of codons (GC3) in pyrophilous fungi fall between those in mesophilic/nonpyrophilous and thermophilic fungi.A comparative transcriptome analysis of P. domesticum under two conditions – growing on charcoal, and during sexual development – identified modules of genes that are co‐expressed in the charcoal and light‐induced sexual development conditions. In addition, environmental sensors such as transcription factors STE12, LreA, LreB, VosA, and EsdC were upregulated in the charcoal condition.Taken together, these results highlight genomic adaptations of pyrophilous fungi and indicate a potential connection between charcoal tolerance and fruiting body formation in P. domesticum. [ABSTRACT FROM AUTHOR]

Information on several papers discussed at the Mediterranean Ecosystems (MEDECOS) XII conference on fire as an evolutionary pressure shaping plant traits held in Los Angeles, California on September 2011 is presented. Topics include ecological science, role of fire in biome distribution, and micro-evolutionary approach to show the natural selection driven by fire. The conference features several presenters including William Bond, Susana Gómez-González, and Juli G. Pausas.

Summary: Xylem anatomy and function have large implications for plant growth as well as survival during drought, but the impact of nutrient limitation on xylem is not fully understood. This study examines the pygmy forest in California, a plant community that experiences negligible water stress but is severely stunted by low‐nutrient and acidic soil, to investigate how nutrient limitation affects xylem function.Thirteen key anatomical and hydraulic traits of stems of four species were compared between pygmy forest plants and nearby conspecifics growing on richer soil.Resistance to cavitation (P50), a critical trait for predicting survival during drought, had highly species‐specific responses: in one species, pygmy plants had a 26% decrease in cavitation resistance compared to higher‐nutrient conspecifics, while in another species, pygmy plants had a 56% increase in cavitation resistance. Other traits responded to nutrient limitation more consistently: pygmy plants had smaller xylem conduits and higher leaf‐specific conductivity (KL) than conspecific controls.Edaphic stress, even in the absence of water stress, altered xylem structure and thus had substantial impacts on water transport. Importantly, nutrient limitation shifted cavitation resistance in a species‐specific and unpredictable manner; this finding has implications for the assessment of cavitation resistance in other natural systems. [ABSTRACT FROM AUTHOR]

Summary: In his foundational list of 'ideal weed' characteristics, Baker (1965) proposed that weedy plants maximize reproductive output under high resource availability. Since then, the idea that invasive plant species are more responsive to fluctuating resources compared with native or noninvasive species has gained considerable traction, although few studies extend this hypothesis to include reproductive output. We revisit Baker's hypothesis in the context of invasion and drought in California grasslands, exploring whether invasives show greater growth and reproductive responses to water availability compared with the native wildflowers they displace.In an outdoor potted study, we grew eight native and eight invasive species of annuals commonly found in southern California grasslands to reproductive maturity under both well‐watered and drought conditions.While drought negatively impacted plant performance overall, invasives showed more negative responses for growth and reproductive traits. Invasives also grew larger than native species, especially under well‐watered conditions, and produced seed with higher rates of germination.Invasives may be more negatively impacted by drought compared with natives, but they are also able to capitalize on high resource conditions and greatly increase reproductive output. Such opportunistic responses exhibited by invasives might explain previously observed fluctuations in their abundance under variable precipitation. [ABSTRACT FROM AUTHOR]

Summary [ABSTRACT FROM AUTHOR]

Information about the topics discussed at the 25th Fungal Genetics Conference held in Pacific Grove, California is presented. The event talked about fungal class Dothideomycetes, the development on comparative analysis of this class and the class's interaction with their host plants. It featured several fungal geneticists, including Shaobin Zhong, Salim Bourras and Sarrah Ben M'Barek.

• Studies examining plant distribution patterns across environmental gradients have generally focused on perennial-dominated systems, and we know relatively little about the processes structuring annual communities. Here, the ecological factors determining local distribution patterns of five dominant annual species distributed across micro-topographic gradients in ephemeral California wetlands are examined. • Over two growing seasons in three vernal pools, patterns of inundation and above-ground biomass were characterized across the microtopographic gradient, population boundaries for five dominant species were documented and a reciprocal transplant experiment and neighbor removal treatment were conducted to test the relative effects of within-pool elevation, competition and seed dispersal on plant performance. • Despite large differences in inundation time between growing seasons, above-ground biomass and the elevation of population boundaries remained consistent. The predicted ‘optimal’ depth for each species shifted between years, but competition and recruitment limitation restricted species’ abilities to track these conditions. • The distributions of the focal taxa are primarily driven by differential responses to environmental conditions associated with different microtopographic positions along pool inundation gradients, and are reinforced by competition and dispersal constraints. The relative importance of competition, other environmental factors and dispersal patterns appear to contrast with results obtained in systems dominated by perennial plants. [ABSTRACT FROM AUTHOR]

• Plant adaptations to the environment are limited, and therefore plants in similar environments may display similar functional and physiological traits, a pattern termed functional convergence. Evidence was examined for functional convergence among 28 evergreen woody shrubs from three plant communities of the semi-arid winter rainfall region of southern California. • Both leaf and water relations traits were examined, including seasonal stomatal conductance ( gs), specific leaf area (SLA), leaf specific conductivity ( Kl), seasonal water potential (Ψw), stem cavitation resistance (Ψ50), and xylem density. • Species display community-specific suites of xylem and leaf traits consistent with different patterns of water use among communities, with coastal sage scrub species utilizing shallow pulses of water, Mojave Desert scrub species relying on deeper water reserves, and chaparral species utilizing both shallow and deep moisture reserves. Communities displayed similar degrees of water stress, with a community-level minimum Ψw (Ψwmin) of c. −4.6 Mpa, similar to other arid communities. Pooled across sites, there was a strong correlation between Ψwmin and xylem density, suggesting that these traits are broadly related and predictive of one another. • This comparative community physiology approach may be useful in testing hypotheses of functional convergence across structurally similar semi-arid communities. [ABSTRACT FROM AUTHOR]

• Plant host species is considered an important factor influencing ectomycorrhizal (EM) communities. To gain insights into the role of host species in structuring EM communities, EM communities on sympatric oak ( Quercus) species were compared in the Sierra Nevada foothills of California. • Using molecular methods (polymerase chain reaction, cloning, restriction fragment length polymorphism and DNA sequencing), EM fungi on roots of deciduous Quercus douglasii and evergreen Quercus wislizeni trees were identified from 64 soil cores. • The total EM species richness was 140, of which 40 taxa were detected on both oak hosts. Greater diversity and frequency of EM fungi with epigeous fruiting habit were found on Q. wislizeni, while taxa in the Ascomycota were more frequent and diverse on Q. douglasii. • Using ordination, it was determined that both soil extractable phosphorus and oak host species explained a significant proportion of the variation in EM species distribution. These results indicate that plant host species can be an important factor influencing EM fungal community composition, even within congeneric trees. [ABSTRACT FROM AUTHOR]

The article discusses the highlights of two symposia on functional genomics and ecology held at the Ecological Society of America 92nd Annual Meeting in San Jose, California, in August 2007. One symposium focused on linking physiological ecology, evolutionary biology and functional genomics for understanding biotic responses to a changing environment. A second symposium addressed the mechanistic underpinnings of ecological processes with a special emphasis on scaling relationships from genes to ecosystems.

The article discusses the highlights of a session on meta-analysis held at the Ecological Society of America 92nd Annual Meeting in San Jose, California, in August 2007. Researchers discussed the use of meta-analysis in the field ecology during the session. They presented some techniques for ecological meta-analysis that have been borrowed from other disciplines.

The article discusses the highlights of a session on global climate change at the Ecological Society of America 92nd Annual Meeting held in San Jose, California, in August 2007. Researchers summarized the findings of studies on the roles of global warming in a variety of ecosystems. They indicated that determining the nature and tempo of successional changes in ecosystems in response to warming remains a key challenge.

The article discusses the highlights of mycorrhizal ecology and related sessions at the Ecological Society of America 92nd Annual Meeting held in San Jose, California, in August 2007. Researchers reported some of their work on mycorrhiza at the meeting. Shannon Schechter presented a cloning and sequencing approach to compare arbuscular mycorrhizal fungi. Researchers were also interested in using tools developed by ecologists and testing ecological theories developed for other organisms on fungi.

• Quantification of the fate of carbon (C) used by plant metabolism is necessary to improve predictions of terrestrial ecosystem respiration and its sources. • Here, a dual isotope (13C and 14C) pulse-label was used to determine the allocation of new C to different respiratory pathways in the early and late growing seasons for two plant functional types, perennial grasses and shrubs, in the Owens Valley, CA, USA. • Allocation differences between plant types exceeded seasonal allocation variation. Grasses respired 71 and 64% and shrubs respired 22 and 17% of the label below-ground in the early and late growing seasons, respectively. Across seasons and plant types, ~48–61% of the label recovered was respired in 24 h, ~68–84% in 6 d, and ~16–33% in 6–36 d after labeling. • Three C pools were identified for plant metabolism: a fast pool with mean residence times (MRTs) of ~0.5 and ~1 d below- and above-ground, respectively; an intermediate pool with MRTs of 19.9 and 18.9 d; and a storage pool detected in new leaf early growing season respiration > 9 months after assimilation. Differences in allocation to fast vs intermediate C pools resulted in the mean age of C respired by shrubs being shorter (3.8–4.5 d) than that of the grasses (4.8–8.2 d). [ABSTRACT FROM AUTHOR]

• Stable isotope abundance analyses recently revealed that some European green orchids and pyroloids (Ericaceae) are partially myco-heterotrophic, exploiting mycorrhizal fungi for organic carbon and nitrogen. Here we investigate related species to assess their nutritional mode across various forest and climate types in Germany and California. • C- and N-isotope signatures of five green pyroloids, three green orchids and several obligate myco-heterotrophic species (including the putatively fully myco-heterotrophic Pyrola aphylla) were analysed to quantify the green plants’ nutrient gain from their fungal partners and to investigate the constancy of enrichment in 13C and 15N of fully myco-heterotrophic plants from diverse taxa and locations relative to neighbouring autotrophic plants. • All green pyroloid and one orchid species showed significant 15N enrichment, confirming incorporation of fungi-derived N compounds while heterotrophic C gain was detected only under low irradiance in Orthilia secunda. Pyrola aphylla had an isotope signature equivalent to those of fully myco-heterotrophic plants. • It is demonstrated that primarily N gain from mycorrhizal fungi occurred in all taxonomic groups investigated across a wide range of geographical and ecological contexts. The 13C and 15N enrichment of obligate myco-heterotrophic plants relative to accompanying autotrophic plants turned out as a fairly constant parameter. [ABSTRACT FROM AUTHOR]

Information about the recent advances in small ribonucleic acids (RNA) and epigenetics within the plant science field, discussed at the 24th Symposium in Plant Biology in Riverside, California in January 2007, is presented. It discusses several works about RNA that were presented at the meeting and summarizes the current status of the field in plants. It also points out other issues related to the topic that will be explored in the future.

• Our primary goal was to determine whether detection of Rhizopogon internal transcribed spacer (ITS) groups is affected by the pine species used in seedling bioassays. Our secondary goal was to investigate composition of Rhizopogon spore banks in the Eastern Sierra Nevada of California, a previously unsampled region. • We used seedlings of Pinus contorta, Pinus jeffreyi, Pinus lambertiana, and Pinus muricata as bioassay plants and identified the Rhizopogon retrieved by internal transcribed spacer (ITS) sequence analysis. • We found that each of the pine species retrieved all of the abundant Rhizopogon ITS groups, but there were significant differences among pines in the richness of Rhizopogon ITS groups recovered. Pinus muricata recovered all ITS groups found in this study and was significantly better than P. lambertiana. Rhizopogon communities from the five sampled sites contained six to eight ITS groups per site, with two unique sequence groups and a higher abundance of the Rhizopogon ellenae and Rhizopogon arctostaphyli groups than at previously sampled sites. • These results show high cross-receptivity between Rhizopogon and pine species, and regional patterns in spore bank composition. [ABSTRACT FROM AUTHOR]

The ecology of a recently evolved species, Mimulus cupriphilus, was compared with its presumed progenitor, M. guttatus. Both species live sympatrically as annuals on two small copper mines in Calaveras county, California, USA. There are almost no other species present in the areas where Mimulus dominates. The production of seed by the two species was compared. The relationship between capsule number and plant height differs, with M. cupriphilus having the steeper slope, so that at any particular height it produces more capsules. Mean seed number per capsule, and the relationship between seed number and size of plant, also varies between the two species. M. cupriphilus is normally self-fertilizing, and thus has a higher probability that a capsule will be fertilized than M. guttatus, which relies more on fertilization by insects. The various parameters can be combined to produce a predicted relationship between size of plant and seed production. When plants are small, M. cupriphilus will produce more seeds, but at heights greater than about 9 cm M. guttatus will be fitter. The overall resource allocation pattern also reveals that M. cupriphilus devotes a greater proportion of its dry weight to seed and capsule production. These results show that in the habitat where the two species co-exist, arid deserted copper mines, the derived species is better adapted. [ABSTRACT FROM AUTHOR]