Intraspecific Variation in Chemical Attraction of Rice to Insect Predators

The olfactory response of predators of the brown planthopper,Nilaparvata lugensStål, to different genotypes of rice (14 cultivars and breeding lines ofOryza sativaL. and 1 wild species,Oryza nivaraSharma et Shastry) was measured in an airflow olfactometer. Odor from rice plants attracted more females of the mirid predatorCyrtorhinus lividipennisReuter than plain air (control) on only 6 of the 15 rice genotypes. Orientation ofC. lividipennistoward volatiles of certain rice genotypes was apparent even when the plants were free of the brown planthopper. However, the predator distinguished between prey-infested and uninfested plants and preferred plants with eggs over plants with nymphs. The predator did not distinguish different stages of plant growth (vegetative, booting, or flowering). Plants artificially injured to simulate brown planthopper oviposition wounds were not as attractive to the predator as plants on which the planthopper had oviposited. The preassay preconditioning on the cultivar TN1 did not produce a predator bias for this genotype. This suggests that rearing effects or chemically mediated associative learning reported for some natural enemies did not influenceC. lividipennis'host response. Results with another predator, the coccinellidMicraspis hirashimaiSasaji, produced less consistent behavior. Planthopper-infested plants attracted more females ofM. hirashimaithan unifested plants in only 1 of the 12 rice genotypes evaluated. Implications for augmenting predators by rice cultivar selection and modification are discussed.     

“HAIRY CANOLA” – Arabidopsis GL3 Induces a Dense Covering of Trichomes on Brassica napus Seedlings

Transformation with the Arabidopsis bHLH gene 35S:GLABRA3 (GL3) produced novel B. napus plants with an extremely dense coverage of trichomes on seedling tissues (stems and young leaves). In contrast, trichomes were strongly induced in seedling stems and moderately induced in leaves of a hairy, purple phenotype transformed with a 2.2 kb allele of the maize anthocyanin regulator LEAF COLOUR (Lc), but only weakly induced by BOOSTER (B-Peru), the maize Lc 2.4 kb allele, or the Arabidopsis trichome MYB gene GLABRA1 (GL1). B. napus plants containing only the GL3 transgene had a greater proportion of trichomes on the adaxial leaf surface, whereas all other plant types had a greater proportion on the abaxial surface. Progeny of crosses between GL3⁺ and GL1⁺ plants resulted in trichome densities intermediate between a single-insertion GL3⁺ plant and a double-insertion GL3⁺ plant. None of the transformations stimulated trichomes on Brassica cotyledons or on non-seedling tissues. A small portion of bHLH gene-induced trichomes had a swollen terminal structure. The results suggest that trichome development in B. napus may be regulated differently from Arabidopsis. They also imply that insertion of GL3 into Brassica species under a tissue-specific promoter has strong potential for developing insect-resistant crop plants. Electronic Supplementary Material Supplementary material is available for this article at and is accessible for authorized users.     

降水对鄂尔多斯高原克隆植物分布的影响

鄂尔多斯高原地处半干旱区到干旱区的过渡带。通过沿鄂尔多斯高原从东到西的天然降水梯度的样带调查,分析了克隆植物的分布特征与降水的关系。结果表明:克隆植物的物种数量、占物种总数的比例和重要值以及根状茎型克隆植物的物种数量均与降水量呈显著正相关。5种优势植物克氏针茅、本氏针茅、黑沙蒿、赖草和短花针茅均为克隆植物,它们的分布也受降水影响。克氏针茅的密度、本氏针茅的盖度和密度、黑沙蒿的高度、盖度和密度以及赖草的高度均与降水量呈显著正相关。然而,赖草的盖度以及短花针茅的高度、盖度和密度均与降水量成负相关。因此,克隆植物在鄂尔多斯高原植被中具有重要作用,而且其作用随着降水量的增加而加强。     

中国大陆菊科二新归化植物

报道了中国菊科2新归化植物:短舌花金钮扣(Acmella brachyglossa Cass.)和粉黄缨绒花(Emilia praetermissa Milne-Redh.)。短舌花金钮扣原产美洲中部和南部以及加勒比海,我国台湾有逸生,最近在广州黄埔区发现1归化居群,而此前浙江象山县报道的本种新记录实为白花金钮扣[A. radicans var. debilis (Kunth) R. K. Jansen]的错误鉴定。粉黄缨绒花原产于西非,我国台湾有逸生,最近在广州市和鹤山市发现了大量的归化居群,而且生长旺盛并排斥其他草本植物,具有明显的入侵性,应引起相关部门的重视。凭证标本保存在中国科学院华南植物园标本馆(IBSC)。     

Relative host plant species use by the lantana biological control agent Aconophora compressa (Membracidae) across its native and introduced ranges

Aconophora compressa Walker (Hemiptera: Membracidae) was released in 1995 against the weed lantana in Australia, and is now found on multiple host plant species. The intensity and regularity at which A. compressa uses different host species was quantified in its introduced Australian range and also its native Mexican range. In Australia, host plants fell into three statistically defined categories, as indicated by the relative rates and intensities at which they were used in the field. Fiddlewood (Citharexylum spinosum L.: Verbenaceae) was used much more regularly and at higher densities than any other host sampled, and alone made up the first group. The second group, lantana (Lantana camara L.: Verbenaceae; pink variety) and geisha girl (Duranta erecta L.: Verbenaceae), were used less regularly and at much lower densities than fiddlewood. The third group, Sheena’s gold (another variety of D. erecta), jacaranda (Jacaranda mimosifolia D. Don: Bignoniaceae) and myoporum (Myoporum acuminatum R. Br.: Myoporaceae), were used infrequently and at even lower densities. In Mexico, the insect was found at relatively low densities on all hosts relative to those in Australia. Densities were highest on L. urticifolia, D. erecta and Tecoma stans (L.) Juss. ex Kunth (Bignoniaceae), which were used at similar rates to one another. It was found also on a few other verbenaceous and non-verbenaceous host species but at even lower densities. The relative rate at which Citharexylum spp. and L. urticifolia were used could not be assessed in Mexico because A. compressa was found on only one plant of each species in areas where these host species co-occurred. The low rate at which A. compressa occurred on fiddlewood in Mexico is likely to be an artefact of the short-term nature of the surveys or differences in the suites of Citharexylum and Lantana species available there. These results provide further incentive to insist on structured and quantified surveys of non-target host use in the native range of potential biological control agents prior to host testing studies in quarantine.     

The effects of host plant on the coccinellid functional response: Is the conifer specialist Aphidecta obliterata (L.) (Coleoptera: Coccinellidae) better adapted to spruce than the generalist Adalia bipunctata (L.) (Coleoptera: Coccinellidae)?

Female Aphidecta obliterata consumed an average of 26.6 ± 5.8 Elatobium abietinum and males consumed an average of 19.9 ± 3.2 Elatobium abietinum, but there was no significant difference in the number consumed between the sexes. In Petri dish trials, the larval stages of A. obliterata and all stages of Adalia bipunctata appeared to exhibit a Type II response to prey density, although A. obliterata adults showed a more linear response to prey density. There was no significant difference between the functional responses of the 3rd instars of the two coccinellid species, but there was a significant difference between the responses shown by the 1st instars, with A. obliterata larvae consuming more than those of A. bipunctata, especially at low densities, suggesting that the two species respond differently to an increase in prey density.At low prey densities, adults and 4th instars of both species exhibited a similar response to an increase in prey density but at higher densities the 4th instars and adult stages of A. bipunctata showed higher attack rates when compared with the same stages of A. obliterata.Adult and 4th instar A. obliterata exhibited Type II functional responses on spruce sections. The 4th instar A. obliterata larva appeared to be a more effective predator than the adult of the species, and was more effective when compared with adult A. bipunctata at lower prey densities but A. bipunctata adults appeared to be a more effective predator at higher prey densities.The host plant affected the rate of consumption by adult A. obliterata as adults on Sitka spruce sections consumed significantly higher numbers of aphids than their counterparts on Norway spruce. This was most noticeable at densities above 16 aphids.The distributions of the two coccinellid species in the olfactometer were significantly affected by the presence of host plant material. Aphidecta obliterata adults were found in significantly higher numbers in the Sitka spruce chambers than the control chambers (those without plant material). Adalia bipunctata adults were found in significantly lower numbers in the Norway spruce chamber than the control chamber.Although A. bipunctata has a higher level of voracity than A. obliterata, the latter is more adapted to the spruce environment and the boom and bust population dynamics of E. abietinum.     

柽柳根际一株盐单胞菌Bachu 26的分离、鉴定及其盐胁迫下的促生作用研究

盐渍化是世界性的土壤问题,植物促生根际细菌(plant growth-promoting rhizobacteria,PGPR)在盐碱地改良和促进植物生长方面具有独特优势。柽柳是典型的盐生植物,筛选其根际微生物并研究其促生效果与促生机制,以此开发微生物菌肥,具有重要的应用价值。【目的】筛选耐盐碱植物柽柳的根际微生物,对其基本特性、耐盐碱能力、促生功能及促生效果进行评估。【方法】从新疆巴楚境内野生柽柳根际土壤中筛选出一株耐盐碱细菌菌株Bachu 26;通过形态学观察、生理生化特性测定和16S rRNA基因序列分析,对该菌株进行鉴定;利用不同盐浓度(0%–20%)和不同pH(7.0–13.0),对菌株Bachu 26的耐盐耐碱能力进行测定;采用多种功能鉴定培养基测定其促生功能,并对生长素吲哚乙酸(indole-3-acetic acid, IAA)进行定量测定;通过二分格培养皿实验验证菌株产生挥发性酸性物质的能力;在普通培养皿上将拟南芥幼苗与菌株Bachu 26共培养,分析菌株对拟南芥幼苗的促生作用;在二分格培养皿上将拟南芥与Bachu 26隔离培养,分析菌株产生的挥发性酸性物质对拟南芥幼...     

Production of transgenic lily plants by<Emphasis Type="Italic"> Agrobacterium</Emphasis>-mediated transformation

A system for the production of transgenic plants was developed for the Oriental hybrid lily, Lilium cv. Acapulco, by Agrobacterium-mediated genetic transformation. Filament-derived calli were co-cultivated with A. tumefaciens strain EHA101/pIG121Hm, which harbored a binary vector carrying the neomycin phosphotransferase II, hygromycin phosphotransferase, and intron-containing -glucuronidase genes in the T-DNA region. Six hygromycin-resistant (Hyg^r) culture lines were obtained from 200 calli by scratching them with sandpaper prior to inoculation and using NH₄NO₃-free medium for co-cultivation and a hygromycin-containing regeneration medium for selection. Hyg^r culture lines regenerated shoots, which developed into plantlets following transfer to a plant growth regulator-free medium. All of these plantlets were verified to be transgenic by GUS histochemical assay and inverse PCR analysis.Abbreviations AS Acetosyringone (3,5-dimethoxy-4-hydroxy-acetophenone) - BA Benzyladenine - CaMV Cauliflower mosaic virus - GUS -Glucuronidase - HPT Hygromycin phosphotransferase - Hyg^r Hygromycin-resistant - NOS Nopaline synthase - NPTII Neomycin phosphotransferase II - PGR Plant growth regulator - PIC Picloram (4-amino-3,5,6-trichloropicolinic acid)Communicated by H. Ebinuma     

cDNA cloning,functional expression and antifungal activities of a dimeric plant defensin SPE10 from <Emphasis Type="Italic">Pachyrrhizus erosus</Emphasis> seeds

SPE10 is an antifungal protein isolated from the seeds of Pachyrrhizus erosus. cDNA encoding a 47 amino acid peptide was cloned by RT-PCR and the gene sequence proved SPE10 to be a new member of plant defensin family. The synthetic cDNA with codons preferred in yeast was cloned into the pPIC9 plasmid directly in-frame with the secretion signal -mating factor, and highly expressed in methylotrophic Pichia pastoris. Activity assays showed the recombinant SPE10 inhibited specifically the growth of several pathogenic fungi as native SPE10. Circular dichroism and fluorescence spectroscopy analysis indicated that the native and recombinant protein should have same folding, though there are eight cystein residues in the sequence. Several evidence suggested SPE10 should be the first dimeric plant defensin reported so far.Nucleotide sequence data reported in this paper are available in the DDBJ/EMBL/GenBank database under accession number AY679170     

Foreign exploration for Scirtothrips perseae Nakahara (Thysanoptera: Thripidae) and associated natural enemies on avocado (Persea americana Miller)

Scirtothrips perseae Nakahara was discovered attacking avocados in California, USA, in 1996. Host plant surveys in California indicated that S. perseae has a highly restricted host range with larvae being found only on avocados, while adults were collected from 11 different plant species. As part of a management program for this pest, a “classical” biological control program was initiated and foreign exploration was conducted to delineate the home range of S. perseae, to survey for associated natural enemies and inventory other species of phytophagous thrips on avocados grown in Mexico, Guatemala, Costa Rica, the Dominican Republic, Trinidad, and Brazil. Foreign exploration efforts indicate that S. perseae occurs on avocados grown at high altitudes (>1500 m) from Uruapan in Mexico south to areas around Guatemala City in Guatemala. In Costa Rica, S. perseae is replaced by an undescribed congener as the dominant phytophagous thrips on avocados grown at high altitudes (>1300 m). No species of Scirtothrips were found on avocados in the Dominican Republic, Trinidad, or Brazil. In total, 2136 phytophagous thrips were collected and identified, representing over 47 identified species from at least 19 genera. The significance of these species records is discussed. Of collected material 4% were potential thrips biological control agents. Natural enemies were dominated by six genera of predatory thrips (Aeolothrips, Aleurodothrips, Franklinothrips, Leptothrips, Scolothrips, and Karnyothrips). One genus each of parasitoid (Ceranisus) and predatory mite (Balaustium) were found. Based on the results of our sampling techniques, prospects for the importation of thrips natural enemies for use in a “classical” biological control program in California against S. perseae are not promising.     

Phylogeny of cardinalfishes (Teleostei: Gobiiformes: Apogonidae) and the evolution of visceral bioluminescence

The cardinalfishes (Apogonidae) are a diverse clade of small, mostly reef-dwelling fishes, for which a variety of morphological data have not yielded a consistent phylogeny. We use DNA sequence to hypothesize phylogenetic relationships within Apogonidae and among apogonids and other acanthomorph families, to examine patterns of evolution including the distribution of a visceral bioluminescence system. In conformance with previous studies, Apogonidae is placed in a clade with Pempheridae, Kurtidae, Leiognathidae, and Gobioidei. The apogonid genus Pseudamia is recovered outside the remainder of the family, not as sister to the superficially similar genus Gymnapogon. Species sampled from the Caribbean and Western Atlantic (Phaeoptyx, Astrapogon, and some Apogon species) form a clade, as do the larger-bodied Glossamia and Cheilodipterus. Incidence of visceral bioluminescence is found scattered throughout the phylogeny, independently for each group in which it is present. Examination of the fine structure of the visceral bioluminescence system through histology shows that light organs exhibit a range of morphologies, with some composed of complex masses of tubules (Siphamia, Pempheris, Parapriacanthus) and others lacking tubules but containing chambers formed by folds of the visceral epithelium (Acropoma, Archamia, Jaydia, and Rhabdamia). Light organs in Siphamia, Acropoma, Pempheris and Parapriacanthus are distinct from but connected to the gut; those in Archamia, Jaydia, and Rhabdamia are simply portions of the intestinal tract, and are little differentiated from the surrounding tissues. The presence or absence of symbiotic luminescent bacteria does not correlate with light organ structure; the tubular light organs of Siphamia and chambered tubes of Acropoma house bacteria, those in Pempheridae and the other Apogonidae do not.     

Effects of sex and age of a dioecious tree, <Emphasis Type="Italic">Forchhammeria pallida</Emphasis> (Capparaceae) on the performance of its primary herbivore, <Emphasis Type="Italic">Murgantia varicolor</Emphasis> (Hemiptera: Pentatomidae)

The effects of sex and age of a dioecious tree, Forchhammeria pallida, on the survival and development of a Mexican harlequin bug, Murgantia varicolor, were examined. In the laboratory, bugs reared on fruits or fruits and leaves developed rapidly and had a high rate of survivorship, whereas bugs reared on leaves alone developed slowly after the second instar and died by the fifth instar. Murgantia varicolor showed a preference for leaves from juvenile plants over leaves from mature plants, and bugs reared on leaves from juvenile plants survived significantly longer than those reared on leaves from mature plants. Murgantia varicolor showed no preference for feeding on leaves of mature male versus mature female plants. In the field, M.varicolor occurred on male, female and juvenile plants. Although nymphs were less common on male than female F.pallida, their presence in substantial numbers shows that M.varicolor oviposits on both male and female plants. However, adult M.varicolor were rare on male plants. This result is supported by the inability of nymphs to complete their development on vegetative parts of F.pallida in the laboratory. These observations suggest that dioecy in F.pallida may be disruptive to populations of M.varicolor.     

外来树种日本落叶松和日本花柏对鄂西北森林群落的影响

【目的】研究大面积栽植外来树种日本落叶松和日本花柏对鄂西北森林群落物种多样性的影响,为评价外来树种的入侵风险提供依据。【方法】采用样地调查法对比研究外来树种日本落叶松和日本花柏人工林与当地森林群落特征差异。【结果】日本落叶松人工林样地林下植物种类丰富,样地平均物种数与当地天然林样地物种数相比无显著差异;林下灌木层和草本层多样性指数较高,草本层多样性指数与当地天然林相比无显著差异;林下未发现日本落叶松的更新苗。日本花柏人工林样地平均物种数显著少于当地其他人工林样地;乔木层、灌木层和草本层的4个多样性指数值均小于当地其他人工林样地;在3个样地中出现日本花柏更新苗,更新苗数量达479株·hm~(-2)。【结论】引种栽培日本落叶松不会导致当地森林群落的物种多样性降低,不会引起生物入侵风险;但引种栽培日本花柏会明显降低当地森林群落的物种多样性,对当地森林生态系统的稳定构成一定威胁。     

Natural variation of ascospore and conidial germination by Fusarium verticillioides and other Fusarium species

Fusarium verticillioides and other Fusarium species were examined for their spore germination phenotypes. In general, germinating spores of F. verticillioides formed germ tubes that immediately penetrated into agar. Such invasive germination was the predominant growth phenotype among 22 examined field isolates of F. verticillioides from a broad range hosts and locations. However, two of the field isolates were unique in that they formed conidial germ tubes and hyphae that grew along the surface of agar before penetration eventually occurred. Conidia of 22 other Fusarium species were assessed for their germination phenotypes, and only some strains of F. annulatum, F. fujikuroi, F. globosum, F. nygamai, and F. pseudoanthophilum had the surface germination phenotype (21 % of the strains assessed). Sexual crosses and segregation analyses involving one of the F. verticillioides surface germination strains, NRRL 25059, indicated a single locus, designated SIG1 (surface vs. invasive germination), controlled the germ tube growth phenotypes exhibited by both conidia and ascospores. Perfect correlation was observed between an ascospore germination phenotype and the germination phenotype of the conidia produced from the resulting ascospore-derived colony. Recombination data suggested SIG1 was linked (7 % recombination frequency) to FPH1, a recently described locus necessary for enteroblastic conidiogenesis. Corn seedling blight assays indicated surface germinating strains of F. verticillioides were less virulent than invasively germinating strains. Assays also indicated pathogenicity segregated independently of the FPH1 locus. Invasive germination is proposed as the dominant form of spore germination among Fusarium species. Furthermore, conidia were not necessary for corn seedling disease development, but invasive germination may have enhanced the virulence of conidiating strains.     

檀香与不同豆科植物寄生关系的研究

为了解檀香(Santalum album L.)与不同豆科植物的寄生关系,选取11种具有重要经济价值的豆科植物和檀香一起种植,对檀香叶片的光合特征和株高、地径以及寄主植物根系的吸器大小进行了测定。结果表明,檀香的吸器大小、数量在不同寄主之间存在很大差异,不同寄主对檀香的株高、地径也有显著差异。檀香的优良寄主有美洲合欢(Calliandra haematocephala)、苏木(Caesalpinia sappan)、台湾相思(Acacia confusa)、龙牙花(Erythrina corallodendron);一般的寄主植物有马占相思(Acacia mangium)、降香黄檀(Dalbergia odorifera)、黄槐(Cassia surattensis);不适宜的寄主植物有凤凰木(Delonix regia)、海南红豆(Ormosia pinnata)、银合欢(Leucaena leucocephala)、洋紫荆(Bauhinia blakeana)。同时,檀香的株高、地径及光合特征和吸器数量密切相关。因此,檀香种植时应选择适宜的优良寄主植物。     

Microorganisms asssociated with Withania somnifera leaves

Microorganisms including bacteria, actinomycetes and fungi were recovered from the leaves of Withania somnifera, which were collected from two altitudinal ranges (0–300 m and 1700–2000 m) in the Asir region, Saudi Arabia. Types and numbers of microorganisms varied according to the altitude and the month of collection. The number of microorganisms was higher on old leaves than that on young ones in most cases. Low altitude exhibited more microorganisms than high altitude. The relationship between meteorological factors and type and number of the recovered microorganisms is discussed. Inoculation of detached healthy leaves of Withania by all recovered fungal species revealed only Alternaria solani as a pathogen of this plant. To confirm pathogenicity, scanning and transmission electron microscopic examination revealed the colonization of this pathogen inside the leaf tissue. Penetration of Withania leaves by the fungus occurred only through stomata, and the invading hyphae were located in the intercellular spaces of leaf tissues. Ultrastructural changes noted in infected cells included changes in chloroplasts and the invagination of the host plasma membrane.     

Screening of plant extracts for antimicrobial activity against bacteria and yeasts with dermatological relevance

There is cumulative resistance against antibiotics of many bacteria. Therefore, the development of new antiseptics and antimicrobial agents for the treatment of skin infections is of increasing interest. We have screened six plant extracts and isolated compounds for antimicrobial effects on bacteria and yeasts with dermatological relevance. The following plant extracts have been tested: Gentiana lutea, Harpagophytum procumbens, Boswellia serrata (dry extracts), Usnea barbata, Rosmarinus officinalis and Salvia officinalis (supercritical carbon dioxide [CO2] extracts). Additionally, the following characteristic plant substances were tested: usnic acid, carnosol, carnosic acid, ursolic acid, oleanolic acid, harpagoside, boswellic acid and gentiopicroside. The extracts and compounds were tested against 29 aerobic and anaerobic bacteria and yeasts in the agar dilution test. U. barbata-extract and usnic acid were the most active compounds, especially in anaerobic bacteria. Usnea CO2-extract effectively inhibited the growth of several Gram-positive bacteria like Staphylococcus aureus (including methicillin-resistant strains - MRSA), Propionibacterium acnes and Corynebacterium species. Growth of the dimorphic yeast Malassezia furfur was also inhibited by Usnea-extract. Besides the Usnea-extract, Rosmarinus-, Salvia-, Boswellia- and Harpagophytum-extracts proved to be effective against a panel of bacteria. It is concluded that due to their antimicrobial effects some of the plant extracts may be used for the topical treatment of skin disorders like acne vulgaris and seborrhoic eczema.     

Tracking down the "head blob": comparative analysis of wingless expression in the developing insect procephalon reveals progressive reduction of embryonic visual system patterning in higher insects

The evolution of larval head morphology in holometabolous insects is characterized by reduction of antennal appendages and the visual system components. Little insight has been gained into molecular developmental changes underlying this morphological diversification. Here we compare the expression of the segment polarity gene wingless (wg) in the pregnathal head of fruit fly, flour beetle and grasshopper embryos. We provide evidence that wg activity contributes to segment border formation, and, subsequently, the separation of the visual system and protocerebrum anlagen in the anterior procephalon. In directly developing insects like grasshopper, seven expression domains are formed during this process. The activation of four of these, which correspond to polar expression pairs in the optic lobe anlagen and the protocerebral ectoderm, has shifted to postembryonic stages in flour beetle and Drosophila. The remaining three domains map to the protocerebral neuroectoderm, and form by disintegration of a large precursor domain in flour beetle and grasshopper. In Drosophila, the precursor domain remains intact, constituting the previously described “head blob”. These data document major changes in the expression of an early patterning gene correlated with the dramatic evolution of embryonic visual system development in the Holometabola.     

Molecular phylogeny of Phebalium (Rutaceae: Boronieae) and related genera based on the nrDNA regions ITS 1+2

Parsimony analyses of the internal transcribed spacer regions of nuclear ribosomal DNA (ITS 1 & ITS 2) for 38 taxa sampled from the Phebalium group (Rutaceae: Boronieae) and two outgroups confirm that, with the exception of Phebalium sensu stricto and Rhadinothamnus, six of the currently recognised genera within the group are monophyletic. The data indicate that Phebaliums. str. is paraphyletic with respect to Microcybe, and Rhadinothamnus is paraphyletic with respect to Chorilaena. Rhadinothamnus and Chorilaena together are the sister group to Nematolepis. Drummondita, included as an outgroup taxon, clustered within the ingroup as sister to Muiriantha and related to Asterolasia.The phylogeny suggests that the evolution of major clades within a number of these genera (e.g. Phebalium) relates to vicariance events between eastern and south-western Australia. Leionema is an eastern genus, with the most basal taxon being the morphologically distinct Leionema ellipticum from northern Queensland. Leionema also includes one species from New Zealand, but this species (as with some others) proved difficult to sequence and its phylogenetic position remains unknown. Taxonomic changes at the generic level are recommended.The authors wish to thank Paul G.Wilson, PERTH, for advice and discussion, and Paul Forster, BRI, for collecting and providing material of Leionema ellipticum. The project was supported by a Melbourne University Postgraduate Award (to BM), the Australian Biological Resources Study (ABRS), Australian Systematic Botany Society and Wolf Den (Australia) Investments.     

广藿香叶盘法高效再生体系主要影响因素的研究

广藿香是重要的芳香药用植物,利用基因工程技术对广藿香进行品种改良,需要建立一个高效的广藿香植株再生体系。该研究以广藿香无菌苗叶片为材料,将叶盘外植体分别置于不同条件下培养,观察、统计其再生植株的数量及生长状况。通过研究15~50 d的苗龄、第2~4节上的叶及培养基中2,4-D、NAA、BA和KT的浓度和配比等因素对广藿香叶盘再生植株的影响,在此基础上优化培养条件,建立广藿香高效再生体系。结果表明:广藿香无菌苗的苗龄、叶片在茎上的着生位置以及培养基中的植物生长调节物质浓度和配比都对广藿香的植株再生有显著影响;优化培养条件为以培养30 d的广藿香无菌苗顶芽下第2对展开叶片切割的叶盘为外植体,在含0.1 mg·L-1NAA和0.5 mg·L-1BA的MS培养基中培养28 d,叶盘的不定芽发生频率达到100%,单个叶盘的平均再生芽数为96.5个,经生根培养及温室炼苗,再生植株的移栽成活率达到96%。广藿香叶盘植株再生体系的建立为其基因转化研究及优良品种的快速繁育奠定了基础。