Spatial variability in herbaceous plant phenology is mostly explained by variability in temperature but also by photoperiod and functional traits.

Whereas temporal variability of plant phenology in response to climate change has already been well studied, the spatial variability of phenology is not well understood. Given that phenological shifts may affect biotic interactions, there is a need to investigate how the variability in environmental factors relates to the spatial variability in herbaceous species' phenology by at the same time considering their functional traits to predict their general and species-specific responses to future climate change. In this project, we analysed phenology records of 148 herbaceous species, which were observed for a single year by the PhenObs network in 15 botanical gardens. For each species, we characterised the spatial variability in six different phenological stages across gardens. We used boosted regression trees to link these variabilities in phenology to the variability in environmental parameters (temperature, latitude and local habitat conditions) as well as species traits (seed mass, vegetative height, specific leaf area and temporal niche) hypothesised to be related to phenology variability. We found that spatial variability in the phenology of herbaceous species was mainly driven by the variability in temperature but also photoperiod was an important driving factor for some phenological stages. In addition, we found that early-flowering and less competitive species characterised by small specific leaf area and vegetative height were more variable in their phenology. Our findings contribute to the field of phenology by showing that besides temperature, photoperiod and functional traits are important to be included when spatial variability of herbaceous species is investigated.

Functional traits influence patterns in vegetative and reproductive plant phenology - a multi-botanical garden study.

Phenology has emerged as key indicator of the biological impacts of climate change, yet the role of functional traits constraining variation in herbaceous species' phenology has received little attention. Botanical gardens are ideal places in which to investigate large numbers of species growing under common climate conditions. We ask whether interspecific variation in plant phenology is influenced by differences in functional traits. We recorded onset, end, duration and intensity of initial growth, leafing out, leaf senescence, flowering and fruiting for 212 species across five botanical gardens in Germany. We measured functional traits, including plant height, absolute and specific leaf area, leaf dry matter content, leaf carbon and nitrogen content and seed mass and accounted for species' relatedness. Closely related species showed greater similarities in timing of phenological events than expected by chance, but species' traits had a high degree of explanatory power, pointing to paramount importance of species' life-history strategies. Taller plants showed later timing of initial growth, and flowered, fruited and underwent leaf senescence later. Large-leaved species had shorter flowering and fruiting durations. Taller, large-leaved species differ in their phenology and are more competitive than smaller, small-leaved species. We assume climate warming will change plant communities' competitive hierarchies with consequences for biodiversity.

Patterns and predictors of fleshy fruit phenology at five international botanical gardens.

PREMISE OF THE STUDY: To improve our understanding of the patterns and drivers of fleshy fruit phenology, we examined the sequence, patterns across years and locations, and drivers of fruiting times at five botanical gardens on three continents. METHODS: We monitored four stages of fruit phenology for 406 temperate, fleshy-fruited, woody plant species in 2014 and 2015. KEY RESULTS: Across all gardens, ripe fruits were present from May to March of the following year, with peak fruiting durations ranging from under 1 week to over 150 days. Species-level first fruiting and onset of peak fruiting dates were strongly associated with one another within sites and were more consistent between years and sites than the end of peak fruiting and last fruiting date. The order of fruiting among species between years and gardens was moderately consistent, and both peak fruiting times and fruiting durations were found to be phylogenetically conserved. CONCLUSIONS: The consistent order of fruiting among species between years and locations indicates species-specific phenological responses to environmental conditions. Wide variation in fruiting times across species and in the duration of peak fruiting reinforces the importance of understanding how plant phenology impacts dispersers and monitoring the health and consistency of these interactions.

Substantial variation in leaf senescence times among 1360 temperate woody plant species: implications for phenology and ecosystem processes.

BACKGROUND AND AIMS: Autumn leaf senescence marks the end of the growing season in temperate ecosystems. Its timing influences a number of ecosystem processes, including carbon, water and nutrient cycling. Climate change is altering leaf senescence phenology and, as those changes continue, it will affect individual woody plants, species and ecosystems. In contrast to spring leaf out times, however, leaf senescence times remain relatively understudied. Variation in the phenology of leaf senescence among species and locations is still poorly understood. METHODS: Leaf senescence phenology of 1360 deciduous plant species at six temperate botanical gardens in Asia, North America and Europe was recorded in 2012 and 2013. This large data set was used to explore ecological and phylogenetic factors associated with variation in leaf senescence. KEY RESULTS: Leaf senescence dates among species varied by 3 months on average across the six locations. Plant species tended to undergo leaf senescence in the same order in the autumns of both years at each location, but the order of senescence was only weakly correlated across sites. Leaf senescence times were not related to spring leaf out times, were not evolutionarily conserved and were only minimally influenced by growth habit, wood anatomy and percentage colour change or leaf drop. These weak patterns of leaf senescence timing contrast with much stronger leaf out patterns from a previous study. CONCLUSIONS: The results suggest that, in contrast to the broader temperature effects that determine leaf out times, leaf senescence times are probably determined by a larger or different suite of local environmental effects, including temperature, soil moisture, frost and wind. Determining the importance of these factors for a wide range of species represents the next challenge for understanding how climate change is affecting the end of the growing season and associated ecosystem processes.

Leaf out times of temperate woody plants are related to phylogeny, deciduousness, growth habit and wood anatomy.

Leaf out phenology affects a wide variety of ecosystem processes and ecological interactions and will take on added significance as leaf out times increasingly shift in response to warming temperatures associated with climate change. There is, however, relatively little information available on the factors affecting species differences in leaf out phenology. An international team of researchers from eight Northern Hemisphere temperate botanical gardens recorded leaf out dates of c. 1600 woody species in 2011 and 2012. Leaf out dates in woody species differed by as much as 3 months at a single site and exhibited strong phylogenetic and anatomical relationships. On average, angiosperms leafed out earlier than gymnosperms, deciduous species earlier than evergreen species, shrubs earlier than trees, diffuse and semi-ring porous species earlier than ring porous species, and species with smaller diameter xylem vessels earlier than species with larger diameter vessels. The order of species leaf out was generally consistent between years and among sites. As species distribution and abundance shift due to climate change, interspecific differences in leaf out phenology may affect ecosystem processes such as carbon, water, and nutrient cycling. Our open access leaf out data provide a critical framework for monitoring and modelling such changes going forward.

Synthetic and structural studies on macrocyclic amino cyclitols--conformational chameleons.

Starting from quinic acid the synthesis of 1,4-butanediol-linked macrocyclic aminocyclitols 30, 32, 34, 36 and 38 is described. Assembly was achieved by olefin cross-metathesis of appropriate cyclohexyl allyl ethers followed by ring-closing metathesis of bis-O-allyl homodimers. In all five cases studied, the only products that were formed were those resulting from direct ring-closing metathesis; the formation of larger rings was not detected. These macrocycles exhibited diverse conformational behaviour which included formation of stable separable conformers 31a and 31b as well as conformationally dynamic macrocycles 35 in which a ring flip in one cyclohexane chair conformer induces a ring flip of the other cyclohexane ring through the linking chains of the macrocycles. The activation energy for the inversion of the chair conformation in this process was determined to be about 38 kJ mol(-1), which is about 7 kJ mol(-1) lower than the activation energy for the ring flip of the unsubstituted cyclohexane ring. In all cases, the conformational studies strongly suggest that intramolecular H-bonding between 1,3-diaxially oriented amido and alcohol or ether groups exerts a decisive contribution to the overall stabilisation of the preferred cyclohexane chair conformation.

Atropisomeric 3-aryl-2-oxo-4-oxazolidinones and some thione analogues--enantiodifferentiation and ligand competition in applying the dirhodium method.

The atropisomeric 2-oxo-4-oxazolidinones 1Z bind weakly to the rhodium atoms in the complex Rh(II)2 [(R)-(+)-MTPA]4 (Rh*, MTPA-H = methoxytrifluoromethylphenylacetic acid identical with Mosher's acid), presumably via the C-2 carbonyl oxygen atom. There are some 1H and 13C NMR signals in these compounds which show small dispersion effects suitable for enantiodifferentiation. In contrast, the thiocarbonyl sulfur atoms in 2Z and 3Z bind strongly so that significant complexation shifts (Delta delta) and diastereomeric dispersion effects (Delta nu) can be observed, and chiral discrimination and the determination of enantiomeric ratios of these thiocarbonyl compounds is easy. So, it is shown that--as expected--C=S is a much better binding site when competing with C=O. In compounds of Series 2 a "syn-methyl effect" was discovered which describes the dependence of dispersion effects of syn-oriented methyl groups 6 on the nature of the substituents Z. A mechanism of combined steric and electronic interaction influencing the conformational equilibria inside the adducts is proposed. Determination of absolute configurations by correlation fails, at least on the basis of the data available.

The first cyclopentadienylalkylphosphane nickel chelates: synthesis, structures, and reactions.

The first cyclopentadienylalkylphosphane nickel chelate complexes are reported. The anionic ligand obtained by reaction of spiro[2.4]hepta-4,6-diene with lithium di-tert-butylphosphide was treated with NiCl2 to yield [eta(5):kappa(1)-(di-tert-butylphosphanylethyl)cyclopentadienyl]chloronickel(II). From this complex, some acetonitrile-stabilized cationic complexes were obtained by reaction with the respective silver salts in acetonitrile. Methyl- and alkynylnickel chelates were prepared by reaction of the chloronickel complex with methyllithium and by copper-mediated coupling with terminal alkynes, respectively. Some of the complexes prepared were investigated by X-ray crystallography or cyclic voltammetry. The alkynylnickel chelates undergo cycloaddition reactions with ethoxycarbonylisothiocyanate or tetracyanoethylene, and the cyclobutenes obtained undergo ring opening to the corresponding dienes. The study includes an NMR spectroscopic investigation of the two conformers of one of these dienes.

Odor-active alcohols from the fungal transformation of alpha-farnesene.

Submerged microbial cultures were screened for their potential to oxifunctionalize alpha-farnesene. The major oxidation product in all transforming cultures, 3,7,11-trimethyldodeca-1,3(E),5(E)10-tetraen-7-ol, showed a pleasant citrus-like odor and peak concentrations of 170 mg L-1. An Aspergillus niger isolate from mango generated another two terpene alcohols identified as diastereomeric menth-1-en-3-[2-methyl-1,3-butadienyl]-8-ol, a new natural compound with an apricot-like odor. The regiospecifity of the oxygen attack with concurrent lack of stereoselectivity suggested that the initial step of the bioconversion resembled the chemical autoxidation starting with the generation of an intermediate resonance-stabilized carbon-centered radical or carbocation.

Synthesis, characterization, and 32P-postlabeling of N-(deoxyguanosin)-4-aminobiphenyl 3'-phosphate adducts.

The (32)P-postlabeling assay is an extremely sensitive technique for detecting carcinogen-DNA adducts. However, for the assignment of DNA adduct structures and the accurate determination of DNA adduct levels by (32)P-postlabeling, authentic adduct standards are needed. For most (32)P-postlabeling applications, such verified synthetic standard compounds are required in the form of their deoxynucleoside 3'-phosphates because they represent substrates for the polynucleotide kinase for transfer of [(32)P]phosphate from [gamma-(32)P]ATP. Three N-(deoxyguanosin)-4-aminobiphenyl 3'-phosphate adducts were prepared and fully characterized by (1)H NMR and mass spectroscopy to serve as standards for the (32)P-postlabeling assay. Apart from the C8- and the N(2)-deoxyguanosine 3'-phosphate adducts of the mutagenic human bladder carcinogen 4-aminobiphenyl (dG3'p-C8-4-ABP and dG3'p-N(2)-4-ABP), the C8-deoxyguanosine 3'-phosphate adduct of the nonmutagenic 4'-tert-butyl-4-aminobiphenyl (dG3'p-C8-4'tBu-4-ABP) was included in the study. Both C8-deoxyguanosine 3'-phosphate adducts were prepared by the in situ formation of deoxyguanosine 3'-phosphate and its subsequent reaction with the appropriate electrophilic amination agent (N-acetoxy compound). The N(2)-deoxyguanosine 3'-phosphate adduct was obtained by a modification of a previously described procedure for the synthesis of N(2)-deoxyguanosine adducts of aromatic amines. The three adduct standards were added at different concentrations to calf thymus DNA, and adduct recoveries were determined by the (32)P-postlabeling assay under conditions routinely used in the standard methodology, enhancement by nuclease P1 digestion and enhancement by butanol extraction. The dG3'p-C8-4-ABP adduct was recovered irrespective of the concentration with approximately 30% in both the standard and the butanol extraction version of the assay. Both C8-deoxyguanosine 3'-phosphate adducts were sensitive to nuclease P1 digestion resulting in recoveries of only 1-3%. In contrast, the dG3'p-N(2)-4-ABP adduct was resistant to nuclease P1 digestion; however, recovery in all three versions was poor (1-2%) resulting in a detection limit of one adduct/10(6) nucleotides. These results demonstrate that the (32)P-postlabeling assay underestimates the level of DNA adducts formed by 4-ABP and indicates that there is a need to determine the recovery for each adduct to be analyzed by the (32)P-postlabeling technique.

Crystal Structure of a Peptide-Steroid Macrocycle-Intramolecular Attraction between Steroids and Peptidic ß(I) Turns.

Two molecules of the steroid lithocholic acid and two dipeptides (Phe-Phe) make up the macrocycle 1, in which the two steroidal surfaces approach each other so that the peptide parts fold into ß(I) turns. Thus, the structure of a cyclic steroid-peptide compound was determined in the solid state for the first time. The structure of 1 is stabilized in the crystal through intra- and intermolecular hydrogen bonds as well as through π stacking of the side-chain phenyl rings of Phe(i+1).