珍稀药用植物白及光合与蒸腾生理生态及抗旱特性

以珍稀濒危药用植物白及(Bletilla striata)叶片为研究对象,应用Li-6400XT便携式光合仪分别在晴天和阴天进行光合生理生态特性研究。结果显示晴天Gs、Pn、Tr日变化呈现双峰型,阴天为单峰型;光合-蒸腾具有极显著线性正相关关系与良好的线性耦合关系(晴天和阴天的相关系数分别为0.883^**、0.954^**,回归直线斜率分别为2.38、3.78);PAR-Pn与PAR-Tr、Tl-Pn与Tl-Tr、Gs-Pn与Gs-Tr 的回归直线形态非常相似,除晴天Tl与Pn外,其余两两相关关系均达到了显著水平;PAR、Tl和Gs三个因子与Pn、Tr均表现为正相关关系,其中Gs是调控Pn与Tr的最主要因子。进行聚乙二醇6000(PEG6000) 渗透胁迫实验以评价白及抗旱能力,分析不同质量分数PEG6000(0、5、20、40、60g/L)下的白及幼苗叶绿素含量、叶片含水量、相对电导率3个生理指标,结果表明叶绿素含量与与胁迫浓度呈负相关(R²=0.7854),随着PEG质量分数的增加,叶片的叶绿素含量持续显著下降;叶片含水量与胁迫浓度呈负相关(R²=0.9936);相对电导率与与胁迫浓度呈正相关(R²=0.8755),相对电导率会随着PEG质量分数的增加而显著增加。试验结果综合分析显示白及为耐荫植物,抗旱能力不强。白及进行人工栽培应适当遮阴保持土壤与空气湿度。     

A reconsideration of Ada and the glumaceous brassias (Orchidaceae)

The genusAda (Orchidaceae: Oncidiinae) consists of eight species of epiphytes distributed from Nicaragua to Ecuador, Peru, and Venezuela. The two sections of the genusBrassia are compared, and the sectionGlumaceae is transferred toAda. Ada, the glumaceous brassias, andMesospinidium are compared, and it is suggested thatAda (in the broad sense) andMesospinidium are distinct but closely related genera.     

A new macrolide and six cycloartane triterpenoids from the tubers of Bletilla striata

A new 12-membered macrolide (1) along with two known C-31 and four known C-32 cycloartane triterpenoids (2–7) were isolated from the tubers of Bletilla striata. Their structures were determined by spectroscopic analysis, including 1D NMR, 2D NMR, and HRESIMS. The chemotaxonomic significance of these isolates, especially C-31 and C-32 cycloartane triterpenoids, are discussed. To our knowledge, this is the first report on the co-occurrence of the unusual 24-methyl, 24-ethyl, and 24,24-dimethyl cycloartane triterpenoids in the family Orchidaceae.     

ADDITIONS AND CORRECTIONS TO THE FOLIICOLOUS LICHEN FLORA OF COSTA RICA. THE FAMILY ARTHONIACEAE,WITH NOTES ON THE GENUSSTIRTONIA

The taxonomy of the foliicolous members of Arthoniaceae (Arthonia, Arthothelium, Cryptothecia, Ermothecella) in Costa Rica is revised.Cryptothecia farkasiaesp. nov. is described, being closely related toStirtonia sprucei, and bearing pycnidia reminiscent ofEremothecella. Arthonia lividofuscais placed in synonymy withA. aciniformis. Pycnidia and pycnospores are further described forArthonia leptosperma, A. cyanea, A. palmulacea, A. trilocularis, Arthothelium cingulatum, Stirtonia spruceiandS. macrocephala, and campylidia were found on thalli ofArthonia aciniformis. Arthonia nigratulaandCryptothecia candidaare reported for the first time from Costa Rica, and new localities are given for previously reported species. Ecological data are provided, and the relationships between foliicolous members of the Arthoniaceae are discussed.     

Reevaluation of the biological status of Juniperus Deppeana var. sperryi Correll

Foliage and bark samples were collected from the tree that provided the type specimen forJuniperus deppeana var.sperryi Correll, as well as from trees from populations ofJ. pinchotii Sudw.,J. flacida Schl., andJ. deppeana Steud. var.deppeana. These four taxa were compared using terpenoid and morphological characters. The terpenoid data suggest thatJ. deppeana var.sperryi is most closely related toJ. deppeana var.deppeana; no evidence of relict or present hybridization withJ. flaccida was detected. The morphological data showedJ. deppeana var.sperryi to be intermediate in several characters betweenJ. deppeana var.deppeana andJ. flacdda. The probability of a hybrid origin for this taxon is discussed. Due to the scattered occurrence of trees referable toJ. deppeana var.sperryi, it is proposed that this taxon be reduced in rank toJ. deppeana formasperryi.     

兰科药用植物活性多糖研究进展

兰科(Orchidaceae)是有花植物中第二大科,目前已确认的兰科植物有736属28 000种,其中有82属343种可作药用。常见的兰科药用植物有铁皮石斛、天麻、白及和金线莲等。兰科药用植物功效成分主要为糖类、茋类、酚类、萜类、生物碱类、黄酮类和甾醇等,其中主要由甘露糖和葡萄糖等单糖构成的水溶性多糖是其重要活性成分之一,具有增强免疫力、抗肿瘤、抗氧化、降血糖和改善记忆等多种药理功能。对兰科药用植物活性多糖的结构、药理作用和生物合成等方面的研究进展进行了综述,并提出今后需要重点研究的方向,为进一步推动兰科药用植物资源保护及合理开发利用提供参考。     

Decreased photosystem II activity facilitates acclimation to fluctuating light in the understory plant Paris polyphylla

In forests, understory plants are usually exposed to sunflecks on timescales of seconds or minutes. However, it is unclear how understory plants acclimate to fluctuating light. In this study, we compared chlorophyll fluorescence, PSI redox state and the electrochromic shift signal under fluctuating light between an understory plant Paris polyphylla (Liliaceae) and a light-demanding plant Bletilla striata (Orchidaceae). Within the first seconds after transition from low to high light, PSI was highly oxidized in P. polyphylla but was highly reduced in B. striata, although both species could not generate a sufficient trans-thylakoid proton gradient (ΔpH). Furthermore, the outflow of electrons from PSI to O₂ was not significant in P. polyphylla, as indicated by the P700 redox kinetics upon dark-to-light transition. Therefore, the different responses of PSI to fluctuating light between P. polyphylla and B. striata could not be explained by ΔpH formation or alternative electron transport. In contrast, upon a sudden transition from low to high light, electron flow from PSII was much lower in P. polyphylla than in B. striata, suggesting that the rapid oxidation of PSI in P. polyphylla was largely attributed to the lower PSII activity. We propose, for the first time, that down-regulation of PSII activity is an important strategy used by some understory angiosperms to cope with sunflecks.     

Low genetic diversity in marginal populations of Bletilla striata (Orchidaceae) in southern Korea: Insights into population history and implications for conservation

The warm-temperate vegetation of Korea, currently limited to southern coastal areas, shifted southward during the Last Glacial Maximum towards glacial refugia putatively located in southern Japan and/or southern China. We hypothesized two scenarios of post-glacial re-colonization of warm-temperate species: (i) that extant Korean populations originated from a single source or (ii) that they are derived from multiple source populations. To test which of these scenarios is more likely, we investigated the patterns of genetic diversity in 16 populations of the warm-temperate terrestrial orchid Bletilla striata, employing 20 allozyme loci. Levels of genetic variation in B. striata were substantially lower than those reported in most other terrestrial orchids. However, the degree of genetic differentiation among populations was moderate. These results suggest a pattern of post-glacial re-colonization fitting the first scenario. Both in situ and ex situ conservation strategies are suggested to preserve the genetic variation of B. striata in Korea.     

Taxonomy of the bouteloua repens complex

An investigation was made of grasses variously referred toBouteloua americana,B. filiformis, B. radicosa, B. repens, B. bromoides, B. heterostega, B. pubescens, andB. williamsii. Four of these species,B. americana, B. williamsii, B. repens, andB. radicosa, are maintained as separate taxa; the other four are reduced to synonymy underB. repens. Described as new isB. longiseta, with a tropical distribution from Oaxaca, Mexico, south to Honduras. Chromosome counts of 2n = 20 forB. williamsii and 2n = 40 forB. longiseta are the first for these taxa. Counts of 2n = 20, 2n = 40, and 2n = 60, and a few aneuploid numbers, are reported forB. repens     

Notes on Bletia (Orchidaceae)

New species ofBletia from Mexico are described and illustrated:B. concolor, B. similis, andB. urbana. The identity ofB. campanulata Llave & Lex. is discussed, andB. reflexa Lindl. is considered to be a distinct species. Several South American epithets are treated as synonyms ofB. campanulata. A key to the recognized species ofBletia is given.     

A MOLECULAR APPROACH TO THE CIRCUMSCRIPTION AND EVALUATION OF SOME GENERA SEGREGATED FROMPARMELIAS. LAT.

New sequences have been produced of the ITS rDNA region of twenty-nine species ofParmeliaceae, and analysed by neighbour-joining maximum likelihood distance analysis, and maximum parsimony analysis. Twelve monophyletic groups have been identified, most of which correspond to proposed generic segregated fromParmelias. lat.ParmeliaandParmelina,Melanelia, andPuncteliaappear as independent monophyletic groups; the type species of the two latter genera were, however, not included in the analysis. The parsimony analysis does not supportXanthoparmeliaas a monophyletic group separate fromNeofuscelia, andRimelia reticulatais nested withinParmotrema. Parmelinopsis horrescensis more closely related toHypotrachyna revolutathan toParmelina. Genetic distance values suggest thatFlavoparmelia caperatais closer toParmotremathan to other taxa included, and thatPlatismatia glaucaandHypogymnia tubulosaare closer toParmelias. lat. than to thePhysciaceae. However, there is no conclusive support for any of the latter groupings in the parsimony analysis. We conclude that the ITS region contains valuable information for studying generic delimitations within the familyParmeliaceae, but our study suggests that this region will not conclusively resolve within-family relationships in this group.     

Taxonomy of barkeria (Orchidaceae)

The genusBarkeria (Orchidaceae) consists of four species and eight subspecies (the treatment includes a key) of epiphytic plants endemic to Mexico and Central America.Barkeria is separated from the genusEpidendrum on the structure of the rostellum and column in the flower, plus shape of the pseudobulbs. The authors suggest thatBarkeria is most closely related toCaularthron based on the general shape of the flowers, widely spreading fleshy column wings, and structure of the rostellum.     

Antimicrobial agents from Bletilla striata

Three new bibenzyls and two new dihydrophenanthrenes, which exhibit antimicrobial activity, were isolated from tubers of Bletilla striata. They were identified by various spectroscopic methods.     

Vicia johannis and wild relatives of the faba bean: a taxonomic study

Preliminary taxonomic and agronomic investigation was made of close relatives of the faba bean (Vicia faba) to aid future plant breeding. Cluster analysis of 2 yr’s morphometric data showed thatV. johannis is clearly separable from other members of theV. narbonensis complex. AlsoV. faba was much more distinct from eitherV. narbonensis orV. johannis than they are from each other. Petal colours at anthesis provided a rapid method of field identification forV. faba, V. narbonensis, andV. johannis. The 2 varieties ofV. johannis can also be distinguished by their petal colours: var. procumbens shows a marked colour change at anthesis and var. johannis does not. The geographical distribution of the plant material studied suggests thatV. johannis is found in Turkey and Europe despite being omitted from the major published floras. BothV. johannis andV. narbonensis possess agronomically useful characters of importance to faba bean breeders, including increased frost tolerance and resistance to bothAphis fabae andBotrytis fabae.     

Genetic analysis and molecular mapping of a wheat gene conferring tolerance to the greenbug (<Emphasis Type="Italic">Schizaphis graminum</Emphasis> Rondani)

The greenbug, Schizaphis graminum (Rondani), is one of the major pests of wheat worldwide. The efficient utilization of wheat genes expressing resistance to greenbug infestation is highly dependent on a clear understanding of their relationships. The use of such genes will be further facilitated through the use of molecular markers linked to resistance genes. The present study involved several F₂ wheat populations derived from crosses between susceptible cultivars and resistant germplasm carrying different greenbug resistance genes. These populations were used to characterize the inheritance of a wheat gene (Gbz) conferring tolerance to greenbug biotype I, to identify molecular markers linked to Gbz, and to investigate the relationship between Gbz and Gb3, a previously identified greenbug resistance gene. Our results indicated that Gbz is inherited as a single dominant gene. Microsatellite marker Xwmc157 is completely linked to Gbz, and Xbarc53 and Xgdm46 flank Gbz at distances of 5.1 and 9.5 cM, respectively. Selection of Gbz using marker Xwmc157 alone gives breeders 100% selection accuracy. Gbz may be placed in the distal region of the long arm of the wheat chromosome 7D. The results of allelism tests indicated that Gbz is either allelic or tightly linked to Gb3.Communicated by D.A. Hoisington     

Tillandsia carminea — eine interessante neue Bromeliacee aus dem Orgelgebirge bei Rio de Janeiro (Brasilien)

Tillandsia carminea is a new, morphologically and ecologically distinct species, related toT. stricta Solander, which occurs in the Serra dos Orgaos near Teresopolis, Brazil. It has been taken forT. rosea Lindley, but new investigations have shown thatT. rosea is a synonym toT. stricta and thatT. carminea is a good and distinct species.

     

Variation and taxonomy of Betula uber,B. Lenta,and B. alleghaniensis

Morphological variation was analyzed in the endangeredBetula uber and sympatric dark-barked tree birches,B. lenta andB. alleghaniensis, to determine the extent of differences among the three taxa. Univariate and multivariate analyses of leaf and fruit characters indicated that the three taxa are morphologically distinct, thatB. uber is more similar toB. lenta than toB. alleghaniensis, that intermediates betweenB. uber andB. lenta do not occur, and that leaves are necessary for absolute separation ofB. uber fromB. lenta because of overlap of fruit characters. Field observations of the bark indicate no differences betweenB. uber andB. lenta while those of growth form suggest thatB. uber may have a more compact crown thanB. lenta. The evidence presented here supports an alliance ofB. uber with the dark-barked tree birches (seriesCostatae).     

Phylogenetic relationships in theCampanulales based onrbcL sequences

Phylogenetic relationships within the angiosperm orderCampanulales were investigated by comparative sequencing of the chloroplast generbcL. CompleterbcL sequences were obtained for ten species in six families within the order. These data were analyzed along with previously publishedrbcL sequences from other taxa (for a total of 117 species) within the subclassAsteridae and outgroups, producing 32 equally parsimonious trees. A subset consisting of 44 of these taxa was then chosen and more rigorous analyses performed, resulting in four equally parsimonious trees. Results indicate that two major clades roughly corresponding to traditionally circumscribedAsterales andCampanulales exist as sister taxa. In particular, therbcL trees indicate thatSphenoclea is not a member ofCampanulales orAsterales, thatPentaphragma is more closely allied toAsterales thanCampanulales, that theCyphiaceae are not monophyletic, thatCampanulaceae andLobeliaceae are not sister taxa, and thatStylidiaceae are correctly placed withinCampanulales.