Produits neutres et alcaloides de Myrtopsis macrocarpa,M. myrtoidea,M. novae-caledoniae et M. sellingii

Stems and leaves of Myrtopsis macrocarpa, M. myrtoidea, M. novae-caledoniae and M. sellingii yielded terpenes, sterols, coumarins, alkaloids (furoquinolines and quinolones) and amides. A new quinolone (8-methoxy flindersine) occurs in Myrtopsis macrocarpa, a new amide (N-benzoyltryptamine) in M. myrtoidea, two new coumarins (myrsellin and myrsellinol) and a new dihydrofuroquinoline (myrtopsine) in M. sellingii. Structures of the new compounds are proposed from chemical and spectroscopic evidence.     

Chemosystematic evaluation of Aloe section Pictae (Asphodelaceae)

The chemosystematic value of UV-absorbing leaf constituents was considered in previously uncharacterised representatives of Aloe section Pictae, the problematic maculate species complex. Comparative data indicate that the anthrone C-glycoside, 6′-malonylnataloin (7-hydroxychrysaloin 6′-O-malonate) is typical of maculate species in East Africa, but is unconvincing as a synapomorphy for section Pictae. A naphthalene derivative found widely in Aloe, plicataloside, was detected in Aloe greatheadii. Biogeographical trends were observed in the occurrence of the flavonoids isoorientin (luteolin-6-C-glucoside) and isovitexin (apigenin 6-C-glucoside). Isoorientin is a common constituent of tropical and sub-tropical species of Aloe, whereas isovitexin is restricted to a few southern African species. Isoorientin and isovitexin co-occur in the southern African maculate species Aloe parvibracteata, and the disjunct West African maculate species, Aloe macrocarpa. This is the first report of isoorientin and isovitexin in maculate species of Aloe; the presence of flavonoids in section Pictae is of taxonomic interest.     

Chloroplastic and nuclear diversity of wild beets at a large geographical scale: Insights into the evolutionary history of the Beta section

Historical demographic processes and mating systems are believed to be major factors in the shaping of the intraspecies genetic diversity of plants. Among Caryophyllales, the Beta section of the genus Beta, within the Amaranthaceae/Chenopodiaceae alliance, is an interesting study model with species and subspecies (Beta macrocarpa, Beta patula, Beta vulgaris maritima and B.v. adanensis) differing in geographical distribution and mating system. In addition, one of the species, B. macrocarpa, mainly diploid, varies in its level of ploidy with a tetraploid cytotype described in the Canary Islands and in Portugal. In this study, we analyzed the nucleotide diversity of chloroplastic and nuclear sequences on a representative sampling of species and subspecies of the Beta section (except B. patula). Our objectives were (1) to assess their genetic relationships through phylogenetic and multivariate analyses, (2) relate their genetic diversity to their mating system, and (3) reconsider the ploidy status and the origin of the Canarian Beta macrocarpa.     

Ineffective nodulation of Sesbania macrocarpa by Sinorhizobium meliloti strain RCR2011

Sinorhizobium meliloti is a well-known symbiont that fixes nitrogen with plants of three genera of the family Leguminosae, Tribe Trifolieae: Medicago, Melilotus, and Trigonella. We have found that S. meliloti strain RCR2011 forms ineffective nodules on a distantly related legume species, Sesbania macrocarpa. Nodules are indeterminate and lack leghemoglobin. Although S. meliloti deformed root-hairs of S. macrocarpa, infection threads were not detected in these cells. Instead, cells of S. meliloti were found in infection pockets between cortical cells and within infection threads that had penetrated into these cells. Bacteria eventually were released and gave rise to symbiosomes, which contained large quantities of an amorphous matrix with parallel arrays of electron-dense striations. Mutants of strain RCR2011 lacking nodA or nodH failed to nodulate S. macrocarpa, inactivation of nodG or nodE resulted in smaller nodules, while inactivation of region IIa, which contains nodIJ, had no apparent effect on nodulation.     

Geographic differentiation of cortical monoterpenoids of Pseudotsuga macrocarpa

Cortical essential oil from Pseudotsuga macrocarpa was analyzed for monoterpenoid compounds. Only minor differences were apparent between samples collected in different locations. Pseudotsuga macrocarpa and P. menziesii appeared to be quite distinct chemically. No evidence was obtained of any gene exchange between the two species in the southern California coastal region, where they grow a short distance from each other.     

First report of fern (Culcita macrocarpa) spore consumption by a small mammal (Apodemus sylvaticus)

Few vertebrates are known to consume ferns regularly. Several species of mammals consume leaves to some extent but the consumption of fern spores is much rare. In Galicia (Northwest Spain) we studied the seasonal variation in the consumption of Culcita macrocarpa fertile leaves (i.e. with spores) in two populations (Capelada and Eume), assessed whether consumption rate increased with fern population size, and evaluated whether the consumer was a spore predator or a spore disperser. Consumption began in December and finished by mid February, and occurred before spore release, which happened later in Capelada than in Eume, probably influenced by differences in altitude. The consumer was identified as Apodemus sylvaticus by DNA analysis of its droppings and by capture of live animals. Throughout Galicia there was a significant increase in fern consumption rate as the population size of C. macrocarpa increased. Germination tests from droppings were carried out in 14 dishes but only in two dishes 1% and 0.3% of the spores germinated. Our results suggest that woodmouse can disperse spores of C. macrocarpa, although most of the spores were digested.     

国家Ⅰ级重点保护极危植物藤枣研究进展

国家Ⅰ级重点保护植物藤枣[Eleutharrhena macrocarpa(Diels)Forman]属防己科单种属植物,主要分布于云南南部地区。藤枣因其形态特征和分布式样在防己科植物中较为独特,具有重要的植物系统学和区系地理学研究价值。据相关文献记载,目前发现和记录的藤枣自然种群数量小于60株,种群处于极危状态,面临灭绝风险。国内外与藤枣相关的研究资料也相对匮乏。为及时拯救和关注这一濒危物种,该文在前贤研究的基础上,总结报道了藤枣的分类学简史、科学研究价值、自然种群数量、濒危状况、生物多样性保护地位、区系分布、模式标本认定等方面的最新研究进展,提出了近期的研究目标。期望能对藤枣的准确鉴定、精准调查和进一步深入研究提供基础信息和理论参考。     

Who can open the flower? Assessment of the flower opening force of mammal‐pollinated Mucuna macrocarpa

Effective pollinators in Fabaceae species with papillionaceous flowers should have sufficient force to open the petals and expose the stamens and pistils from the keel petals. Here, we assessed the force that is required (operative force) to open the petals of the mammal‐pollinated Mucuna macrocarpa, in parallel with estimating the force of bee species. The operative force of M. macrocarpa was quantified by a digital force gauge and the force of three bee species that frequent these flowers was estimated from body mass. The operative force was 1.635 ± 0.146 (mean ± SD) newton (N). This force was far larger than that estimated for the largest bee in the study area. In addition, the operative force of M. macrocarpa was 16–409 times greater than that of bee‐pollinated plants. Our results demonstrate that the operative force of M. macrocarpa flowers is adapted to mammalian openers, preventing potential nectar robbers.     

Boletus roseoflavus,a new species of Boletus in section Appendiculati from China

Boletus roseoflavus is described as a new species based on morphological and molecular studies of the type collection and additional materials. Boletus roseoflavus is morphologically distinct from other related species (B. regius, B. appendiculatus, and B. speciosus) by its light pink, pink, or rosy pileus, lemon yellow or golden yellow context, and lemon yellow or light yellow, enlarged download stipe with yellow reticulation. Phylogenetic analyses based on ribosomal DNA internal transcribed spacer regions and nuclear large subunit ribosomal RNA indicate that B. roseoflavus belongs to Boletus section Appendiculati.     

LEAF GAS EXCHANGE IN QUERCUS MACROCARPA (FAGACEAE): RAPID STOMATAL RESPONSES TO VARIABILITY IN SUNLIGHT IN A TREE GROWTH FORM

Responses in net photosynthesis (A), stomatal conductance to water vapor (g), and leaf xylem pressure potential (ψ) were measured in the deciduous tree Quercus macrocarpa during alternating periods of sun (photosynthetic photon flux, PPF > 1,500 μmol m^-2 sec^-1) and shade (ca. 350 μmol m^-2 sec^-1 simulating cloud cover). Measurements were made on trees growing at the gallery forest-prairie edge on the Konza Prairie Research Natural Area in northeast Kansas. The region is near the westernmost extension of the range of Q. macrocarpa where this species experiences significant seasonal water stress (minimum ψ < -2.9 MPa). Quercus macrocarpa was chosen for study because it has relatively high A (15 μmol m^-2 sec^-1) and g (300 mmol m^-2 sec^-1) in contrast to the deciduous and evergreen subalpine trees previously studied. Both trees and large saplings of Q. macrocarpa responded to alternating several minute periods of sun and shade with relatively rapid changes in A and g. Reductions in g (110 mmol m^-2 sec^-1) during shade periods lowered transpirational water losses (E) by 13% (and reduced A by 5%) relative to estimates of A and E made assuming g remained constant. Partial stomatal closure during shade was correlated with moderate enhancement in ψ (0.31 MPa) in Q. macrocarpa. However, greater increases in ψ were measured in adjacent prairie grasses exposed to similar periods of shade (0.72 MPa in Andropogon gerardii, 0.61 MPa in Sorghastrum nutans). Reduced variability in ψ in tree growth forms may reflect greater buffering of water relations associated with the large size of trees, the amount of tissue devoted to water storage, and differences in hydraulic resistance relative to herbs. Nonetheless, the gas exchange and water relations responses in Q. macrocarpa were much more similar to those previously measured in herbaceous subalpine and grassland species than to those documented for subalpine trees. Thus, rapid gas exchange responses to variable PPF may also occur in tree growth forms.     

Four new species of Entoloma s.l. (Agaricales) from southern China

Four new Entoloma s.l. species (E. azureosquamulosum, E. caeruleoflavum, E. hainanense, and E. subtenuicystidiatum) are described from southern China. E. azureosquamulosum fits well within the section Rhamphocystotae, E. caeruleoflavum belongs to the section Entoloma, E. hainanense is placed in the section Calliderma, and E. subtenuicystidiatum is a species in the section Cyanula. Preliminary phylogenetic analyses for the four new species are provided based on ITS and LSU sequences in this paper.     

First record of fossil angiosperm wood (Ulmoxylon,Ulmaceae) from the famous locality of Bı́lina (Czech Republic,Early Miocene)

A fossil angiosperm wood is described for the first time from the famous Early Miocene locality of Bı́lina. It represents a fossil elm wood, attributed to Ulmoxylon marchesonii Biondi. The fossil wood can be compared to extant North American soft elms, also to Ulmus macrocarpa Hance and U. parvifolia Jacq. from China or to the European common elm U. carpinifolia Gled. The wood together with fossil leaves/fruits of Ulmus pyramidalis Goeppert forms a single natural fossil species that lived in the Bı́lina area during the Early Miocene. The influence of two types of preservation, permineralised and xylitic, on the same wood species is also discussed. To cite this article: J. Sakala, C. R. Palevol 1 (2002) 161–166.     

Old World and New World Cupressus pollen: morphological and cytological remarks

The aim of this work was to collect new information about pollen morphology and pollen wall structure comparing Cupressus species from the Old World and New World. Cupressus is a nonmonophyletic genus that includes species that appear to be divided into Old World and New World clades. Observations in this study on cypress pollen indicate that grain size and composition of intine β-glucans are different between the considered Old World and New World species. Different from all the other American cypress species, pollen of C. macrocarpa reacted to dying in a similar manner to Old World species. Rehydrated pollen grains collected from 20 Asian, Afro-Mediterranean and American cypress species were measured under a light microscope. The size of the pollen grains and the percentage of intine in relation to the pollen grain diameter were significantly different between Old World and New World species. Pollen wall composition was tested after addition of different dyes to the hydration solution, and subsequent observations were carried out by light and fluorescence microscopy. Lugol and calcofluor staining showed differences in composition of the middle and inner intine layers between New World and Old World species.