Development of Floral Apex After Floral Induction in Stylo (Stylosanthes guianensis (Aubl.) Sw. var. guianensis)

The apex morphology of stylo (Stylosanthes guianensis var. guianensis)is described in four developmental phases (vegetative, transitional,initiated and floral) further subdivided into a total of tenstages. The apical dome broadens and flattens as induction proceedsuntil the initiation phase when apical diameter within 0.05mm of the dome apex is 55 per cent greater than in the vegetativeapex. Changes in vegetative morphology during induction aredescribed. Stylosanthes guianensis var. guianensis, stylo, flowering, reproductive anatomy, developmental stages     

Tree-ring element analysis of Korean pine (Pinus koraiensis Sieb. et Zucc.) and Mongolian oak (Quercus mongolica Fisch. ex Turcz.) from Changbai Mountain,north-east China

Summary Tree-ring analysis of 17 elements (Pb, Cd, Cu, Zn, As, Cr, Ti, Ni, V, Mn, Fe, Al, Ca, Mg, K, Na and P) was performed on Korean pine (Pinus koraiensis Sieb. et Zucc.) and Mongolian oak (Quercus mongolica Fisch. ex Turcz.) specimens from Changbai Mountain, a remote nature reserve in north-east China. The radial distribution patterns of Pb, Cu, Cr, Ti, Ni, V, As and Fe for both Korean pine and Mongolian oak were similar: concentrations remained generally constant in tree-ring intervals spanning approximately 200 years. These temporal patterns were in accordance with the known stability of the local ecological environment during this period. However, the other elements showed characteristic distribution patterns that differed between Korean pine and Mongolian oak. These patterns can only be interpreted in terms of physiological results; specifically they appeared to be related to the sapwood-heartwood conversion.     

苍术（Atractybeslancea（Thunb．）DC．）种内遗传多样性分析

分析了苍术（Ａｔｒａｃｔｙｌｏｄｅｓｌａｎｄｅａ（Ｔｈｕｎｂ．）ＤＣ．）５种等位酶（ＭＤＨ,ＧＤＨ,ＰＰＯ,ＳＯＤ,ＰＥＲ）１２个位点上２５个等位基因的分化特征。结果表明：群体内多态位点比例平均为０．６１,每个位点的平均杂合率为０．２６,每个位点发现的平均等位基因数为１．７８。苍术种内基因多样性的８６％产生在群体内,群体间分化的明显效果为１４％。所有配对组合,群体间的平均遗传距离是０．１１,遗传同一性是０．９０。说明苍术种内变异很大。同时探讨茅苍术的分类位置,认为茅苍术不是苍术和白术的杂交种。     

Changes in Oregon white oak (Quercus garryana Dougl. ex Hook.) following release from overtopping conifers

Oregon white oak or Garry oak (Quercus garryana Dougl. ex Hook.) is a shade-intolerant, deciduous species that has been overtopped by conifers during the past century in parts of its range due to an altered disturbance regime. We examined the response of suppressed Oregon white oak trees in western Washington, USA, to three levels of release from overtopping Douglas-fir (Pseudotsuga menziesii [Mirb.] Franco). We treated individual oak trees with either full release from competition, partial (“half”) release from competition, or a stand-level thinning of Douglas-fir not directed toward release (control). Five years after treatment, oak trees had suffered no mortality or windthrow. Stem diameter growth was 194% greater in the full-release treatment relative to the control. Acorn production varied widely by year, but in years of higher production, acorn production was significantly greater in both release treatments than in the control. Frequency of epicormic branch formation was significantly increased for years 1 and 2 by the full release; the greatest response occurred between 2 and 6 m above ground level. The greatest number of epicormic branches formed on trees on which the majority of original limbs had died back prior to treatment. Trees with relatively less crown dieback at the time of treatment generally had greater stem growth and acorn production responses to release treatments. Our findings indicate that these released Oregon white oak trees are beginning to recover after an extended period of suppression.     

Comparison of two cysteine endopeptidases from Pseudananas macrodontes (Morr.) Harms (Bromeliaceae)

The properties of two cysteine peptidases (macrodontain I and II) isolated from fruits of Pseudananas macrodontes have been compared. The enzymes showed optimum pH ranges near neutrality and were inhibited by E-64 and other cysteine peptidase inhibitors. Molecular masses were 23459 and 23703 kDa, the isoelectric points were 6.1 and 5.9, and the Km values were 13.4 and 8.9 microM (Bz-Phe-Val-Arg-AMC) for macrodontain I and II, respectively. N-alpha-CBZ-L-amino acid p-nitrophenyl esters were tested for both enzymes. The N-terminal sequences of both proteases differed slightly and showed high sequence similarity to other pineapple stem-derived cysteine endopeptidases.     

Phylogeny and biogeography of Aralia sect. Aralia (Araliaceae)

Aralia sect. Aralia (Araliaceae) consists of approximately eight species disjunctly distributed in Asia and North America. Phylogenetic and biogeographic analyses were conducted using sequences of the internal transcribed spacer regions of the nuclear ribosomal DNA. Aralia racemosa from eastern North America was sister to A. californica from western North America. Aralia cordata from eastern Asia did not form a species-pair relationship with the eastern North American A. racemosa. The two subspecies of A. racemosa formed a monophyletic group. Biogeographic analyses showed a close area relationship between eastern North America and western North America. The Himalayas were cladistically basal and eastern Asia was placed between the Himalayas and North America. The biogeographic analysis supported the origin of the eastern Asian and eastern North American disjunct pattern in Aralia sect. Aralia via the Bering land bridges. Comparisons with results of phylogenetic analyses of other genera suggested that (1) the floristic connection between eastern North America and western North America may be stronger than previously thought; and (2) the biogeographic patterns in the Northern Hemisphere are complex. Furthermore, a lack of correlation between sequence divergence values and phylogenetic positions was observed, suggesting the importance of a phylogenetic framework in biogeographic analyses.     

Chemical constituents from Schefflera leucantha R.Vig. (Araliaceae)

Processive phytochemistry and pharmacological investigation of Schefflera leucantha R.Vig. (Araliaceae) led to the isolation of fifteen known compounds: a nucleobase (1), six small aromatic molecules (2–7), three phenylpropanoids (8–10), four lignans (11–14) and a fatty acid derivative (15). Spectroscopic methods were used to establish the structure and configuration of isolates, followed by their unambiguous confirmation with literature data. We report for the first time (to the best of our knowledge), the isolation of β-amino-3-methoxy-4-hydroxybenzene-ethanol (4) from a natural source. Furthermore, compounds 1, 5, 9–15 are being reported from Araliaceae family for the first time, whereas compounds 2, 3, 6–8 from the genus Schefflera for the first time. The biological screening results show that compounds 9 and 10 induce a moderate inhibitory effect on aldose reductase, while compounds 3, 5, and 8 display significantly high neuroprotective activities.     

Floral and reproductive biology of Drosophyllum lusitanicum (L.) Link (Droseraceae)

We studied the floral and reproductive biology of Drosophyllym lusitanicum (Droseraceae), a species endemic to the western Iberian Peninsula and northwest Morocco. Flowering lasted from March to August, peaking in April. The species is clearly homogamous, with pollen germination and stigma receptivity occurring even in preanthesis. This was reflected in the high rates of fruit set and seed set in bagged inflorescences. Fructification did not differ significantly between different pollination treatments, although we did find differences between some treatments in the numbers of viable seeds per flower and fruit. However, seed weight did not differ significantly. The importance of self-pollination over cross-pollination was also supported by the low percentages of fructification (24.67%) after emasculation and open pollination. Metameric deviations were seen in flowers, although this abnormality was not translated as any reproductive benefit or disadvantage (fructification, number or weight of seeds) in comparison with normal flowers.     

Sex-Biased Temporal Gene Expression in Male and Female Floral Buds of Seabuckthorn (Hippophae rhamnoides)

Seabuckthorn is an economically important dioecious plant in which mechanism of sex determination is unknown. The study was conducted to identify seabuckthorn homologous genes involved in floral development which may have role in sex determination. Forty four putative Genes involved in sex determination (GISD) reported in model plants were shortlisted from literature survey, and twenty nine seabuckthorn homologous sequences were identified from available seabuckthorn genomic resources. Of these, 21 genes were found to differentially express in either male or female flower bud stages. HrCRY2 was significantly expressed in female flower buds only while HrCO had significant expression in male flowers only. Among the three male and female floral development stages (FDS), male stage II had significant expression of most of the GISD. Information on these sex-specific expressed genes will help in elucidating sex determination mechanism in seabuckthorn.     

Molecular systematics and genetic differentiation of Pinus sylvestris (L.) and P. densiflora (Sieb. et Zucc.)

Summary Allozyme variation was examined in 22 populations of Pinus densiflora (Sieb, et Zucc.) and four geographic varieties of P. sylvestris (L.): var lapponica (Fries, Hartman), var armena (Komarov), var mongolica (Litvinov) and var sylvestriformis (Takenouchi). In addition, we developed paternal chloroplast (cp) DNA markers that distinguish P. densiflora from var lapponica, var armena and var mongolica. UPGMA cluster analysis based on Nei's distances between all pairwise combinations of the 22 populations revealed patterns corresponding strictly to geographic origin and taxonomic status. Analysis of allozyme variation in var lapponica, var armena and var mongolica demonstrated a high level of intrapopulational variability but a low level of interpopulational differentiation. It appears that the late Pleistocene blending of genetically diverse populations was responsible for the observed variation patterns. The constructed phylogenetic trees also showed late divergence of these three varieties. The var sylvestri formis was genetically distinct from the other three P. sylvestris varieties. The genetic distances separating var sylvestriformis from P. densiflora and the other taxa lend support to a separate taxonomic status for var sylvestriformis and a close relation with P. densiflora. We found that var sylvestriformis harbors admixtures of allozymes and cpDNA from both P. sylvestris and P. densiflora, which suggests an introgressive nature of this variety. Levels of intrapopulational variability were similar in P. sylvestris and P. densiflora, but interpopulational differentiation was much higher in P. densiflora. In the constructed phylogenetic trees, populations of this species were characterized by relatively long internode distances and branch lengths. The present results suggest that P. densiflora has a more advanced evolutionary age than P. sylvestris.     

Floral trimorphism and monomorphism in continental and island populations of Eichhornia paniculata (Spreng.) Solms. (Pontederiaceae)

Eichhornia paniculata (Spreng.) Solms. (Pontederiaceae) is a short-lived perennial or annual of marshes, seasonal pools and ditches of lowland tropical South America, primarily NE Brazil, and the Caribbean islands of Cuba and Jamaica. Comparisons, made under uniform glasshouse conditions, of populations originating from seed collected in the two regions revealed striking differences in their floral biology and breeding systems. The majority of populations sampled in NE Brazil are tristylous. Floral trimorphism is associated with pollen trimorphism and minor differences in anther size and pollen production among the three stamen levels. Unlike the majority of heterostylous plants the floral morphs of E. paniculata are highly self-fertile. Populations sampled on the island of Jamaica are composed exclusively of self-pollinating, semi-homostylous, mid-styled forms. Flowers from these populations are smaller and less showy, with reduced pollen heteromorphism and significantly fewer pollen grains and ovules per flower, in comparison with trimorphic populations from Brazil. Individual genotypes from Jamaican populations display considerable developmental instability in floral expression, particularly with respect to filament elongation of the lower stamen level. It is proposed that self-pollinating populations of E. paniculata are evolutionarily derived from tristylous ancestors and that the shift in breeding system is favoured at low density, following population bottlenecks, where pollinator service is unreliable.     

Macrocoma (Hornsch. ex C. Muell.) Grout (Orthotrichaceae)-a taxon new to India

Abstract

Desmatodon bogosicus C.Muell. hal. (1872) is shown to provide an earlier name for the recently described Tortula khartoumensis Pettet (1967). A new record of the species is supplied, from northern Kenya, and its generic position discussed.     

Phytotoxicity of extracts and fractions of Ouratea spectabilis (Mart. ex Engl.) Engl. (Ochnaceae)

Among the numerous plant species occurring in the Cerrado, Ouratea spectabilis stands out because of the lack of species that grow beneath its canopy. Therefore, this study aimed to evaluate the phytotoxic potential of different extracts and fractions of the hydroethanolic extract from leaves of O. spectabilis through laboratory bioassays of the pre-and post-emergence of seeds of Lactuca sativa L., determination of the mitotic index in root cells of Allium cepa L., antioxidant activity and phytochemical screening of different classes present in extracts and ethyl acetate fractions. It was possible to verify that different extracts and ethyl acetate fractions of O. spectabilis interfered with germination rates, as reduced germination was observed when compared with the control. Similarly, growth and development was affected in lettuce seedlings, as shown by the reduced length of primary roots and hypocotyls compared with the control. In addition, the mitotic index was reduced in treated groups compared with the negative control. HPLC-PAD analysis for both the hydroethanolic extract and its ethyl acetate fraction, showed a predominance of flavonoid compounds belonging to the groups of isoflavones and catechins in ethyl acetate fractions of hydroethanolic extracts. Thus, it was concluded that this species synthesizes phytotoxic compounds capable of interfering in the stabilization and development of other species.