Nectar sugar composition of European Caryophylloideae (Caryophyllaceae) in relation to flower length,pollination biology and phylogeny

Floral nectar composition has been explained as an adaptation to factors that are either directly or indirectly related to pollinator attraction. However, it is often unclear whether the sugar composition is a direct adaptation to pollinator preferences. Firstly, the lower osmolality of sucrose solutions means that they evaporate more rapidly than hexose solutions, which might be one reason why sucrose‐rich nectar is typically found in flowers with long tubes (adapted to long‐tongued pollinators), where it is better protected from evaporation than in open or short‐tubed flowers. Secondly, it can be assumed that temperature‐dependent evaporation is generally lower during the night than during the day so that selection pressure to secrete nectar with high osmolality (i.e. hexose‐rich solutions) is relaxed for night‐active flowers pollinated at night. Thirdly, the breeding system may affect selection pressure on nectar traits; that is, for pollinator‐independent, self‐pollinated plants, a lower selective pressure on nectar traits can be assumed, leading to a higher variability of nectar sugar composition independent of pollinator preferences, nectar accessibility and nectar protection. To analyse the relations between flower tube length, day vs. night pollination and self‐pollination, the nectar sugar composition was investigated in 78 European Caryophylloideae (Caryophyllaceae) with different pollination modes (diurnal, nocturnal, self‐pollination) using high‐performance liquid chromatography (HPLC). All Caryophylleae species (Dianthus and relatives) were found to have nectar with more than 50% sucrose, whereas the sugar composition of Sileneae species (Silene and relatives) ranged from 0% to 98.2%. In the genus Silene, a clear dichotomous distribution of sucrose‐ and hexose‐dominant nectars is evident. We found a positive correlation between the flower tube length and sucrose content in Caryophylloideae, particularly in day‐flowering species, using both conventional analyses and phylogenetically independent contrasts.     

Floral and vegetative morphometrics of three Platonia insignis Mart. (Clusiaceae) populations,a native tree from the Brazilian Amazon

Platonia insignis Mart. (Clusiaceae), the bacurizeiro, is a native tree species from the Brazilian Amazon forests. Three populations of P. insignis have been observed in the north-east region of the state of Maranhão that differ in flower color: the red population that produces dark pink flowers, the pink population that produces light pink flowers, and the white population with yellowish-white flowers. From multivariate statistical analysis, we aimed at characterizing such populations using morpho-anatomical leaf and flower morphology parameters. A total of 40 P. insignis individuals have been sampled in the cities of São Luís and Chapadinha. The morphological traits varied more than the anatomical traits. Area, fresh mass, and dry mass were the leaf parameters that show more variations. Platonia insignis have hypostomatic or amphihypostomatic leaves. The length of the gynoecium+the length of the nectary, the total length and the length of gynoecium were the principal components considering flower analysis. The three populations did not show significant differences nor did they group using Ward's method. Individuals from the Chapadinha and São Luís red population have been separated according to leaf and flower morphological traits, and the morphological difference between individuals may represent early stages of geographical speciation.     

Development Of A Nucleic Acid Lateral Flow Strip For Detection Of Hepatitis C Virus (Hcv) Core Antigen

The object of this study was to develop a simple, rapid, specific, and highly sensitive method to detect HCV core antigen. A nucleic acid aptamer was designed with the high specificity and sensitivity in a nucleic acid lateral flow strip to compete with HCV core antigen and DNA probes. The lower detection limit of the test strip was calculated to be 10 pg/mL with the scanner and 100 pg/mL with naked eyes. Results showed that there were no cross-interactions with other proteins such as HCV NS3, E1/E2 antigens, HIV p24 antigens, or BSA proteins (HCV unrelated protein). When the viral load exceeded 10⁴ copies/mL, the positive coincidence rates of ELISA and strip detection, when compared with the HCV RNA assay, were 98.44% and 97.28%, respectively. The results indicated that the ELISA detection and strip assay were in good agreement with the measured value. The results indicated that a nucleic acid lateral flow strip was a simple, rapid, specific, highly sensitive, and cost-effective field-based method for detecting HCV core antigen. The strip assay is an acceptable alternative to diagnose HCV core antigen and to investigate its epidemiology in clinical laboratories lacking specialized equipment and skills.     

Positive association between thrips and spider mites in seedling cotton

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Phenylacetaldehyde attracts male and female apple clearwing moths,Synanthedon myopaeformis,to inflorescences of showy milkweed,Asclepias speciosa

Synanthedon myopaeformis Borkhausen (Lepidoptera: Sesiidae) is a diurnal clearwing moth native to Eurasia that was recently introduced into British Columbia (BC) and Ontario, Canada, where it has become a serious pest in apple orchards. In BC, these moths commonly feed on nectar of inflorescences, particularly that of showy milkweed, Asclepias speciosa Torrey (Apocynaceae). We investigated the relative importance of visual and olfactory cues, and the key floral semiochemical(s) mediating attraction of S. myopaeformis to A. speciosa. In field experiments, inflorescences left exposed or enclosed in cheesecloth bags dyed green induced similar visitation rates by moths, indicating that olfactory cues are attractive. Among the >10 floral odourants that elicited responses from moth antennae in coupled gas chromatographic‐electroantennographic detection analyses, phenylacetaldehyde induced the most frequent proboscis extension reflexes of male and female moths. Among eight floral odourants that were field‐tested singly, phenylacetaldehyde attracted 35 times more male and female moths than any other candidate semiochemical. Attractiveness of phenylacetaldehyde could not be enhanced by admixture with other floral odourants at the ratios or concentrations tested indicating that it alone may mediate attraction of S. myopaeformis to the inflorescences of A. speciosa. The potential use of phenylacetaldehyde as bait to monitor or mass‐trap populations of male and female S. myopaeformis should be investigated.     

红光与远红光比值对温室切花菊花‘神马’花芽分化进程的影响

以切花菊品种‘神马’(Chrysanthemum morifolium cv.‘Jingba’)为试材,设计红光(R:660±10 nm)与远红光(FR:730±10 nm)比值(R/FR)为0.5、2.5、4.5、6.5的LED照光处理,研究不同R/FR处理对菊花花芽分化进程、相对发育速率及花径的影响.结果表明:R/FR=6.5处理的菊花完成花芽分化进程所需时间最短,比R/FR=0.5处理下的菊花缩短了34 d.R/FR越大,菊花花芽分化的相对发育速率越大,完成花芽分化时,R/FR=6.5相对发育速率为R/FR=0.5的2倍.与花芽分化趋势一致,不同光质处理下的花径由大到小的R/FR顺序为:6.5＞4.5＞2.5＞0.5.本研究表明,R/FR=6.5能够显著促进菊花花芽分化进程和花径的生长.     

The function of the wild carrot's dark central floret: attract,guide or deter?

Although Charles Darwin wrote about flower polymorphism in the wild carrot, Daucus carota, the function of the conspicuous central dark floret is still unclear. We used video recordings to evaluate the functional significance of the dark central floret as a short‐distance signal for insects landing on the umbels and analyzed the location of landing points, landing orientation and visit duration. These parameters, as well as insect attraction did not differ on umbels with and without a dark central floret. Hence, we found no evidence for the role of the dark central floret in the pollination of D. carota. Umbels with a dark central floret, however, were parasitized significantly less often by the gall midge Kiefferia pericarpiicola than umbels without a dark central floret. We propose that the dark central floret may play a role in reducing parasite infestation by mimicking an already present gall or deterring oviposition of the gall midge by other means.     

Production of 2-Phenylethanol in Roses as the Dominant Floral Scent Compound from L-Phenylalanine by Two Key Enzymes,a PLP-Dependent Decarboxylase and a Phenylacetaldehyde Reductase

We investigated the biosynthetic pathway for 2-phenylethanol, the dominant floral scent compound in roses, using enzyme assays. L-[²H₈] Phenylalanine was converted to [²H₈] phenylacetaldehyde and [²H₈]-2-phenylethanol by two enzymes derived from the flower petals of R. ‘Hoh-Jun,’ these being identified as pyridoxal-5′-phosphate-dependent L-aromatic amino acid decarboxylase (AADC) and phenylacetaldehyde reductase (PAR). The activity of rose petal AADC to yield phenylacetaldehyde was nine times higher toward L-phenylalanine than toward its D-isomer, and this conversion was not inhibited by iproniazid, a specific inhibitor of monoamine oxidase. Under aerobic conditions, rose petal AADC stoichiometrically produced NH₃ together with phenylacetaldehyde during the course of decarboxylation and oxidation, followed by the hydrolysis of L-phenylalanine. Phenylacetaldehyde was subsequently converted to 2-phenylethanol by the action of PAR. PAR showed specificity toward several volatile aldehydes.     

Molecular Weight Determination of Component Polypeptides of Glutenin after Fractionation by Gel Filtration

Reduced and cyanoethylated glutenin was fractionated into three fractions (F I, F II and F III) by gel filtration on Sephadex G–100 in 0.1 m acetic acid. The molecular weight determination was made with these three fractions by sedimentation equilibrium in 6.5 m guanidine hydrochloride containing 0.01 m acetic acid. The molecular weight obtained was 44,000 for F II, and 32,000 for F III. F I showed a distribution of molecular weight due to the aggregation. The average molecular weight of F I was 52,000, being 27,000 at the meniscus and 98,000 at the bottom. The estimation of molecular weight by SDS–PAGE* gave overestimated values for glutenin polypeptides, as was already reported for gliadin.