Comparative paleohistology in osteoderms of Pleistocene Panochthus sp. Burmeister, 1886 and Neuryurus sp. (Xenarthra,Glyptodontidae)

Xenarthran osteoderms are integumentary bones with high fossilization potential presenting a high degree of morphological and histological diversity. Here, new data on the osteoderms histology of two glyptodonts, Panochthus and Neuryurus are presented. The poor spatial organization of the mineralized fibers and a large trabecular area in the middle zone identified in Neuryurus indicate a different bone pattern than the one found in Panochthus, which is mainly characterized by a middle zone with less spongiosa. Through the Bone Profiler program, the degree of compactness of the specimens was obtained, with about 70% for Neuryurus sp. and approximately 90% for Panochthus sp., showing the difference in bone pattern. These values confirm the visible difference in the histological patterns of these taxa, especially in the middle zone. This work demonstrates the microstructural variation studied in osteoderms and shows the importance of paleohistology as a starting point for a better understanding of extinct taxa.     

Management of Fusarium oxysporum f. sp. lycopersici and root-knot nematode disease complex in tomato by use of antagonistic fungi,plant resistance and neem

Simultaneous infestation with root-knot nematodes (RKN) and Fusarium oxysporum f. sp. lycopersici (FOL) leads to formation of a disease complex that increases crop losses than effect of either RKN or FOL. In this study a management programme involving plant resistance, biological control agents, and neem was carried out to manage RKN and fusarium wilt disease complex. The biological control agents were Purpureocillium lilacinum (PL) and Trichoderma harzianum (TH) while the RKN was Meloidogyne javanica. In vitro dual culture plates were set up to test the interaction of biological control agents and FOL. Greenhouse experiments were conducted using two tomato cultivars Rambo F1 and Prostar F1. The treatments were; PL, TH, PL–TH, neem, PL neem, TH neem, and PL–TH neem. Each treatment was replicated four times and the treatments set up in a randomised complete block design in the greenhouse. Inhibition of FOL mycelial growth by TH and PL was 51.9%, and 44% respectively by the ninth day in vitro culture plates. In the cultivar, Prostar F1, the treatments PL–TH, PL, and TH in the presence or absence of neem had a FOL disease severity score significantly lower than the untreated control. Host resistance sufficed to prevent infection of Rambo F1 with FOL. The treatments PL–TH, PL and TH reduced FOL propagules and M. javanica juveniles in the roots and performed even better when combined with neem in both tomato cultivars. Therefore, a host that is resistant combined with biological control agents and organic amendments can be used in the management of RKN and FOL in tomato production.     

Hermaphroditism,gonochorism, and asexual reproduction in Cassiopea sp.—an immigrant in the islands of Hawai'i

Summary

Two populations of the conspicuous, semi-sessile medusae of the rhizostome genus Cassiopea, both morphologically similar to Cassiopea andromeda from the Red Sea and Indopacific, were recently studied on Oahu (Hawai'i), one from a sheltered saltwater pond (the Hilton Lagoon) next to Ala Wai Harbor, Honolulu, and the second from the canals of a fish farm near Kahuku on NE Oahu. Gonad differentiation, checked in 1998, and again in 1999 and 2000, was unexpectedly different in medusae from these two locations. Contrary to all earlier reports and personal observations of strict gonochorism in C. andromeda, the majority of the Hilton Lagoon medusae collected in 1998 were hermaphroditic with female and male parts intermingling in the gonads. This is an exceptional case in scyphozoans. However, this hermaphroditic condition, which was observed again in 1999, was not stable over time. All six medusae taken from the same lagoon in 2000 were distinctly gonochoristic; four were males, and two were females brooding egg masses on the oral disk. Planula larvae hatching in the laboratory were successfully reared to the scyphopolyp stage. By contrast, medusae sampled from the population were all males in 1998, 1999, and 2000. Polyps were found abundantly on dark, deteriorating leaves of the Red Mangrove, occasionally on other plant remnants, and on discarded plastic materials in the canals. The polyps propagated asexually both by strobilation of ephyrae and by production of motile, larva-like buds that settled to form additional polyps. We speculate on a clonal origin of this male population. Asexually formed propagules were induced to form polyps by exposure to either the peptide Z-GPGGPA or biogenic substrata as has been shown before in other Cassiopea species. The serine/threonine protein phosphatase inhibitor cantharidin stimulated bud development too, but interfered strongly with pattern formation, polarity, and the sequence and timing of morphogenetic events. It did not induce typical bud-to-polyp metamorphosis.     

A linkage map of diploid Avena based on RFLP loci and a locus conferring resistance to nine isolates of Puccinia coronata var. ‘avenae’

An F₂ oat population was produced by crossing the diploid (n=7) species Avena strigosa (CI 3815) with A. wiestii (CI 1994), resistant and susceptible, respectively, to 40 isolates of Puccinia coronata, the causal agent of crown rust. Eighty-eight F₂ individuals were used to construct an RFLP linkage map representing the A genome of cultivated hexaploid oat. Two hundred and eight RFLP loci have been placed into 10 linkage groups. This map covers 2416 cM, with an average of 12 cM between RFLP loci. Eighty-eight F₃ lines, derived from F₂ individuals used to construct the map, were screened for resistance to 9 isolates of P. coronata. One locus, Pca, was found to confer a dominant resistance phenotype to isolates 203, 258, 263, 264B, 290, 298, 325A, and 345. Pca also conferred resistance to isolate 276; however, an unlinked second gene may also be involved.Journal Paper No. 15143 of the Iowa Agriculture and Home Economics Experiment Station, Ames, Iowa. Project No. 3134 and 2447     

Subcellular localization of β-1,3-glucanase in Puccinia recondita f.sp. tritici-infected wheat leaves

An antiserum raised against the purified 33-kDa β-1,3-glucanase of wheat (Triticum aestivum L.) was employed to investigate the ultrastructural localization of the enzyme in wheat leaves infected with Puccinia recondita Rob. ex Desm. f.sp. tritici Eriks. and Henn. using a post-embedding immunogold labelling technique. In both compatible and incompatible interactions, β-1,3-glucanase was detected in the host plasmalemma and in the domain of the host cell wall near the plasmalemma of the mesophyll cells, but higher concentrations of the enzyme were detected in infected resistant wheat leaves than in infected susceptible ones. β-1,3-Glucanase was also found in the secondary thickening of xylem vessels and in the walls of guard cells, epidermal cells and phloem elements, while no labelling was observed in host organelles, viz. vacuoles, mitochondria, endoplasmic reticulum, Golgi bodies, nuclei and chloroplasts. A low concentration of the enzyme was detected on the intercellular hyphal wall and in the hyphal cytoplasm. In the compatible interaction, β-1,3-glucanase was demonstrated to accumulate predominantly in the haustorial wall and extrahaustorial matrix. In the incompatible interaction, strong labelling for β-1,3-glucanase was found in host cell wall appositions, in the extracellular matrix in the intercellular space, and in electron-dense structures of host origin which occurred in the incompatible interaction only. Received: 22 July 1997 / Accepted: 16 August 1997     

Growth responses and lignin production in cell suspensions of Pinus elliottii ‘elicited’ by chitin,chitosan or mycelium of Cronartium quercum f.sp. fusiforme

Incubation of suspension-cultured slash pine (Pinus elliotti Engelm.) cells with living mycelial plugs or homogenized, washed and autoclaved mycelium of Cronartium quercum f.sp. fusiforme led to rapid clouding of the medium and visible inhibition of cell growth with only a slight increase in cell mortality. Purified chitin elicited similar changes in cloudiness and growth. Chitin treatment concentrations of up to 1 mg ml^-1 showed only slight changes in viability over several days (as with the mycelium and mycelial extract). In contrast, chitosan concentrations of as low as 60 gml^-1 showed cell mortality and browning, with a complete hypersensitive response and over 90% cell death occurring within 48 h at between 180 and 270 ml^-1 chitosan amendment. Phloroglucinol staining showed the presence of lignin-like compounds in the medium and lignin-like compounds were elevated in the cell walls of the chitin, chitosan and mycelium elicited suspension cultures as compared to controls.     

Efflux und Transport von Cl− und Rb+ in Maiswurzeln. Wirkung von Außenkonzentration,Ca++, EDTA und IES

Summary The efflux of ³⁶Cl and ⁸⁶Rb and the fluxes of these ions into the xylem were investigated using the device shown in Fig. 1.Efflux of ³⁶Cl is stimulated by external KCl while transport into the xylem is inhibited. Stimulation of the efflux appears to be stronger than inhibition of the transport.The stimulation of the efflux of ³⁶Cl was also observed with roots of intact seedlings.Assuming that the mode of transfer of Cl^– into the xylem (flux 3, Fig. 8) is diffusion exhibiting a linear isotherm (Luttge and Laties, 1966), these results suggest that the primary action of external salts is on the efflux across the plasma-lemma (Weigl, 1967, 1968). We were unable, however, to find a linear relationship between concentration and rate of chloride transport to the shoots of intact seedlings.With respect to the mode of ion transfer to the xylem (Weigl and Lüttge, 1965; Luttge and Laties, 1966) we have to be aware of the following facts:A linear isotherm cannot be taken to signify diffusive permeation (Torii and Laties, 1966; Luttge and Laties, 1966). If the Michaelis constant is extremely high relative to the ion concentration, the relationship between the ion concentration and the rate of a metabolic or mediated transport approaches linearity.The isotherm of the transport into the xylem may primarily reflect the difference of two large fluxes (4 and 5; Fig. 8).The transport data of Luttge and Laties (1966) need not be presented as a straight line (Fig. 6).If at high external ion concentrations the ratio of the ion concentration in the exudation sap to the external ion concentration approaches unity, diffusive permeation into the stele is still not proved to be the mode of migration, since at high stelar ion concentration flux 6 tends to become equal to flux 3.Considerations on radial ion transfer into the xylem depend on contemporary knowledge of the location of transport systems. Cl^–-uptake into root tips (2 mm) from solutions of 1–10 mM KCl did not exhibit a linear isotherm. These results are unpublished since the discrepancy to the results of Torii and Laties (1966) may be due to a higher content of vacuoles in our root tips. We feel it unlikely, however, that a linear isotherm of Cl^–-uptake into root tips is adequately explained by assuming that it is due to a lack of vacuoles while the sensibility to inhibitors is assumed to be due to the presence of vacuoles in root tips.Transport of Cl^– into the xylem is susceptible to inhibitors of oxydative phosphorylation, suggesting that this process, even at high external ion concentrations, is dependent on metabolic energy in contrast to the passive efflux from the cortical cells across the plasmalemma into the environment of the root. The precise location of the metabolic step(s) on the pathway of ions from the environment of the root to the xylem is unknown.The observed effects of Ca⁺⁺, EDTA and IAA may be considered in relation to the theory that auxin exerts its influence on growth by altering the diffusion potential across cell membranes (Brauner and Diemer, 1967). Growth is susceptible to the effect of Ca⁺⁺ and EDTA (Adamson, 1962; Setterfield, 1963; Thimann, 1963). Nevertheless, since IAA exerts no influence on ion fluxes in corn roots, it is not clear whether IAA really exerts its influence on growth by altering the diffusion potential across plant cell membranes. We might be dealing with occasional effects of secondary importance.     

Stoffwechsel von Isoflavonen und Cumöstanen in Zell- und Callussuspensionskulturen von Phaseolus aureus Roxb.

Summary The isoflavone daidzein, the coumestanes coumestrol and soyagol as well as 2,4,4-trihydroxychalcone were isolated from callus and cell suspensions of root tip tissue from Phaseolus aureus Roxb. Upon prolonged culturing callus suspensions gradually became cell suspensions, a process which was accompanied by a decrease in the accumulation of phenolics. Upon transfer of the cells into 3 different media containing -indolyl acetic acid, kinetin or -naphthalene acetic acid, a drastic increase in the amount of coumestrol was measured.The data are discussed in relation to the observed differentiation of the cultures after application of the various hormones. The cultures were shown to metabolize daidzein and other phenylpropanoid compounds. A pronounced binding of daidzein to polymeric, ethanol-insoluble material is discussed in relation to our earlier findings in isoflavone metabolism.     

Suppressiveness to Fusarium oxysporum f. sp. radicis lycopersici in re-used perlite and perlite–peat substrates in soilless tomatoes

This work reports the occurrence of suppressiveness to Fusarium oxysporum f. sp. radicis lycopersici (FORL) on recycled perlite and perlite–peat mix from closed and open soilless systems. Nine soilless systems were sampled from three different sites in Northern and Southern Italy and different parameters, including sampling site, growing period before sampling, electric conductivity of the nutrient solution, tomato cultivar, and irrigation system were considered. The effects on seed germination and FORL incidence on tomato seedlings were finally assessed with or without additional artificial inoculation of the pathogen and with or without autoclaving the samples prior to inoculation. Suppression of FORL was experimentally evaluated with a technique already adopted for rockwool. Results collected on perlite and perlite–peat confirmed the possibility to reduce FORL severity on recycled substrates. Only the composition of the substrate (perlite, perlite–peat mix) and the disinfestation did affect the incidence of FORL. Suppression of FORL was observed in not disinfected recycled perlite–peat substrates while a reduction of FORL incidence was also been recorded in disinfected and recycled perlite. Disease incidence decreased from an average ranging from 44.4% to 61.9% in new perlite to 2.5–36.3% in recycled one. Similarly disease incidence decreased from an average ranging from 35.9% to 75.2% in new perlite–peat mix to 0.4–26.4% in recycled perlite–peat mix. In conclusion the recorded data suggest the possibility to consider FORL suppression as a predictable phenomenon when recycled substrates (perlite, perlite–peat mix) are adopted.     

Description of Ulvella elegans sp. nov. and U. islandica sp. nov. (Ulvellaceae,Ulvophyceae) from Iceland – a study based on morphology of species in culture and tufA gene sequences

Two new Ulvella species, U. elegans R. Nielsen & K. Gunnarsson and U. islandica R. Nielsen & K. Gunnarsson are described. These microfilamentous marine green algae were found in the sublittoral zone in northern Iceland, epiphytic on Euthora cristata and associated with a calcareous polychaete tube, respectively. Unialgal cultures were established from field-collected material for morphological observations. In culture, Ulvella elegans was characterized by rosettes of monostromatic pseudoparenchyma consisting of radiating filaments with a margin of mutually free filaments. Each cell had one pyrenoid. Hairs were not observed. Ulvella islandica had a heterotrichous morphology, consisting of dense tufts of upright broad branches and much narrower, rhizoid-like branches. Acrochaete-type hairs occurred; these are hyaline non-septate merocytic extensions from a more or less bulbous base, which may be separated from the vegetative cell below. Most cells had one pyrenoid except for a few broad cells which had two or three. In a phylogenetic reconstruction based on the chloroplast-encoded tufA gene, the sequences for the two species were clearly distinct from any other Ulvella sequence available for this gene. Ulvella islandica was placed in a clade together with U. lens, U. wittrockii, U. reticulata and U. pseudorepens. Ulvella elegans occupied a branch deep in the phylogeny but the position was poorly supported.     

Phylogenetic relationship between different race representative populations of Fusarium oxysporum f. sp. ciceris in respect of translation elongation factor-1α, β-tubulin,and internal transcribed spacer region genes

Genetic diversity of 70 isolates of Fusarium oxysporum f. sp. ciceris originated from various states of India representing eight races causing wilt in chickpea (Cicer arietinum) was analyzed using translation elongation factor-1α (TEF-1α), β-tubulin, and internal transcribed spacer (ITS) gene regions. TEF-1α, β-tubulin, and ITS gene-specific markers produced ~720-, ~500-, and ~550-bp amplicons, respectively, in all the isolates of the pathogen. A phylogenetic tree constructed from the sequences generated in the present study along with the sequences of foreign isolates of Fusarium species available in NCBI database sharing more than 90 % nucleotide sequence similarity grouped the isolates into two major clusters. Most of the isolates of the present study showed more or less similar grouping pattern in case of the three gene sequences. Each group had the isolates representing different races as well as place of origin indicating low level of diversity among the isolates in respect of these gene sequences. Except TEF-1α, the groups generated by β-tubulin and ITS gene sequences did not correspond to the state of origin and races of the pathogen. However, the groups of TEF-1α partially corresponded to the place of origin as well as races of the pathogen. The isolates did not show any race-specific grouping patterns; however, most of the isolates representing race 1 clustered separately.     

Colonization and Biodegradation of Photo-Oxidized Low-Density Polyethylene (LDPE) by New Strains of Aspergillus sp. and Lysinibacillus sp.

The primary objective of this study was the isolation of low-density polyethylene (LDPE)-degrading microorganisms. Soil samples were obtained from an aged municipal landfill in Tehran, Iran, and enrichment culture procedures were performed using LDPE films and powder. Screening steps were conducted using linear paraffin, liquid ethylene oligomer, and LDPE powder as the sole source of carbon. Two landfill-source isolates, identified as Lysinibacillus xylanilyticus XDB9 (T) strain S7-10F and Aspergillus niger strain F1-16S, were selected as super strains. Photo-oxidation (25 days under ultraviolet [UV] irradiation) was used as a pretreatment of the LDPE samples without pro-oxidant additives. The PE biodegradation process was performed for 56 days in a liquid mineral medium using UV-irradiated pure LDPE films without pro-oxidant additives in the presence of the bacterial isolate, the fungal isolate, and the mixture of the two isolates. The process was monitored by measuring the fungal biomass, the bacterial growth, and the pH of the medium. During the process, the fungal biomass and the bacterial growth increased, and the pH of the medium decreased, which suggests the utilization of the preoxidized PE by the selected isolates as the sole source of carbon. Carbonyl and double bond indices exhibited the highest amount of decrement and increment, respectively, in the presence of the fungal isolate, and the lowest indices were obtained from the treatment of a mixture of both fungal and bacterial isolates. Fourier transform infrared (FT-IR), x-ray diffraction (XRD), and scanning electron microscopy (SEM) analyses showed that the selected isolates modified and colonized preoxidized pure LDPE films without pro-oxidant additives.     

Production, Characterization, and Properties of β-Glucosidase and β-Xylosidase from a Strain of Aureobasidium sp.

-Glucosidase and -xylosidase production by a yeastlike Aureobasidium sp. was carried out during solid-state and submerged fermentation using different carbon sources and crude enzymes were characterized. -Glucosidase and -xylosidase exhibited optimum activities at pH 2.0–2.5 and 3.0, respectively. These enzymes had the maximum activities at 65°C and were stable in a wide pH range and at high temperatures.     

Strain-specific and recessive QTLs involved in the control of partial resistance to Fusarium oxysporum f. sp. melonis race 1.2 in a recombinant inbred line population of melon

Fusarium oxysporum f. sp. melonis (FOM) causes serious economic losses in melon (Cucumis melo L.). Two dominant resistance genes have been identified, Fom-1 and Fom-2, which provide resistance to races 0 and 2 and races 0 and 1, respectively, however FOM race 1.2 overcomes these resistance genes. A partial resistance to FOM race 1.2 that has been found in some Far East accessions is under polygenic control. A genetic map of melon was constructed to tag FOM race 1.2 resistance with DNA markers on a recombinant inbred line population derived from a cross between resistant (Isabelle) and susceptible (cv. Védrantais) lines. Artificial root inoculations on plantlets of this population using two strains, one that causes wilting (FOM 1.2w) and one that causes yellowing (FOM 1.2y), resulted in phenotypic and genotypic data that enabled the identification of nine quantitative trait loci (QTLs). These QTLs were detected on five linkage groups by composite interval mapping and explained between 41.9% and 66.4% of the total variation. Four digenic epistatic interactions involving seven loci were detected and increased the total phenotypic variation that was explained. Co-localizations between QTLs and resistance gene homologs or resistance genes, such as Fom-2 and Vat, were observed. A strain-specific QTL was detected, and some QTLs appeared to be recessive.     

Evolutionary relationships between Fusarium oxysporum f. sp. lycopersici and F. oxysporum f. sp. radicis-lycopersici isolates inferred from mating type, elongation factor-1α and exopolygalacturonase sequences

Fusarium oxysporum is a ubiquitous species complex of soilborne plant pathogens that comprises many different formae speciales, each characterized by a high degree of host specificity. In this study, the evolutionary relationships between different isolates of the F. oxysporum species complex have been examined, with a special emphasis on the formae speciales lycopersici and radicis-lycopersici, sharing tomato as host while causing different symptoms. Phylogenetic analyses of partial sequences of a housekeeping gene, the elongation factor-1α (EF-1α) gene, and a gene encoding a pathogenicity trait, the exopolygalacturonase (pgx4) gene, were conducted on a worldwide collection of F. oxysporum strains representing the most frequently observed vegetative compatibility groups of these formae speciales. Based on the reconstructed phylogenies, multiple evolutionary lineages were found for both formae speciales. However, different tree topologies and statistical parameters were obtained for the cladograms as several strains switched from one cluster to another depending on the locus that was used to infer the phylogeny. In addition, mating type analysis showed a mixed distribution of the MAT1-1 and MAT1-2 alleles in the F. oxysporum species complex, irrespective of the geographic origin of the tested isolates. This observation, as well as the topological conflicts that were detected between EF-1α and pgx4, are discussed in relation to the evolutionary history of the F. oxysporum species complex.     

Interaction of endophytic diazotrophic bacteria and Fusarium oxysporum f. sp. cubense on plantlets of banana ‘Maça’

The objective of this work was to evaluate the effect of endophytic diazotrophic bacteria Herbaspirillum and Burkholderia on the Fusarium oxysporum f. sp. cubense (Foc) establishment and on the plantlets growth of the ‘Maçã’ banana (Musa spp., group ABB). Two assays were carried out in a greenhouse at the National Center of Tropical Agroindustry in Fortaleza city, Ceará State (Brazil), using randomized block designs in the factorial arrangements 4?×?2 and 8?×?2. On the first trial plantlets were inoculated with the Burkholderia sp. AB202; Herbaspirillum sp., BA227, both of strains and controls bacteria, with and without Foc and cultivated in pots filled with an autoclaved mixture of washed sand and vermiculite (ratio 3:2 v v^?1), during 4 months. On a second assay, plants were subjected to following conditions: absence and presence of strains AB202, AB213 (Burkholderia spp.), BA227, BA234 (Herbaspirillum-like), AB202 plus BA227, AB213 plus BA234, the mixture of the four bacterial strain, absence and presence of the Foc; and cultivated in pots filled with autoclaved Haplic Arenosol, during 2 months. The plant association with diazotrophs and the Foc was confirmed, and factors interacted significantly on the most probable number of bacteria and the colony forming units of the pathogen on roots and plant rhizomes. The potential of the endophytes on the inhibition of Foc propagate units and on the plant growth promotion was demonstrated. The higher biomass was observed four and 2 months after plant inoculation with AB202 and BA234. Results showed that these endophytes may be used as potential biofertilizer and biocontrol agents.     

The genetic of pathogenicity of Puccinia striiformis f. sp. tritici the cause’s agent of wheat yellow rust disease in Iran

Wheat yellow (stripe) rust disease is one of the important and prevalent diseases of wheat in the world. In this study, 37 isolates of yellow rust diseased from most important wheat-growing areas in Iran has been collected, and the genetic of pathogenesis and race analysis as well as abundance per cent of the disease for genes under study with using 45 differential and isogenic lines together with susceptible Bolani were applied. The experimental materials with the spores of each isolate that were inoculated in the seedling stage separately and after 17?days scored by McNeal et al. method. Also the physiologic races responsible for the disease determined according to Johnson and his colleagues method. The results showed that the race 166E254A?+?Yr27+ with 62.50% of pathogenesis was the most aggressive race from Torogh (Mashhad) 6, and the race 6E134A+ with 33.34% of pathogenesis factor was the weak race from Zarghan1. According to these results, for all the plants containing genes Yr2, Yr6, Yr7, Yr9, Yr18, YrA virulence was observed from all isolates. For the plants contained with genes Yr1, Yr4, Yr5, Yr10, Yr15, YrSU were effective against all isolates. Genes Yr3, Yr24, YrSP with low per cent of pathogenesis (2.7) and genes Yr2, Yr6, Yr7, Yr9, Yr18, Yr4 with high per cent (100) and Yr17 (97.3) have been identified.