Pollen mother cells of Tradescantia clone 4430 and Tradescantia pallida var. purpurea are equally sensitive to the clastogenic effects of X-rays.
The Tradescantia micronucleus test is a sensitive bioassay for mutagenesis that may be employed both under field and laboratory conditions. This test has been standardized mostly on the basis of the results obtained with clone 4430. However, this clone is not well adapted to tropical weather, frequently showing problems with growth and flowering. In addition, it is attacked by parasites and insects, a fact that limits its use in field studies aiming at the biomonitoring of air pollution. In the city of Sao Paulo, Tradescantia pallida (Rose) Hunt. var. purpurea Boom is widely distributed as an ornamental plant in gardens and along roadsides and streets, mostly because of its natural resistance and its easy propagation. In this report, we present dose-response curves indicating that the sensitivity of T. pallida and clone 4430 to X-radiation (1, 10, 25 and 50 cGy) is similar. The results confirm our previous suggestion that T. pallida represents a good alternative for in situ mutagenesis testing in tropical regions, especially biomonitoring studies in which the exposure conditions may not be fully controllable. (+info)
Effects of herbivory on the reproductive effort of 4 prairie perennials.
BACKGROUND: Herbivory can affect every aspect of a plant's life. Damaged individuals may show decreased survivorship and reproductive output. Additionally, specific plant species (legumes) and tissues (flowers) are often selectively targeted by herbivores, like deer. These types of herbivory influence a plant's growth and abundance. The objective of this study was to identify the effects of leaf and meristem removal (simulated herbivory within an exclosure) on fruit and flower production in four species (Rhus glabra, Rosa arkansana, Lathyrus venosus, and Phlox pilosa) which are known targets of deer herbivory. RESULTS: Lathyrus never flowered or went to seed, so we were unable to detect any treatment effects. Leaf removal did not affect flower number in the other three species. However, Phlox, Rosa, and Rhus all showed significant negative correlations between seed mass and leaf removal. Meristem removal had a more negative effect than leaf removal on flower number in Phlox and on both flower number and seed mass in Rosa. CONCLUSIONS: Meristem removal caused a greater response than defoliation alone in both Phlox and Rosa, which suggests that meristem loss has a greater effect on reproduction. The combination of leaf and meristem removal as well as recruitment limitation by deer, which selectively browse for these species, is likely to be one factor contributing to their low abundance in prairies. (+info)
Analysis of gene expression in rose petals using expressed sequence tags.
Single-pass sequences were obtained from the 5'-ends of a total of 1794 rose petal cDNA clones. Cluster analysis identified 242 groups of sequences and 635 singletons indicating that the database represents a total of 877 genes. Putative functions could be assigned to 1151 of the transcripts. Expression analysis indicated that transcripts of several of the genes identified accumulated specifically in petals and stamens. The cDNA library and expressed sequence tag database described here represent a valuable resource for future research aimed at improving economically important rose characteristics such as flower form, longevity and scent. (+info)
Characterization of two CTR-like protein kinases in Rosa hybrida and their expression during flower senescence and in response to ethylene.
The expression of two CTR-gene homologues was investigated during flower senescence in two Rosa hybrida cultivars. A fragment of a gene for a protein kinase, termed RhCTR1 (GenBank Acc. No. AF271206), was amplified by PCR and used to isolate the corresponding full-length cDNA (Acc. No. AY032953) from a rose petal cDNA library. The protein RhCTR1 has 66% amino acid identity to Arabidopsis CTR1. A fragment of a second CTR homologue, termed RhCTR2 (Acc. No. AY029067) is 69% identical to the corresponding region of RhCTR1. RhCTR1 expression increased during flower senescence, while RhCTR2 was constitutively expressed during flower development. The expression of both RhCTR1 and RhCTR2 was increased in response to exogenous ethylene. (+info)
Allergic rhinitis in Rosa domescena cultivators: a novel type of occupational allergy?
After the diagnosis of allergic rhinitis due to Rosa domescena was suspected in one subject with skin prick and nasal provocation tests, we recruited all other workers employed in rose cultivation in Yakaoren village, Isparta. From May 2000 to July 2000 (exposure period 'time of rose handling'), we studied 600 individuals employed in rose cultivation. A questionnaire was administered by a physician, and skin testing was done by a nurse on 75 individuals suffering from asthma and/or rhinitis. Sera from these 75 subjects were available for immunologic testing. The diagnosis of atopy against rose was based on the presence of work-related symptoms, positive skin prick test (SPT) with rose extracts, and positive RAST. While no subject reported asthmatic symptoms, twenty of them reported either rhino-conjunctivitis, rhinitis or both on exposure to Rosa domescena. Fourteen of these subjects had increased specific IgE levels to Rosa domescena. Eleven (78.5%) also had a positive skin reaction to Rosa domescena. Out of the six negative sera with normal specific IgE levels to rose, only two (33.3%) had positive skin reactivity. No subject had significant daily peak expiratoy flow rate (PEFR) variations. We conclude that exposure to Rosa domescena may represent a risk for allergic rhinitis. The possibility of an occupational rose allergy should therefore be taken into consideration in the subjects working in rose cultivation. (+info)
Extreme resistance to desiccation and microclimate-related differences in cold-hardiness of gall wasps (Hymenoptera: Cynipidae) overwintering on roses in southern Canada.
Four species of cynipid wasp of the genus Diplolepis that induce galls on roses (Rosa species) in southern Canada and two species of inquiline cynipid associated with these galls were studied for their cold-hardiness and resistance to water loss and for possible links between these adaptations. Mid-winter-acclimated supranivean D. spinosa and Periclistus pirata had lower supercooling points (-38 to -40 degrees C) and higher hemolymph osmolalities (1760-1849 mosmol kg(-1)) than subnivean D. polita, D. gracilis, D. radicum and Periclistus sp. (-31 to -32 degrees C and 977-1464 mosmol kg(-1), respectively). During a simulated transition from summer/fall to mid-winter conditions, the glycerol concentration of D. spinosa more than tripled, reaching a final value of 0.98 moll(-1), while its supercooling point decreased by 13 degrees C from the initial value of -27.4 degrees C; however, glycerol concentration and supercooling point did not change for the subnivean species. The permeability of the cuticle of all species was extremely low (0.33-1.00 microg h(-1) cm(-2) mmHg(-1) at 5 degrees C and 0 % relative humidity; 1 mmHg=0.133 kPa), even compared with that of desert species; however, there was no difference in cuticular permeability between supranivean and subnivean prepupae. Transition temperatures ranged between 32.3 and 34.6 degrees C; below 30 degrees C, temperature had little effect on rates of water loss for all species (Q(10)=1.13-1.87). (+info)
Biogenesis of 2-phenylethanol in rose flowers: incorporation of [2H8]L-phenylalanine into 2-phenylethanol and its beta-D-glucopyranoside during the flower opening of Rosa 'Hoh-Jun' and Rosa damascena Mill.
To clarify the biosynthetic pathway to 2-phenylethanol (2), the deuterium-labeled putative precursor, [2H8]L-phenylalanine ([2H8-1]), was fed to the flowers of Rosa 'Hoh-Jun' and R. damascena Mill. throughout maturation, ceasing feeding at the commencement of petal unfurling and at full bloom. Based on GC-MS analyses, [2H8]-1 was incorporated into both 2 and 2-phenylethyl beta-D-glucopyranoside (3) when the flowers were fed until full bloom, whereas no such incorporation into 2 was apparent when feeding was ceased earlier. In both species of rose, the labeling pattern for 2 was almost identical to that for 3, and indicated the presence of [2H6]-, [2H7]- and [2H8]-2, and [2H6]-, [2H7]- and [2H8]-3. This may be ascribed to the equilibrium between 2 and 3. The labeling pattern for 2 and 3 also indicated that these compounds were produced from 1 via several routes, the route involving phenylpyruvic acid being the major one. (+info)
Biosynthesis of the major scent components 3,5-dimethoxytoluene and 1,3,5-trimethoxybenzene by novel rose O-methyltransferases.
In Chinese rose species and in many modern varieties, two methylated phenolic derivatives, 3,5-dimethoxytoluene and 1,3,5-trimethoxybenzene, are major scent components. We show that cell-free extracts of rose petals catalyse the synthesis of 3,5-dimethoxytoluene and 1,3,5-trimethoxybenzene by methylation of precursor molecules. An expressed sequence tag approach was used to identify four highly similar O-methyltransferase sequences expressed specifically in petals and anthers. Thin layer chromatography analysis showed that the activities of these enzymes with different substrates and the proportions of reaction products produced closely mimicked those observed using cell-free petal extracts, indicating that orcinol O-methyltransferases are responsible for the biosynthesis of 3,5-dimethoxytoluene and 1,3,5-trimethoxybenzene from un-methylated precursors in this organ. (+info)