濒危植物中甸刺玫种子休眠及其生态学意义

对中甸刺玫Rosa praelucens种子结构及其透水性,赤霉素处理对胚的影响,果壳、种皮、胚乳的粗提物活性进行研究。结果表明：(1) 中甸刺玫外种皮是由多层排列紧密的厚壁细胞组成,内种皮为坚硬致密的栅栏组织;(2) 种皮对种子的吸胀阻碍较大, 未处理的种子吸水率较低,吸水13 d后增加量为18.82%;(3) 果实结籽率为0.69%,多数果实中没有饱满的种子;(4) 赤霉素100 mg·kg-1预处理种子可加快胚的萌发速率;(5) 胚乳、种皮、果壳中存在内源抑制物。中甸刺玫种子的休眠是由其形态和生理特点引起的综合休眠。     

Heterogeneous inhibition of photosynthesis over the leaf surface of Rosa rubiginosa L. during water stress and abscisic acid treatment: induction of a metabolic component by limitation of CO2 diffusion

The contribution of changes in stomatal conductance and metabolism in determining heterogeneous photosynthesis inhibition during dehydration and abscisic acid (ABA) feeding was investigated using detached leaves of Rosa rubiginosa L. The steady-state and maximal rates of electron transport under a transient high CO₂ concentration were monitored using chlorophyll fluorescence imaging. The decrease in electron transport rate induced by dehydration and ABA treatment almost reverted to the control rate under transient high CO₂ availability. Therefore, inhibition of photosynthesis was mainly mediated through stomatal closure. However, since reversion was not complete, a metabolic inhibition was also identified as a decrease in the maximal electron transport rate driven by carboxylation. Under dehydration or ABA feeding, as under low ambient CO₂ treatment, in 21% or 0.4% O₂, the lower the steady-state electron transport was, the lower was the maximal electron transport rate during transient high CO₂ availability. We conclude that low CO₂ availability reduced the capacity of ribulose-1,5-bisphosphate carboxylase-oxygenase (Rubisco) to drive electron transport. The potential contribution of Rubisco deactivation mediated by stomatal closure is discussed. Received: 1 February 1999 / Accepted: 15 June 1999     

A simple protocol for isolating genomic DNA from chestnut rose (<Emphasis Type="Italic">Rosa roxburghii</Emphasis> tratt) for RFLP and PCR analyses

Isolation of high-quality DNA from rosaceous species is particularly difficult because of their high levels of polyphenols, polysaccharides, and other compounds. The yields and quality of genomic DNA are considerably affected when the common protocol for DNA isolation is applied to the chestnut rose (Rosa roxburghii Tratt). A simple, rapid, and efficient protocol for the extraction of DNA from the chestnut rose is described. The modified hexadecyltrimethylammonium bromide (CTAB) procedure, which uses phenol-absent extraction to enhance the yield, involves a washing step before extraction for the removal of organic molecules and excessive water; the use of high concentrations of polyvinylpyrrolidone (2% [w/v]), CTAB (3% [w/v]), and β-mercaptoethanol (3% [v/v]) in the high-salt-concentration extraction buffer to remove polyphenols and polysaccharides; and the combined use of potassium acetate and chloroform to remove proteins and polysaccharides. Finally, DNA is precipitated with an equal volume of isopropanol and 0.1 vol of sodium acetate. This protocol results in high yields of DNA. The average yield of DNA ranged from 980–1800 μg/g of fresh weight of leaves. Downstream results indicate that DNA quality is sufficient for restriction fragment length polymorphism (RFLP) and polymerase chain reaction (PCR) analyses.     

Effects of temperature on phyllody expression and cytokinin content in floral organs of rose flowers

Formation of leaf-like organs known as phylloids in Rosahybrida cv. Motrea flowers was promoted by exposure of plants toelevated temperatures. At a day/night temperature regime of26°C/21°C respectively theproportion of malformed flowers exhibiting phyllody was four times higher thanthat in flowers of plants grown at21°C/15°C. The number ofpetals in phyllody-expressing flowers was higher than that in normal flowers.The total content of endogenous cytokinins in young flower buds of plantsexposed to the lower temperature was six times higher than that at the highertemperatures. The effects of the reduced temperature were pronounced on all thegroups of cytokinins examined. However, the proportion of the various cytokiningroups remained similar at both temperature regimes. In contrast to thecytokinins in the flower buds, the content of all cytokinin types in youngleaves increased following exposure to the higher temperature and was reducedbythe lower temperatures. After 11 weeks at the lower temperature, about18% of the flowers remained malformed, whereas at the higher temperatureabout 20% of the flowers still remained normal. All thephyllody-exhibiting flowers were formed on vigorously grown basal shootscharacteristic to Rosa hybrida plants, whereas the normalflowers at the elevated temperatures were formed on lateral shoots which weremost distal to the plant base. However, irrespective of the season, thepresenceof normal and malformed flowers was observed on plants kept growing at standardconditions of 30°C/17°C inthegreenhouse. This phenomenon led us to examine the cytokinins in floral organsofnormal and malformed cv. Motrea flowers grown in the greenhouse as well as inflowers of a complete rose mutant known as a 'Green Rose(Rosa chinensis viridiflora). The highest content ofcytokinins was found in the pistils and stamens of normal 'Motreaflowers. On the other hand, the content of cytokinins in leaf-like style-tubesin the malformed flowers as well as in partially malformed ovaries at the baseof phylloids was significantly lower. A low content of cytokinins was alsopresent in petals of both normal and phyllody-exhibiting flowers and the lowestcontent has been found in the phylloids of the 'Green Rose. Apossibility of mutant deviations in metabolism of cytokinins in rose plants isdiscussed.     

AFLP-based estimation of 2n gametophytic heterozygosity in two parthenogenetically derived dihaploids of Rosa hybrida L

Two dihaploid Rosa hybrida L. genotypes, derived through parthenogenesis by using irradiated pollen, were crossed with clonally propagated plants of the diploid species Rosa rugosa Thunb. and Rosa wichuraiana Crép., respectively. Three progeny groups were obtained which contained numerous polyploids, as determined by flow cytometry. Production of fertile 2n female gametes is apparently very common in one of these R. hybrida dihaploid derivatives, whereas the other one is able to produce fertile 2n pollen. Hence, an amplified fragment length polymorphism (AFLP) study was performed on the parental plants and the resulting hybrid offspring in order to estimate (1) the respective genomic parental contributions, and (2) the level of heterozygosity transmitted by the 2n unreduced gametes. Comparison of the levels of transmitted parental heterozygosity revealed that two types of 2n gametes were produced simultaneously, presumably resulting from restitution at the first and at the second meiotic division, respectively. Received: 15 February 2001 / Accepted: 22 May 2001     

Effect of Elevated CO2 on Photosynthesis and Chlorophyll Fluorescence of Rose Plants Grown at High Temperature and High Photosynthetic Photon Flux Density

Gas exchange and chlorophyll (Chl) fluorescence were measured on young mature leaves of rose plants (Rosa hybrida cvs. First Red and Twingo) grown in two near-to-tight greenhouses, one under control ambient CO₂ concentration, AC (355 µmol mol^–1) and one under CO₂ enrichment, EC (700 µmol mol^–1), during four flushes from late June to early November. Supply of water and mineral elements was non-limiting while temperature was allowed to rise freely during daytime. Leaf diffusive conductance was not significantly reduced at EC but net photosynthetic rate increased by more than 100 %. Although the concentration of total non-structural saccharides was substantially higher in the leaves from the greenhouse with EC, _PS2 (quantum efficiency of radiation use) around noon was not significantly reduced at EC indicating that there was no down-regulation of electron transport. Moreover, CO₂ enrichment did not cause any increase in the risk of photo-damage, as estimated by the 1 – q_P parameter. Non-photochemical quenching was even higher in the greenhouse with EC during the two summer flushes, when temperature and photosynthetic photon flux density (PPFD) were the highest. Hence rose photosynthesis benefits strongly from high concentrations of atmospheric CO₂ at both high and moderate temperatures and PPFD.     

Diphenylene iodonium sensitivity of a solubilized membrane enzyme from rose cells

Summary An NADH-specific oxidation reduction enzyme has been partially purified from rose cell microsomes by aqueous two-phase partitioning, ultracentrifugation, and ion-exchange chromatography, on the basis of the enzyme's ability to activate lucigenin chemiluminescence in the presence of NADH. The enzyme showed strong similarity to a plasma membrane NADH oxidase (superoxide synthase as assayed by lucigenin chemiluminescence; T. M. Murphy and C.-K. Auh, Plant Physiol. 110: 621–629, 1996) in its response to substrate, to Triton X-100, and to diphenylene iodonium, an inhibitor of mammalian neutrophil NADPH oxidase and other flavoenzymes. However, its fluorescence spectrum was not characteristic of flavins and instead was similar to that of pterins. Thus inhibition of an enzyme-catalyzed reaction by diphenylene iodonium does not necessarily imply that the reaction is catalyzed by NADPH oxidase or another flavoenzyme. Superoxide synthesis catalyzed by the enzyme preparation was very low but could be increased at least twofold by the addition of a quinone, menadione. This suggests the enzyme acting in conjunction with a natural quinone could produce activated oxygen species in stressed plant cells.Abbreviation DPI diphenylene iodonium     

Expression of a chitinase transgene in rose (Rosa hybrida L.) reduces development of blackspot disease (Diplocarpon rosae Wolf)

Blackspot, caused by the Ascomycete fungus Diplocarpon rosae, is the most widespread and pernicious disease of cultivated roses. While some species of rose possess resistance to D. rosae, none of the modern-day rose cultivars are fully resistant to the pathogen. In the current study, Biolistic gene delivery was used to introduce a rice gene, encoding a basic (Class I), chitinase into embryogenic callus of the blackspot-susceptible rose (Rosa hybrida L.) cv. Glad Tidings. The plasmid used for transformation carried the neomycin phosphotransferase (nptII) gene facilitating the selection and regeneration of transgenic plants on medium containing 250 mg/l kanamycin. Southern analysis confirmed integration of 2–6 copies of the chitinase gene into the rose genome; gene expression was confirmed by enzyme assay. Bioassays demonstrated that expression of the chitinase transgene reduced the severity of blackspot development by 13–43%. This degree of resistance to the pathogen correlated with the level of chitinase expression in the transgenic rose plants. The introduction of disease defence genes into rose provides a method of producing blackspot-resistant rose cultivars sought by breeders and growers.     

Chromosome doubling in a <Emphasis Type="Italic">Rosa rugosa</Emphasis> Thunb. hybrid by exposure of in vitro nodes to oryzalin: the effects of node length,oryzalin concentration and exposure time

Chromosome doubling was induced in vitro in a diploid hybrid of Rosa rugosa Thunb. using oryzalin as the spindle inhibitor. Nodal sections, 2 mm long, were exposed to 2.5 or 5 μM oryzalin and 10 mm nodal sections were exposed to 5 μM oryzalin for 0 (controls), 6, 12, 24 and 48 h. The ploidy of the emergent shoots was determined by flow cytometry. The frequency of tetraploid and mixoploid leaves that developed from 2 mm nodal sections exposed to 5 μM oryzalin peaked at 12 h exposure, when 35% of the leaves were tetraploid, but fell after longer exposures. Fewer tetraploid and mixoploid leaves were found when 2 mm nodes were exposed to 2.5 μM oryzalin for 6 and 12 h, indicating that it took longer for a spindle inhibiting concentration of oryzalin to build up in the meristem. However, the frequencies of tetraploid and mixoploid leaves continued to rise after 12 h and were highest at 48 h, when 44% were tetraploid. In treatments with 5 μM oryzalin, the frequencies of tetraploid and mixoploid leaves were lower, at equivalent exposure times, in 10 mm nodes than 2 mm nodes. This suggests that oryzalin diffused to the meristem mainly via the cut surfaces and that access via the epidermis and cuticle was impeded.