Susceptibility of plants to attack by wireworms (Agriotes spp.)

In laboratory tests, larvae of Agriotes spp. were presented with a choice between seedlings of test plants, and of wheat, which is known to be susceptible. Some plants, e.g. onion, were as susceptible as wheat to wireworm attack whilst others (mustard, cabbage, French marigold, clover and flax) were less often attacked, partly because they are small and are shallow sown. All pea and bean plants exposed to wireworms were attacked but most tolerated attack and continued to grow.     

Vulnerability of riparian zones to invasion by exotic vascular plants

We compared the invasibility of riparian plant communities high on river banks with those on floodplain floors for four South African rivers. Analyses of abundant and significant riparian species showed that the floors have 3.1 times more exotic plants than the banks. The percent exotics ranges from 5% to 11% of total species richness for the banks, and from 20% to 30% for the floors. Species richness and percent exotics are negatively correlated for the banks, but not correlated for the floors.Despite great differences in climate, species richness, and landuse history, the percentages of exotic plants in three rivers in the Pacific Northwest of the USA and one river in southwestern France are similar to those in South Africa (24-30% vs. 20-30%, respectively). Furthermore, the high proportions of exotic species in these riparian plant communities are comparable to those reported for vascular plant communities on islands. We conclude that the macro-channel floor regions of the riparian zones of South African rivers are highly vulnerable to invasion by exotic vascular plants.     

Susceptibility of previously damaged strawberry plants to mite attack

Using radioactive labelling techniques on two cultivars of strawberry (Fragaria grandiflora Duch.) and on the two-spotted spider mite (Tetranychus urticae Koch) which fed on them, differential feeding was monitored. Leaves of the susceptible cultivar Georg Soltwedel previously damaged by mites were more attractive for spider mites than leaves of undamaged plants. The opposite was observed when the resistant cultivar Macherauch's Frühernte was investigated. The results are discussed according to the induced resistance hypothesis.     

Rice plants response to the disruption of OsCSLD4 gene

The plant cell wall is a complex polysaccharide network and performs important developmental and physiological functions far beyond supplying the physical constrains. Plant cells have the ability to react to cell wall defects as exhibited by changes in gene expression, accumulation of ectopic lignin, stress responses and growth arrest. It is a major challenge to understand how plants sense and respond to wall integrity since very little is known about the signaling involved in the responses. Cellulose synthase-like D (CSLD) proteins mediating the biosynthesis of a wall polysaccharide polymer make up a common subfamily to all plants. Recently, we have reported the functional characterization of CSLD4 in rice. Mutations in OsCSLD4 show morphological alterations and pleiotropic effects on wall compositions and structure. Our study demonstrates that OsCSLD4 play a critical role in cell wall formation and plant growth. Here we show the subtle wall alterations by separating the culm residues into five fractions. Quantitative RT-PCR analysis further revealed that the expression of various genes involved in xylan synthesis and cell cycle regulation was altered in mutant plants, as the responses to OsCSLD4 disruption. Therefore, plants may have fine sensory machinery to react to wall defects and modulate growth for adapting to the changes.Key words: OsCSLD4, cell wall biosynthesis, plant development, wall integrity, rice     

Susceptibility to murine cholesterol gallstone formation is not affected by partial disruption of the HDL receptor SR-BI

High density lipoprotein (HDL) promotes reverse cholesterol transport from peripheral tissues to the liver where its cholesterol is secreted preferentially into bile. The scavenger receptor class B type I (SR-BI) is believed to play a pivotal role in unloading HDL cholesterol and its ester to hepatocytes. Here, using male SR-BI "att" mice with a dysfunctional mutation in the Sr-b1 promoter, we studied whether approximately 50% of normal SR-BI expression influences gallstone susceptibility in these mice fed a lithogenic diet containing 1% cholesterol, 0.5% cholic acid and 15% butterfat. Our results showed that the disruption of SR-BI expression reduced cholesterol secretion by 37% in the chow-fed state and 10% on the lithogenic diet, and while delaying incidence slightly, did not influence cumulative susceptibility to cholesterol gallstones. The lithogenic diet induced marked increases in biliary cholesterol and phospholipid secretion rates but not of bile salts. Basal expression of hepatic SR-BI protein was dissimilar in both wild-type and SR-BI mice, and remained unaltered in response to the lithogenic diet. By two independent dual isotope methods, intestinal cholesterol absorption was unimpaired by attenuation of the SR-BI which also displays low-density expression on small intestinal enterocytes. We conclude that although HDL cholesterol is a principal source of biliary cholesterol in the basal state, uptake of cholesterol from chylomicron remnants appears to be the major contributor to biliary cholesterol hypersecretion during diet-induced cholelithogenesis in the mouse.     

水生维管植物研究:II、水生维管植物对干涸的适应

根据实地考察和文献分析 ,研究了水生维管植物对干涸的不同的适应对策 ,归纳为 3类 :(1 )直接适应型 (或称生理适应型 ) ;(2 )间接适应型 ;(3 )休眠适应型。这有助于认识水生植物的适应特征 ,揭示干涸对部分水生植被演替的作用。     

A tritrophic signal that attracts parasitoids to host-damaged plants withstands disruption by non-host herbivores

Background  

Volatiles emitted by herbivore-infested plants are highly attractive to parasitoids and therefore have been proposed to be part of an indirect plant defense strategy. However, this proposed function of the plant-provided signals remains controversial, and it is unclear how specific and reliable the signals are under natural conditions with simultaneous feeding by multiple herbivores. Phloem feeders in particular are assumed to interfere with plant defense responses. Therefore, we investigated how attack by the piercing-sucking cicadellid Euscelidius variegatus influences signaling by maize plants in response to the chewing herbivore Spodoptera littoralis.     

Susceptibility to powdery mildew of wheat plants deficient in copper

Summary Wheat plants were grown in deep pots at three levels of copper nutrition in an open-sided glasshouse where they were subject to natural infection by powdery mildew. Plant growth and the degree of infection of each leaf were assessed weekly throughout the life of the plants.During the middle phase of growth especially — from tillering to anthesis — severity of infection of leaves was decreased by increasing the level of copper supply. Stems of copper-deficient plants were also severely infected. In these plants serious disease was sustained until final harvest. The results are discussed in relation to known and speculative roles of copper in plants.     

Herbivore-driven disruption of arbuscular mycorrhizal carbon-for-nutrient exchange is ameliorated by neighboring plants

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Plasmodesmata: intercellular tunnels facilitating transport of macromolecules in plants

The major structural and enzymatically active protein in spicules from siliceous sponges, e.g., for Suberites domuncula studied here, is silicatein. Silicatein has been established to be the key enzyme that catalyzes the formation of biosilica, a polymer that represents the inorganic scaffold for the spicule. In the present study, it is shown, by application of high-resolution transmission and scanning transmission electron microscopy that, during the initial phase of spicule synthesis, nanofibrils with a diameter of around 10 nm are formed that comprise bundles of between 10 and 20 nanofibrils. In intracellular vacuoles, silicasomes, the nanofibrils form polar structures with a pointed tip and a blunt end. In a time-dependent manner, these nanofibrillar bundles become embedded into a Si-rich matrix, indicative for the formation of biosilica via silicatein molecules that form the nanofibrils. These biosilicified nanofibrillar bundles become extruded from the intracellular space, where they are located in the silicasomes, to the extracellular environment by an evagination process, during which a cellular protrusion forms the axial canal in the growing spicule. The nanofibrillar bundles condense and progressively form the axial filament that becomes localized in the extracellular space. It is concluded that the silicatein-composing nanofibrils act not only as enzymatic silica bio-condensing platforms but also as a structure-giving guidance for the growing spicule.     

Antimicrobial activity of vascular plants

Numerous surveys have demonstrated the wide occurrence of active antimicrobial substances in higher plants. The array of compounds with unique structures which plants produce has served as a stimulus to continued search for useful antibiotics. Reports referred to in the table indicate that active substances have been found in plants from 157 families.     

The relationships of vascular plants

Recent phylogenetic research indicates that vascular plants evolved from bryophyte-like ancestors and that this involved extensive modifications to the life cycle. These conclusions are supported by a range of systematic data, including gene sequences, as well as evidence from comparative morphology and the fossil record. Within vascular plants, there is compelling evidence for two major clades, which have been termed lycophytes (clubmosses) and euphyllophytes (seed plants, ferns, horsetails). The implications of recent phylogenetic work are discussed with reference to life cycle evolution and the interpretation of stratigraphic inconsistencies in the early fossil record of land plants. Life cycles are shown to have passed through an isomorphic phase in the early stages of vascular plant evolution. Thus, the gametophyte generation of all living vascular plants is the product of massive morphological reduction. Phylogenetic research corroborates earlier suggestions of a major representational bias in the early fossil record. Mega-fossils document a sequence of appearance of groups that is at odds with that predicted by cladogram topology. It is argued here that the pattern of appearance and diversification of plant megafossils owes more to changing geological conditions than to rapid biological diversification.     

Ecophysiology of Antarctic vascular plants

Most of the ice and snow-free land in the Antarctic summer is found along the Antarctic Peninsula and adjacent islands and coastal areas of the continent. This is the area where most of the Antarctic vegetation is found. Mean air temperature tends to be above zero during the summer in parts of the Maritime Antarctic. The most commonly found photosynthetic organisms in the Maritime Antarctic and continental edge are lichens (around 380 species) and bryophytes (130 species). Only two vascular plants, Deschampsia antarctica Desv. and Colobanthus quitensis (Kunth) Bartl., have been able to colonize some of the coastal areas. This low species diversity, compared with the Arctic, may be due to permanent low temperature and isolation from continental sources of propagules. The existence of these plants in such a permanent harsh environment makes them of particular interest for the study of adaptations to cold environments and mechanisms of cold resistance in plants. Among these adaptations are high freezing resistance, high resistance to light stress and high photosynthetic capacity at low temperature. In this paper, the ecophysiology of the two vascular plants is reviewed, including habitat characteristics, photosynthetic properties, cold resistance, and biochemical adaptations to cold.     

Cell response to penetration by informational macromolecules]

A relation is shown between the kinetic for of DNA uptake by the thymocytes (extremal or monotonous), the level of uptake (low or high) and the origin of DNA (hetero-or homologous). Preliminary irradiation of cells promotes a manifestation of a cytopathogenous effect of the heterologous DNA. The association between the cytopathogenous effect of DNA and that of its information characteristics has been confirmed. The demonstration of cytopathogenous effects of native and degraded DNA was studied as a function of time of their storage. The chromatographic analysis of dispersion of the molecular weights of preparations at different time of their starage allowed a conclusion of the important role played by structure defects in manifestation of cytopathogenous properties of DNA.     

Susceptibility of zinc-deficient wheat plants to colonization byFusarium graminearum Schw. Group 1

Wheat plants were grown at three levels of zinc nutrition in potted soil under controlled conditions. The surface soil in half of the pots was inoculated with a thin layer of milled chaff colonized byFusarium graminearum Group 1. Forty days after sowing, the plants were assessed for dry matter production and the extent of colonization by the pathogen. The concentration of zinc in the plant tissues was also determined.The zinc status of the plants ranged from severe deficiency through subclinical deficiency to sufficiency. The extent of colonization above the point of infection was decreased significantly by increasing the level of zinc supply. However, colonization of the seminal or secondary roots was not affected by zinc supply, nor was the incidence of infected plants. The unidirectional effect on resistance suggests that zinc has modified the contribution of the xylem flux to the upward spread of the pathogen.     

上海维管植物研究综述

该文总结《上海植物志》出版以来的维管植物区系资料,分析整理存疑种、订正了错误鉴定,并发表上海植物新记录4种.据此确认上海目前有原生维管植物126科440属818种(包括7亚种、49变种、2变型),外来逸生植物86科234属367种(包括2亚种、18变种).结果表明上海植物区系受人为干扰较严重.     

Signal transduction in vascular plants

We review current evidence for the presence and activity in plants of several paradigmatic components of transmembrane signal transduction systems. Components considered include the second messengers calcium, inositol 1,4,5-trisphosphate, and cyclic AMP; protein kinases and protein phosphatases; and G-proteins. At the current stage of development of the field of plant signal transduction, broad similarities between plant and the more well-studied animal systems are apparent. However, there also exist considerable differences in detail.