假臭草水浸提液对4种作物的化感作用

【背景】假臭草是近几年来入侵我国南方的外来杂草,目前已成功侵占海南、福建、广东等省沿海的大部分果园、草地、农田等农业生态系统,给当地农业生产造成极大的危害。【方法】采用室内生物测定方法研究不同浓度的假臭草水浸提液(0.010、0.025、0.050 g·m L~(-1))对4种作物(西瓜、水稻、萝卜和辣椒)种子萌发和幼苗生长的化感作用。【结果】各浓度的假臭草水浸提液对4种作物种子萌发和幼苗生长都有较强的化感作用,并且随着浸提液浓度的增大,化感效应显著增强。当浓度为0.050 g·m L~(-1)时,4种受体作物的化感综合效应顺序为西瓜萝卜水稻辣椒。【结论与意义】明确假臭草对不同供试作物的化感作用,能够为该入侵杂草的科学防治提供理论依据。     

不同铅水平下紫茎泽兰细胞内铅的分布和化学形态的分析

该研究运用差速离心法和化学试剂逐步提取法,分析了重金属铅在紫茎泽兰亚细胞内的分布和主要化学形态。结果表明:随着Pb浓度的升高,紫茎泽兰的叶、根、茎中各亚细胞组分Pb含量逐渐增加;紫茎泽兰中的Pb在叶片分布于可溶性部分和细胞壁中,两者占总量的75.34%~84.63%;茎也主要分布于可溶性部分和细胞壁中,占总量的36.10%~57.14%和20.07%~36.52%;而在根中则富集于细胞壁和可溶性部分,分别占39.2%~49.78%和28.27%~37.62%,其他细胞器中的Pb含量均较少。紫茎泽兰叶中的Pb以盐酸提取态和水提取态为主,两者占总量的58.74%~73.04%;茎中的Pb以醋酸提取态和氯化钠提取态为主;而根中的Pb则以醋酸提取态和盐酸提取态占优势,两者占总量的39.15%~52.91%。     

Effects of virus infection and growth irradiance on fitness components and photosynthetic properties of Eupatorium makinoi (Compositae)

We examined the effects of geminivirus infection on fitness components and on photosynthetic properties of the host plant, Eupatorium makinoi, grown at two irradiance levels in a natural-light greenhouse. Under the low-light condition (13% full sunlight), more than a half of the infected plants died during the 9-mo experiment, while most of uninfected plants survived. Growth rate was also lowered by infection. At high light (50% full sunlight), by contrast, virus infection did not cause mortality despite slight decrease in growth rate. Flowering occurred only at high light, and reproductive outputs of the plants were markedly reduced by the infection. Infected leaves had distinct yellow variegations and, when compared with uninfected leaves, they showed (1) comparable light-saturated photosynthetic rate per unit area, but (2) lower initial slope of light-response curve of photosynthesis on an incident irradiance basis. The lower initial slope was mainly due to reduction of light-harvesting chlorophyll-protein complexes in the variegated parts. Since the differences in plant performance, depending both on infection and on growth irradiance, were largely explained by the differences in growth rate and/or plant size, the reduced photosynthetic production in the infected plants would be a major factor explaining the inferior performance of the host plants.     

紫茎泽兰微生物发酵生产木糖醇的工艺

木糖醇（ｘｙｌｉｔｏｌ）是一种天然五碳多元醇,存在于许多水果、蔬菜及蘑菇中,但含量均很低,其中以蘑菇（ＡｇａｒｉｃｕｓｃａｍｐｅｓｔｒｉｓＬ．ｅｘＦｒ．）含量较高,约为１００ｍｇ／ｋｇ（干重）;木糖醇也是一种常见的代谢中间体,存在于哺乳动物的碳水化合...     

Genetic variation of geminiviruses: comparison between sexual and asexual host plant populations

One of the most promising hypotheses for the evolution of sex is that sexual reproduction is advantageous because it increases the rate of adaptive evolution in response to parasites. To investigate this advantage of sex, we compared genetic variation of geminiviruses infecting sexual and asexual populations of Eupatorium (Asteraceae). The infection frequency was 37.5% in the sexual population and 87.8% in the asexual population. The lower infection frequency in the sexual population might be the result of higher genetic diversity of host plants. If geminiviruses have diverged to counter defence systems of genetically variable hosts, genetic diversity of viruses is expected to be higher in sexual host populations than in asexual host populations. To test this expectation, we used single-strand conformation polymorphism (SSCP) analysis to examine genetic diversity of the geminiviruses in a DNA region containing the open-reading frame (ORF) C4 gene, which is known to function as a host range determinant. As predicted, higher genetic diversity of viruses was observed in the sexual population: three SSCP types were found in the asexual population while six types were found in the sexual population. Sequencing of the polymerase chain reaction (PCR) products revealed further genetic diversity. Phylogenetic analysis of the sequences showed that the SSCP types belonged to four different clades. Several SSCP types from the same clade were found in the sexual population, whereas the asexual population included only one SSCP type from each clade. Amino acid replacements of ORF C4 are suggested to be accelerated in the sexual population. This evidence supports the hypothesis that sexual reproduction is advantageous as a defence against epidemic disease.     

Application of multidimensional gas chromatography to the enantioselective characterisation of the essential oil of Eupatorium buniifolium Hooker et Arnott

The qualitative and quantitative composition of the essential oil from aerial parts of Eupatorium buniifolium Hooker et Arnott (Asteraceae) has been investigated for the first time. The essential oils were obtained by steam distillation of leaves and analysed by GC-MS; 44 components were identified. Monoterpene and sesquiterpene hydrocarbons, especially alpha-pinene (14.7%), beta-elemene (12.2%), germacrene D (11.5%), trans-beta-guaiene (6.5%) and (E)-caryophyllene (4.3%), were the major constituents found in the oils. The characterisation of E. buniifolium by enantioselective GC was performed by evaluation of the enantiomeric ratios of alpha-pinene, sabinene, beta-pinene, limonene, terpinen-4-ol and germacrene D.     

紫茎泽兰中的酚类化学成分

从紫茎泽兰(Eupatorium adenophorum Spreng.)乙醇提取物中分离得到11个酚类化合物。通过波谱分析,分别鉴定为咖啡酸(1)、阿魏酸(2)、芥子醛(3)、苯乙基阿魏酯(4)、3,4-二羟基苯甲酸(5)、4-羟基-3-甲氧基苯甲酸(6)、3,4-二甲氧基苯甲酸(7)、没食子酸(8)、3-(3,4-二羟基苯基)-1-丙醇(9)、2-香豆酸-β-D-吡喃葡萄糖苷(10)和4-O-β-D-葡萄糖苷-3,5-二甲氧基苯基-乙基酮(11)。化合物3~9和11为首次从紫茎泽兰中分离得到。     

泽兰实蝇内生殖器官的结构及其发育状况

【背景】泽兰实蝇属双翅目实蝇科,是杂草紫茎泽兰的重要专性天敌。该蝇幼虫可蛀入紫茎泽兰内部形成虫瘿,有效控制紫茎泽兰的扩散,许多国家都利用泽兰实蝇控制紫茎泽兰的危害。【方法】通过光学显微法观察了泽兰实蝇成虫内生殖器官的结构及其发育动态。【结果】雌性泽兰实蝇的内生殖系统主要由卵巢、输卵管、受精囊、雌性附腺等器官组成,雄性生殖系统由精巢、输精管、雄性附腺、射精管组成。在成虫发育过程中,雌虫卵巢的长度在第4日龄时达最大值,宽度在1日龄时达最大值,与其他日龄相比有显著差异,雌性附腺及受精囊的大小在各日龄间无显著差异;雄虫精巢长度在4日龄时达到最大,宽度在2日龄时达最大,且不同日龄间也有显著差异,而雄性附腺的大小在不同龄期间无显著差异。【结论与意义】本文阐明了泽兰实蝇的内生殖系统结构与发育状况,这有助于为提高泽兰实蝇人工繁殖效率及生物防治效果奠定理论基础。     

棉蚜和七星瓢虫对紫茎泽兰挥发物的行为反应及挥发物化学成分初步分析

田间调查 发现紫茎泽兰Eupatorium adenophorum Spreng上有一定数量的棉蚜Aphis gossypii寄生。从棉蚜是否可为紫茎泽兰的生物防治提供新思路的角度出发,研究了紫茎泽兰挥发性气味物质的化学组成及其对棉蚜和七星瓢虫Coccinella septempunctata行为的影响。棉蚜选择性试验结果表明：紫茎泽兰饲养的棉蚜对紫茎泽兰的趋向率为62.5%,对棉花的趋向率为37.5%。棉花饲养的棉蚜对紫茎泽兰的趋向率为30%,对棉花的趋向率为70%。在七星瓢虫对感染蚜虫植株的选择性实验中,七星瓢虫对感染蚜虫的紫茎泽兰植株气味趋向率为29.2%,对感染蚜虫的棉花植株气味趋向率为70.8%;七星瓢虫对除去植株的两种蚜虫气味选择率没有显著差异,对取食紫茎泽兰的蚜虫气味选择率为46.7%,对取食棉花植株的蚜虫气味选择率为53.3%。通过GC-MC分析了紫茎泽兰挥发性化学物质的组分及相对含量,其主要挥发物的成分是α-蒎烯、莰烯、β-蒎烯、2-蒈烯和α-水芹烯等。     

紫茎泽兰Eupatorium adenophorum Spreng.在中国入侵分布预测

原产于墨西哥的紫茎泽兰Eupatorium adenophorum Spreng.作为一个有害的外来物种在印度、新西兰和澳大利亚生长已有很长时间。在中国,尤其是在南方和西南地区其蔓延速度之快,带来了不可忽视的经济和社会后果。我们采用了生态位模拟新方法来预测紫茎泽兰可能入侵的范围。据此,预测的潜在分布区包括该植物在中国境内已分布的省份及未来华中、华东易受入侵的区域。