四种植物粘液繁殖体粘液的比较研究

对百里香(Thymus serpyllum)、平车前(Plantago depressa)、盐生车前(P．maritima)、野亚麻(Linum stelleroides)进行了粘液繁殖体粘液情况比较．以在水浸和浇水条件下植物种子粘沙量的多少衡量粘液量．结果表明,对于不同浸水时间处理,野亚麻和平车前未表现明显差异,盐生车前和百里香有随浸泡时间加长而粘液溶出量增多的趋势．对于不同浇水量处理,4种植物均有随浇水量增多而粘液增多的倾向．浸泡80min后,盐生车前种子的粘液粘沙使重量达原重的60多倍,平车前种子达原重的10倍左右,百里香和野亚麻种子达原重的4～6倍左右．浇水8mm后,盐生车前种子的粘液粘沙使重量达原重的20多倍,平车前种子达原重的6～10倍左右,百里香和野亚麻种子达原重的2～7倍左右．将各种处理平均,得到各种植物粘沙种子百分率为：野亚麻67．7％,百里香94．5％,平车前97．7％,盐生车前99．5％．     

白沙蒿粘液瘦果萌发中聚糖内切水解酶的活动特性

对白沙蒿( Artemisia sphaerocephaha Krasch.)种子萌发不同阶段的种胚提取物中几种可能降解果皮外层粘液物质的多糖内切酶进行了检测.研究结果表明:多聚半乳糖醛酸酶在干燥胚中已存在并具较高的活性,但其活性随着种子吸涨及萌发而降低.此酶并不释放到种胚外.β-甘露聚糖内切酶随着种子的吸涨而增加并被萌发的种胚释放到种子外.纤维素酶在种子萌发的过程中不表现出活性.提取物中的所有多糖内切酶都无法降解果皮外层的粘液物质.     

向日葵对向日葵螟抗虫性的研究进展

向日葵螟是取食向日葵花盘及籽粒最为猖獗的一种害虫,可造成严重的产量损失。本文综述了向日葵对两种向日葵螟(欧洲葵螟Homoeosoma nebulellum Denis et Schiffermüller和美洲葵螟Homoeosoma electellum Hulst)抗虫性的研究进展,从向日葵的花药腺毛、瘦果性状、次生化合物(黑色素、倍半萜类化合物和花粉萃取物)等方面概括了向日葵和向日葵螟的互作关系,阐述了向日葵的形态结构及化学组成对向日葵螟抗虫性的作用,初步说明了向日葵对向日葵螟抗虫性的物理生化机制,并对未来在抗虫育种工作的启示及可能的应用进行了展望。     

光照和温度对入侵植物大狼耙草异型瘦果萌发的影响

为了解大狼耙草(Bidens frondosa)的入侵机理,对其中央瘦果和外围瘦果的形态特征和萌发特性进行了研究。结果表明,大狼耙草果序中的中央瘦果和外围瘦果在颜色、长度、宽度和芒刺长度等方面均存在明显差异。在周期性光照下, 两种瘦果在15℃/10℃下不萌发;在20℃/15℃和25℃/20℃下中央瘦果的萌发率显著高于外围瘦果;而在30℃/25℃、35℃/30℃和40℃/35℃下两种瘦果的萌发率无显著差异。在全黑暗条件下, 中央瘦果在低于35℃/30℃时萌发受到抑制,外围瘦果在低于40℃时萌发受到抑制。光照和瘦果类型除对大狼耙草的萌发率有显著影响外,对萌发指数和萌发速率也有明显影响。大狼耙草通过异形瘦果间的萌发差异减少同胞后代间的相互竞争,增强其对不同环境的适应性,使后代获得更多的生存机会,有利于瘦果在适宜的环境条件下萌发及入侵种群的存留与扩张。     

Fruit morphology in Tragopogon L. (Compositae: Lactuceae) from the Iberian Peninsula

Achenes of all the Tragopogon species from the Iberian Peninsula were examined by means of scanning-electron microscopy and stereomicroscopy. The achenes of the eight species are described, illustrated and compared. The results are contrasted with the systematics of this genus. The isolated position of T. lamottei with regard to the other seven species is noted. A key is provided to enable the different species to be distinguished.     

Ultrastructural studies of heterocyst induction by neo-peptone in Anabaena cylindrica

Abstract An ultrastructural study has been performed to elucidate the effect of active polypeptide(s) from neo-peptone on heterocyst induction in Anabaena cylindrica [1]. There was an immediate aggregation of A. cylindrica cells and a clumping of filamentous appendages in the mucilaginous sheath on the addition of active polypeptide(s) from neo-peptone. However, there was no change in the cell wall and cell membrane ultrastructure. An increase in cell length, contortion and disintegration of thylakoids, disappearance of polyphosphate bodies and an accumulation of polyglucose bodies were observed after 18 h of treatment. The double heterocysts induced show a normal heterocyst ultrastructure with well-developed polar nodules between the heterocysts and the vegetative cells, as well as between two heterocysts.
It appears that the inductive effect of active polypeptide(s) from neo-peptone is mediated through their specific binding to filamentous appendages in the mucilaginous sheath.     

Achene Wall Anatomy and Surface Sculpturing of Lactuca L. and Related Genera （Compositae： Lactuceae） with Notes on Their Systematic Significance

The achene wail anatomy and surface sculpturing of 14 species representing Lactuca L. and related genera were Investigated to evaluate inter-and Intrageneric relationships. The achene wall anatomy of the studied species can be divided Into two types： winged and ribbed. The winged type is present in Lactuca L., Pterocypsela Shlh, Clcerblta Wallr., Chaetoserls Shlh and Stenoseris Shlh, and is characterized by protruding wings and costae in transverse section. Winged type achene mesocarps are composed of parenchymatous cells and fiber ceils, and the distinct fibrous strands are confined to the costae or wings of the achenes. The ribbed type is present in Notoseris Shih and Paraprenanthes Chang ex Shih, and Is characterized by only having costae In transverse section. Fiber cells are continuous in the costae and intercostae, in surface sculpturing, the ornamentation and the shape of epidermal cells are different among these genera. The results Indicate that L. altalca and L. serrlola should be conspeclfic, and that L. dollchophylla is probably an Intermediate taxon between Lactuca and Chaetoserls. The results also support the separation of Pterocypseia, Paraprenanthes, Notoseris, Chaetoseris and Stenoserls from Lactuca and Clcerblta as independent entitles. Close affinities between Pterocypsela and Lactuca, Paraprenanthes and Notoserls, and Chaetoserls and Stenoserls are also proposed.     

Variation in Dispersal Traits in a Narrow-endemic Plant Species, <Emphasis Type="Italic">Centaurea corymbosa</Emphasis> Pourret. (Asteraceae)

The existence of genetic variability for dispersal is a crucial issue for organisms facing increased habitat fragmentation and climate change. We study the genetic basis and evolutionary potential for diaspore traits related to dispersal in Centaurea corymbosa. Using diaspores collected in natural conditions in four of the six extant populations of this narrow-endemic plant species and diaspores produced in a common garden experiment, we study the variation for pappus and achene sizes, and diaspore mass. Using a sample of achenes from the common garden experiment, we find that the best predictor of terminal velocity is a linear combination of pappus length, achene width, and achene weight. We find significant differences among populations for all traits in both conditions, as well as significant differences among families within population. Although the differences among populations for some traits are not exactly the same in controlled conditions compared to natural conditions, the ranking of populations according to their mean trait values is consistent in both conditions. Our study is therefore one of the first to show a correlation between phenotypic differentiation for dispersal traits in natural conditions vs. controlled conditions. We also show evidence of genetic variation for traits commonly thought to be involved in dispersal ability, suggesting the potential for evolutionary changes following environmental change and management actions.Co-ordinating editor: J.F. Stuefer     

Gene Families Encoding 11S Globulin and 2S Albumin Isoforms of Jelly Fig (Ficus awkeotsang) Achenes

Seed storage proteins of plants commonly comprise several groups of multiple isoforms encoded by gene families. From about 300 expressed sequence tag (EST) clones in maturing jelly fig (Ficus awkeotsang Makino) achenes, gene families encoding precursor polypeptides of two storage protein classes, including six 11S globulin isoforms and two 2S albumin isoforms, were identified. Complete sequences encoding the precursor polypeptides of these eight storage proteins were obtained by sequencing the pertinent EST clones that contained full-length cDNA fragments. Matrix-assisted laser desorption/ionization mass spectrometry analysis confirmed the presence of these storage protein isoforms in the extract of jelly fig achenes resolved in SDS–PAGE. The amino acid compositions of the deduced storage proteins indicated that achene proteins in jelly fig are nutritive, for both isoforms of 2S albumin are sulfur-rich, and one of them is also rich in tryptophan.