Beeinflussung der Blattzellen vonFontinalis antipyretica durch den Bewuchs vonCocconeis placentula

In a special habitat near Lunz (Mittersee) long time epiphytism ofCocconeis placentula var.tenuistriata and var.klinoraphis onFontinalis antipyretica leaves causes characteristic, strongly localized alterations in the walls of affected cells. They turn brown, may thicken, and may produce cystolithe-like protuberances into the cell lumina. These reactions obviously are brought about by a specific property ofCocconeis, for other epiphytes do not cause any change. The comparison of theCocconeis vegetation on younger and olderFontinalis leaves shows a considerable variability of the reactions mentioned, and in another habitat none could be found. Apparently several factors cause these reactions. Altogether,Cocconeis placentula is not a completely harmless epiphyte under certain circumstances. The alterations of the moss cells may be interpreted partly as a premature aging process, partly as a defensive action corresponding to alterations induced by some parasitic fungi. Furthermore, the reactions ofCocconeis onFontinalis are remarkably parallel to the influence of the dinococcalean algaRaciborskia inermis onSpirogyra grevilleana.

     

Variation in the spectrum of Fusarium species on winter wheat

In 1998–2000 a monitoring of the spectrum of Fusarium species on winter wheat was carried out in the Rhineland. The epidemic spread ofFusarium spp. on wheat plants during growing season was investigated as well as the grain contamination after harvest.F avenaceum was the Fusarium species isolated most frequently followed byF culmorum, F poae andF graminearum. Microdochium nivale occurred considerably only in 1998. Both, susceptibility and plant height of the cultivars were correlated to the incidence of Fusarium species /M nivale on harvested kernels; interactions with cropping intensities were detected. The incidence ofF poae seemed to be independent of the cultivar-specific Fusarium susceptibility. Despite the lack of disease symptoms, between growth stages 45–85 mycelium ofFusarium spp. was detectable in the leaves as well as conidia on the leaf surfaces.     

The comparative effects of ethylene and l-amino-cyclopropanel- carboxylic acid on two species of Fontinalis

Abstract

Fontinalis squamosa and Fontinalis antipyretica explants were cultured with 0, 10^?4, and 10^?3 M ACC, an ethylene precursor. Synlptoms of ethylene effects included truncated apices, loss of growth capability in the apical bud, colour changes, leaf undulations, inhibition of rhizoid production, and crumpled branches and leaves. The two species responded differently to treatment, and a mode of control of morphological expression relating to currently used taxonomic characters is implicated.     

Gene mapping related to yellow green leaf in a mutant line in rice (Oryza sativa L.)

A mutant, which derived from the restorer line Jinhui10 treated with EMS, showed completely yellow green leaves, and it had low chlorophyll content and poor agronomic characteristics during the growing stage. The F1 plants from the cross between normal × the mutant showed normal green leaves, and the segregation ratio of normal to yellow green leaves was 3 : 1 in F₂ population. It indicated that the trait was controlled by a single recessive nuclear gene, temporarily designated asygl3. The geneygl3 was mapped between RM468 and RM3684 with genetic distances 8.4 cM and 1.8 cM on chromosome 3. This result would be used as genetic information for fine mapping and map-based cloning ofygl3 gene.     

Development of water stress in kale leaves of different insertion levels

The mutual relationship between the water potential (γ _w ), its components, namely the osmotic potential (γ _s ) and the pressure potential (γ _p ), and the water saturation deficit (ΔW _sat ) were determined in the leaves of different insertion levels. During the water stress development in kale plants induced by decreasing soil moisture theγ _w decreased, parallely in all the leaves but the same decrease ofγ _q was accompanied by the highest decrease of theγ _p , probably due to the accumulation of osmotically active solutes, and the lowest decrease ofγ _p in the upper leaves and with the lowest decrease ofγ _s and the highest decrease ofγ _p in the lower leaves. Also the corresponding values of the ΔW _sat were always lower in the upper than in the middle and lower leaves. Thus the upper leaves wilted at more negative values ofγ _w than the other leaves. On the contrary, during the wilting of the cut off leaves the relationship betweenγ _w and ΔW _sat in the upper, middle and lower leaves was practically the same. The very slightly higher decrease ofγ _s in the upper leaves in comparison with the other leaves was compensated by a lower deerease of theirγ _p . These changes in the ratios ofγ _w ,γ _s ,γ _p and ΔW _sat with the leaf insertion levels enabled the preference of the upper leaves in retaining the necessary water supply during the wilting of plantsin situ.     

Asexual reproduction and protonemal development in vitro in Fontinalis antipyretica Hedw.

As sporophytes are very rare and asexual propagules unknown it is generally assumed that the moss Fontinalis antipyretica spreads almost exclusively via detached shoots carried in water currents. This study of regeneration in vitro reveals that F. antipyretica produces a variety of filament systems originating from virtually every part of the gametophyte, including: cortical cells in the bases of detached shoots, the margins and abaxial surfaces of leaves, stems following leaf removal and the laminae of detached leaves. The filaments vary from protonemata comprising short rectangular cells with transverse cross-walls to unbranched rhizoids. Filamentous gemmae, liberated by schizolysis, and spherical brood cells are produced in ageing and desiccating cultures. In nature these asexual propagules are probably produced in response to falling water levels and may have an important and hitherto unsuspected role in the spread and spatial genetic structure of F. antipyretica. In F. antipyretica the high level of phenotypic plasticity, that characterizes the mature gametophytes of aquatic bryophytes, also extends to the filamentous phase in the life cycle. Major differences between axenic and contaminated cultures are likely due to positive associations between the moss and bacterial and/or fungal contaminants.     

Four new species of Smilax (Smilacaceae) from southeastern Asia

Described as new areSmilax biumbellata of the affinity ofS. nervomarginata,S. siamensis of the affinity of 5.perfoliata, and two others inSmilax sect.Macranthae:S. inversa andS. pachysandroides.Smilax inversa (characterized by strongly deflexed leaves and inflorescences on zigzag stems) andS. pachysandroides (with subsessile leaves on low simple stems) show no close resemblance to any previously known species of the section.     

Revision ofFagonia species (Zygophyllaceae) with tri- to unifoliolate and simple leaves

Summary A taxonomical revision of3 Fagonia groups, viz. the complexes ofF. arabica, F. bruguieri andF. indica, including the interrelationships between their species, is presented. These complexes are characterized by their compound tri- or reduced unifoliolate leaves. Among the truly simple-leaved species, viz.F. socotrana, F. harpago andF. ovalifolia, the confusion betweenF. socotrana and some other taxa described is considered. The different patterns of the leaf trace of simple and compound tri- to unifoliolate leaves may prove to be of systematic value.     

Virus-induced virus inhibitors from systemically virus-infected plants

After infection ofNicotiana tabacum cv. Samsun with tobacco mosaic virus (TMV) crude extracts from dark-green spots of upper leaves had a more strongly marked inhibitory effect upon TMV addedin vitro than crude extracts from the surrounding light-green tissue. Likewise, crude extracts from leaves ofNicotiana tabacum cv. Samsun showing recovery after infection with tobacco ringspot virus (TRV) were seen to have a marked inhibitory effect on TMV addedin vitro. The results obtained suggest that virus inhibitors are produced after virus infections not only in hypersensitive hosts but also in systemic hosts. Necrotizing processes are not an indispensable prerequisite of the production of virus-induced virus inhibitors.     

Water potential,water saturation deficit and their relationship in leaves of different insertion levels

The water potential (Ψ _w ) and the water saturation deficit (δW _sat) in leaves of different insertion levels of potted kale plants were simultaneously measured. In non-wilting plantsδW _sat gradually decreased andΨ _w slightly increased from the upper to the lower leaves. During the wilting of the plants induced by decreasing of soil moistureΨw practically decreased paralelly in all the leaves but the same decrease ofΨ _w was connected with the lowest increase ofδW _sat in upper leaves and the highest increase ofδW _sat in lower leaves. Not only the values ofΨ _w andδW _sat but also their relationship varied considerably with the leaf insertion levels.     

Variability amongThymelaea hirsuta (L.)Endl. populations in Egypt

The present study depicts the presence of a gradient in the morphological characters ofThymelaea hirsuta (L.)Endl. leaves which correlated with the environmental gradient prevailing in the Western Mediterranean region of Egypt. The less arid and more calcareous habitats harbour individuals with obtuse and gentle curved leaf apices and gentle involute leaf margins. With the increase of aridity and decrease of CaCO₃, the leaf apices become acute and strongly curved, and the leaf margins become strongly involuted. Significant variations in seed weight, seedling emergence and viability of seed embryos inT. hirsuta, in relation to habitat types, are also shown and discussed.     

Appendaged calyptra development in Fontinalis

Abstract

Some species of Fontinalis produce a calyptra which splits below the point of insertion of adjacent archegonia. Therefore accessory archegonia are incorporated into the aerial calyptra. This is especially evident in F. squamosa and less so in species with few archegonia per perichaetium such as F. dalecarlica.     

Antagonistic interactions between fungal pathogens and phylloplane fungi of guava

Dominant phylloplane fungi of guava (Psidium guajava L.) were screened for their antagonistic activities against the two pathogens,Colletotrichum gloeosporioides andPestalotia psidii, bothin vitro andin vivo. Culture filtrates ofAspergillus niger, Fusarium oxysporum andPenicillium citrinum caused more than 50% growth inhibition ofC. gloeosporioides. Filtrates ofCephalosporium roseo-griseum andF. oxysporum were most effective in reducing the growth ofP. psidii. Volatiles produced from the cultures ofA. niger, F. oxysporum, P. citrinum andP. oxalicum inhibited the growth ofC. gloeosporioides, whereas volatiles fromC. roseo-griseum, F. oxysporum andTrichoderma harzianum inhibited the growth ofP. psidii. The inhibitory effect of volatiles decreased with increase in incubation time. In general, the maximum effect of volatiles was noticed after 48 h incubation. Different grades of colony interactions in dual cultures were recognised between the two pathogens and the phylloplane fungi examined. Maximum inhibition ofC. gloeosporioides was caused byAureobasidium pullulans, Cladosporium cladosporioides, epicoccum purpurascens, F. oxysporum andMyrothecium roridum, whereasAspergillus terreus, C. roseo-griseum andP. oxalicum significantly reduced the growth ofP. psidii. Application of a spore suspension of each test fungus inhibited lesion development of guava leaves caused by the test pathogensin vitro. Inhibition was more pronounced when the spore concentration was increased.A. pullulans, C. cladosporioides, E. purpurascens, F. oxysporum, andT. harzianum were found to be strongly antagonistic toC. gloeosporioides. A. niger, A. terreus, C. roseo-grisem andT. harzianum were strongly antagonistic toP. psidii.     

Phenolic and mineral content of leaves influences decomposition in European forest ecosystems

Summary Factors influencing decomposition in European forests growing on different soils were studied in stands dominated by the European beechFagus sylvatica L. Phenolic contents of freshly fallen leaves ofF. sylvatica growing on nutrient-poor soils (acid sandy soil) were higher than those of similar leaves on nutrient-rich soils (calcareous mull soil). Analysis of fallen leaves of different ages showed rapid decay of phenolics during the first winter on the ground. After 1 year the phenolic content of leaves ofF. sylvatica growing on nutrient-poor soils was still twice as high as in similar leaves on nutrient-rich soils. Field and laboratory experiments showed that a major decomposer (Oniscus asellus, Isopoda) preferred leaves from trees on nutrient-rich soils. Mineral contents of leaves ofF. sylvatica growing on different soils differed: on rich soils leaves had higher contents of Ca, Mg, Na, and K. These elements are important nutrients for decomposers. The distribution of major decomposers reflects the mineral content of their diet, which in turn reflects soil type. Different rates of leaf turnover and nutrient turnover in different forest ecosystems (even when the same tree species is dominant) are due to the decomposing system, which is influenced by the phenolic and mineral contents of the leaves.     

Moniliformin production byFusarium species isolated from Argentinian corn

Forty-one isolates ofFusarium obtained from the main Argentinian corn production area were tested for their ability to produce moniliformin. One of 22 isolates ofF. moniliforme, 2/10 of F.proliferatum and 3/9 ofF. subglutinans, produced moniliformin in a range between 0,3 to 2,7 mg/g. These data represent the first report of the production of moniliformin byFusarium species from section Liseola in Argentina.     

Incidence ofFusaria and occurrence of selected Fusarium mycotoxins on Lolium spp. in Germany

Test plantings with varieties ofLolium multiflorum andL perenne were harvested 4 to 7 times a year in 1991 and 1992. Samples were checked for the presence ofFusaria, the mycotoxins zearalenone, T-2 toxin, and diacetoxyscirpenol (DAS). Spectrum of species and the incidence ofFusaria and fusariotoxins are discussed in relation to the influencing factors site, variety ofLolium, harvesting time and year. Depending on these factors, 41 % to 100 % of the samples wereFusarium positive. Differences in infestation with Fusarium among varieties ofLolium perenne were dependent on location and did not correlate with yield. The six species ofFusarium pathogenic toLolium spp. (F. graminearum, F. culmorum, F. avenaceum, F. oxysporum, F. solani, and F. acuminatum) totaled 35.7 % of all the isolated strains. 14 species could be isolated fromLolium samples (descending frequency):F. culmorum, F. sambucinum, F. equiseti, F. acuminatum, F. semitectum, F. oxysporum, F. subglutinans, F. avenaceum, F. sporotrichioides, F. proliferatum, F. tricinctum, F. anthophilum, F. dimerum and F. graminearum. For the detection ofFusaria a promising new immunological method is presented. It is based on the genus specific production of exopolysaccharides byFusarium species. Mycotoxin contents in grass ranged from 0.01 to 4.75 ppm for zearalenone with 67 % positive samples and 0.3 % samples above 1 ppm, 0.04 to 2.78 ppm for T-2 toxin with 25 % positive samples and 2.8 % samples above 1 ppm, and 0.003 to 0.06 for DAS with 21.6 % positive samples. In silages, no T-2 toxin was detectable. IsolatedFusarium strains were checked for the ability to produce the mycotoxins zearalenone, T-2 toxin and DAS in culture. Most of the strains were positive for at least one of the toxins.     

Theories on adaptations to high light intensity in the aquatic moss Fontinalis

Abstract

Fontinalis antipyretica, collected from a cold stream in bright sunlight, served as a model for adaptations of Fontinalis to sun and shade. Sun leaves produced red pigments and had less chlorophyll, greater specific leaf weight, and less specific leaf area than shade leaves. The chlorophyll a/b ratio was not significantly different under high and low light conditions. Except for the relatively constant a/b ratio, Fontinalis behaved like higher plants in its sun/shade differences.     

Xenomeris saccifolii and gibbera sphyrospermi,new tropical species of the Venturiaceae (Fungi,Pleosporales)

Xenomeris saccifolii is described from leaves ofSaccifolium bandeirae (Gentianales, Saccifoliaceae);Gibbera sphyrospermi is described from fruit ofSphyrospermum cordifolium (Ericales, Ericaceae). The anamorph ofG. sphyrospermi is presumed to be a species ofStigmina. The concept ofStigmina is expanded to include species with unicellular conidia produced on branched conidiophores.     

A new species of Lithachne (Poaceae: Bambusoideae) and remarks on its sleep movements

A new species of herbaceous bambusoid grass,Lithachne humilis, is described from Honduras and compared with the three other species known in the genus. As in many other grasses of this alliance, the leaves ofL. humilis exhibit so-called “sleep movements” at night. The diurnal and nocturnal positions of its leaves are compared to those ofStrephium distichophyllum. The leaves of the new species and of two of the others inLithachne hang down vertically at night, while those ofStrephium fold upward, which is the usual position assumed by leaves of bambusoid grasses during the night.