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Tomato Seedlings (tomato + seedling)

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Life Sciences100%

Selected Abstracts

Biocontrol and Plant Pathogenic Fusarium oxysporum -Induced Changes in Phenolic Compounds in Tomato Leaves and Roots

JOURNAL OF PHYTOPATHOLOGY, Issue 7-8 2007
Y. Panina
Abstract The biocontrol fungus Fusarium oxysporum strain CS-20 was previously shown to reduce the incidence of Fusarium wilt of tomato through an uncharacterized host-mediated response. As phenolic compounds are involved in the defence response of tomato to pathogens and other stressors, this work was undertaken to determine whether biocontrol strains induced changes in phenolic compounds in leaves and roots of tomato seedlings in the presence and absence of pathogenic F. oxysporum f. sp. lycopersici. Roots of intact tomato seedlings were placed in water or aqueous fungal spore suspensions. Two biocontrol F. oxysporum strains [CS-20 (host-mediated mechanism) and 85SK-1 (control mechanism unknown)] and two plant pathogenic strains of F. oxysporum f. sp. lycopersici Race 1 were used. After 24 or 72 h exposure, phenolic compounds were extracted from leaves and roots before identification by HPLC. There were significant qualitative and quantitative differences between the two sampling times. Compared with the control treatment, strain CS-20 significantly altered (usually increasing) the ferulic, caffeic and vanillic acid contents, and concentrations once unidentified phenolic compounds recovered from leaves and roots. In another experiment, tomato seedlings growing in sterile sand were drenched with spores of strain CS-20 the day before treating them with varying concentrations of spores of the pathogen for 24 or 72 h. The amount of pathogen present did not significantly affect the plant phenolic response to the presence of strain CS-20. This work demonstrates that tomato responds within 24 h to the presence of the biocontrol strain CS-20 by alterations in secondary metabolism that are typical of resistance responses in tomato. [source]

Comparison of Suppressiveness of Vermicomposts Produced from Animal Manures and Sewage Sludge against Phytophthora nicotianae Breda de Haan var. nicotianae

JOURNAL OF PHYTOPATHOLOGY, Issue 2 2001
M. Szczech
The degrees of suppression produced by vermicomposts produced from cattle manure, sheep manure or horse manure and by vermicomposts produced from sewage sludge were compared in greenhouse experiments. The effect of these vermicomposts on the growth and infection of tomato seedlings by Phytophthora nicotianae var. nicotianae was studied. The density of the pathogen and the number of micro-organisms in container media amended with vermicomposts were also analysed. The vermicomposts produced from animal manure significantly reduced the infection of tomato seedlings by the pathogen. The density of P. nicotianae in media which included these vermicomposts was similar to that in infested peat substrate (control treatment). The vermicomposts from sewage sludge did not protect tomato seedlings against P. nicotianae. They also significantly inhibited growth of the plants as well as decreasing the density of the pathogen in container media. In general the vermicomposts had no effect on total number of micro-organisms in potting media compared with control. They only had higher levels of actinomycetes but this did not appear to correspond with their ability to suppress the pathogen. Ein Vergleich der Suppressivität von Vermikomposten aus tierischem Mist bzw. Klärschlamm gegenüber Phytophthora nicotianae Breda de Haan var. nicotianae In Gewächshausversuchen wurde die Suppressivität von Vermikomposten, die aus Rinder-, Schaf- bzw. Pferdemist hergestellt worden waren, mit solchen, die aus Klärschlamm gewonnen wurden, verglichen. Der Einfluss dieser Komposttypen auf die Infektion von Tomatensämlingen mit Phytophthora nicotianae var. nicotianae wurde untersucht. Außerdem wurden sowohl die Inokulumdichte als auch eine Gesamtkeimzahl der mit den Komposten versetzten Topferden ermittelt. Die aus tierischem Mist hergestellten Vermikomposte reduzierten die Infektion der Tomatensämlinge mit dem Pathogen signifikant. Die P. nicotianae -Dichte in Topferden versetzt mit diesen Vermikomposten war vergleichbar mit inokuliertem Torfsubstrat (die Kontrolle). Die Vermikomposte aus Klärschlamm lieferten den Tomatensämlingen keinen Schutz gegen P. nicotianae. Außerdem verursachten sie eine signifikante Wachstumshemmung der Pflanzen und reduzierten zusätzlich die P. nicotianae -Dichte im Topfsubstrat. Im allgemein wurde die Gesamtzahl an Mikroorganismen in den Topfsubstraten durch die Vermikomposte nicht beeinflusst. Die Actinomyceten-Populationen nahmen zu, eine Beobachtung, die jedoch keine Korrelation zu deren Pathogensuppressivität hatte. [source]

Evaluation of different RNA extraction methods for small quantities of plant tissue: Combined effects of reagent type and homogenization procedure on RNA quality-integrity and yield

PHYSIOLOGIA PLANTARUM, Issue 1 2006
Mary Portillo
Highly sensitive techniques for transcriptome analysis, such as microarrays, complementary DNA-amplified fragment length polymorphisms (cDNA-AFLPs), and others currently used in functional genomics require a high RNA quality and integrity, as well as reproducibility among extractions of replicates from the same tissue. There are, however, few technical papers comparing different homogenization techniques and reagents to extract RNA from small quantities of plant tissue. We extracted RNA from tomato seedlings with the three different commercial reagents TRIZOL LS®, TRIZOL®, and TRI Reagent® in combination with pulverization, homogenization-maceration in a mortar, and homogenization with mild vibration plus glass beads, and evaluated total RNA integrity-quality and yield. Pulverization under liquid nitrogen combined with TRIZOL LS® as extraction reagent and homogenization-maceration in mortar with TRI Reagent®, are the procedures that rendered higher RNA yield, integrity and quality, as well as reproducibility among independent RNA extractions. In contrast, short mild vibration pulses (4500 r.p.m. for 5 s) mixed with glass beads, rendered low extraction efficiency and caused, in most cases, partial RNA degradation. [source]