珍稀水生植物——宽叶泽苔草的核型研究

宽叶泽苔草（Caldesia granis Samuel）。是一种珍稀濒危水生植物。它曾经一度被认为已经从中国大陆灭绝,但最近又在湖南省的一个高山沼泽中被发现。本文首次报道了依据上述新发现地点的宽叶泽苔草材料进行的细胞学研究结果。核型分析结果表明：本种染色体数目为22,其染色体组型高度不对称。结合前人对宽叶泽苔草一些近缘种的细胞学及古生物学研究结果,作者认为泽苔草属植物很可能是泽泻科中最进化的一个属。     

湖南植物志资料（二）：石竹科,壳斗科,伞形科,茜草科,菊科,泽泻科补遗

湖南植物新记录区计１０种,隶属于６科８属,泽苔草属为新记录;沼生繁缕,大苗山柯,白毛青冈,肾叶天胡荽,金草,剑叶耳草,多花茜草,秃果华千里光,崇澍华千里光,宽叶泽苔草为新记录种。     

Phylogenetic relationships in Alisma (Alismataceae) based on RAPDs, and sequence data from ITS and trnL

The phylogeny of Alisma (Alismataceae), a genus of approximately nine species of aquatic plants mainly distributed in the Northern Hemisphere, was reconstructed with parsimony analysis on RAPD data and sequences of the nuclear ITS and chloroplast trnL regions, and with MDS on RAPD data. Separate analyses were performed on each data set. Butomus umbellatus was used as outgroup in the analysis of sequence data, and Luronium and Baldellia in the analyses of RAPD data. Among diploid Alisma, two major groups were found: (i) the gramineum group consisting of A. gramineum and A. wahlenbergii, and (ii) the plantago-aquatica group with A. plantago-aquatica, A. orientale, A. subcordatum, A. juzepczukii and A. ``bottnicum'. Taxa within the groups were poorly separated. The Baltic endemics A. wahlenbergii, A. juzepczukii and A. ``bottnicum' have probably originated relatively recently from local populations of A. gramineum (i.e. A. wahlenbergii) and A. plantago-aquatica (i.e. A. juzepczukii and A. ``bottnicum'). The exact origin of the polyploid taxa, i.e. A. lanceolatum, A. triviale, A. canaliculatum and A. rariflorum, is still unclear.     

The interaction between Plectosporium alismatis and sublethal doses of bensulfuron-methyl reduces the growth of starfruit (Damasonium minus) in rice

Plectosporium alismatis is a fungal pathogen that is being investigated as a biocontrol agent for suppressing starfruit (Damasonium minus), a significant weed of Australian rice fields. The aim of this research was to study the effect of the fungus on weed competition and its interactions with chemical herbicides. Conidial germination was significantly reduced by Londax® (bensulfuron-methyl), while MCPA had no effects. Glasshouse trials showed evidence of synergism between the fungus and 1.56% of the recommended dose of Londax®, in reducing the weed growth. The application of inoculum (conidia suspended in water) in the glasshouse eliminated weed competition with rice. In the field, the reduction in weed growth caused by the fungus did not significantly eliminate starfruit competition with rice. This is thought to be due to the presence of other weeds.     

Population genetics of two rare perennials in isolated wetlands: Sagittaria isoetiformis and S. teres (Alismataceae)

We investigated genetic structure in two closely related perennial plants that occur in isolated wetlands: Sagittaria isoetiformis, restricted to the southeastern Coastal Plain of North America, and S. teres, endemic to the northeastern Coastal Plain. Using horizontal starch-gel electrophoresis, we screened 527 individuals from 11 populations of S. isoetiformis and 367 individuals from seven populations of S. teres. A high proportion of the 16 loci were polymorphic (%P(S) = 93.8% in S. isoetiformis and %P(S) = 75.0% in S. teres), with higher mean numbers of alleles per polymorphic locus and effective alleles per locus in S. isoetiformis (AP = 3.27, A(E) = 1.90) than in S. teres (AP = 2.58, A(E) = 1.30). Species- and population-level expected heterozygosities were higher in S. isoetiformis (H(ES) = 0.399, H(EP) = 0.218) than in S. teres (H(ES) = 0.177, H(EP) = 0.101). Jackknife estimates of F statistics indicated moderate levels of inbreeding in S. teres (F(IS) = 23.1%). Strong differentiation characterized these geographically isolated populations (G(ST) = 39.9% in S. isoetiformis, and G(ST) = 26.1% in S. teres). Genetic identities varied substantially within (ī = 75%, range = 0.558-0.963 in S. isoetiformis; ī = 89%, range = 0.776-0.963 in S. teres) and among species (ī = 81%, range = 0.506-0.882), leading to the discrimination of four regional population clusters using nonmetric multidimensional scaling (NMDS). It appears that S. isoetiformis and S. teres are a progenitor-derivative species pair.     

中国特有植物——腾冲慈姑(Sagittaria tengtsungensis H. Li)的核型研究

慈姑属 ( Sagittaria L.)是泽泻科 ( Alismataceae)中一个很重要的属 ,世界广布 ,共约30个种 ,数量仅次于美洲分布的刺果泽泻属 ( Echinodorus Rich.) (约 4 7种 ) [1 ] 。慈姑属植物在我国已知有 8种、1亚种、3变种及 1变型 ,共 1 1个分类群 ,其中特有种 4个 ,对于研究全世界的慈姑属植物来说 ,中国地区有着重要意义 [2 ]。腾冲慈姑为我国慈姑属植物的一个特有种 ,仅分布于我国云南西部的山地沼泽中[3] 。陈家宽 ( 1 989)曾对中国 7种慈姑属植物的核型进行了研究 ,但由于受到材料来源的限制 ,未报道腾冲慈姑的核型。本文首次对腾冲慈姑的…     

Guaiane-type sesquiterpenoids from Alisma orientalis

Two guaiane-type sesquiterpenoids named orientalol E (1) and orientalol F (3) were isolated from the rhizome of Alisma orientalis (SAM) JUZEP together with two known guaiane-type sesquiterpenoids alismol (2) and alismoxide (4). Their relative stereostructures were elucidated by spectroscopic methods, whereas absolute stereostructures were determined on the basis of chemical correlation.