Plant Roots Release Small Extracellular Vesicles with Antifungal Activity

Extracellular Vesicles (EVs) play pivotal roles in cell-to-cell and inter-kingdom communication. Despite their relevant biological implications, the existence and role of plant EVs released into the environment has been unexplored. Herein, we purified round-shaped small vesicles (EVs) by differential ultracentrifugation of a sampling solution containing root exudates of hydroponically grown tomato plants. Biophysical analyses, by means of dynamic light scattering, microfluidic resistive pulse sensing and scanning electron microscopy, showed that the size of root-released EVs range in the nanometric scale (50–100 nm). Shot-gun proteomics of tomato EVs identified 179 unique proteins, several of which are known to be involved in plant-microbe interactions. In addition, the application of root-released EVs induced a significant inhibition of spore germination and of germination tube development of the plant pathogens Fusarium oxysporum, Botrytis cinerea and Alternaria alternata. Interestingly, these EVs contain several proteins involved in plant defense, suggesting that they could be new components of the plant innate immune system.

Glutathione redox state plays a key role in flower development and pollen vigour

roGFP2 measurements demonstrate that ungerminated Arabidopsis pollen grains are highly oxidized. Glutathione-deficient flowers show increased cellular oxidation with poor pollen germination/tube growth, suggesting that the reduced state underpins growth functions.

Horse chestnut pollen quality

Pollen quality of horse chestnut, expressed as pollen productivity, viability and germination was studied. Anthers of horse chestnut genotypes had pollen production from 3.66 to 5.06 x 103 pollen grains per anther, depending of genotype. Also, pollen of horse chestnut Ah1-Ah4 genotypes showed different viability (from 56 to 68%), after staining with fluorescein diacetate. Pollen germination of Ah1-Ah4 genotypes varied from 50-66% on basic medium. Inclusion of polyethylene glycol-PEG from 10%, 15% and 20% v/w increased pollen germination. The best results were achieved on medium with the largest PEG concentration. On these medium 76-91% pollen grains were germinated, depending of genotype. The best pollen quality, for all tested parameters, had genotype Ah2. Knowledge about morphology, production, viability, in vitro germination, tube growth as well as pollen: ovule ratio can be of great importance for future pollen biology studies.

PATOGENESIS HAWAR DAUN BIBIT PINUS MERKUSII YANG DISEBABKAN OLEH PESTALOTIA THEAE DI PESEMAIAN

Pathogenesis of Needle Blight of Pinus merkusii Seedlings Incited by Pestalotia theae in The Nunery. The objectives of theiudy were to clarify the mechanism by which Pestalotia theae incites the disease and the defense mechanism of the pine seedling against the attack by the pathogen. The germination tube,2.9 µm in diameter, produced by the germinating conidiospore penetrated the leaf cells via the stomata, which were wider in diameter. The pathogen was able to produce pectinolytic and cellulolytic enzymes required for the degrading of the host cell wall components. The epidermis was covered-by a thick cuticulae layer. The activity of the peroxidase reduced in the cotyledon, the primary leaf and in the secondary leaf decreased, when the seedlings were 1-2,2-3, and >3 month old.

Isolation spore production and Kochs postulates of Elsinoe pyri

Elsinoe leaf and fruit spot is a minor disease of apple and pear Very little is known of the biology and life cycle of the causal agent Elsinoe pyri The fungus was isolated from spots on apple fruit and grew very slowly on potato dextrose agar (PDA) The conditions needed for spore production were examined using different culturing media plating techniques and culture ages When small pieces of a 2 to 6weekold culture from PDA were subcultured onto corn meal agar for 2 days viable conidia were produced Conidial germination occurred between 10C and 26C with the highest germination percentage at 20C and 26C and greatest germination tube elongation at 20C At least 200 conidia per leaf were required to infect Royal Gala leaves Typical elsinoe spots were visible 6 weeks after inoculation Four months after inoculation conidia from the spots were reisolated onto PDA and grew into typical colonies of E pyri

TESTING POTENTIAL ALTERNATE METHODS OF BLOOM THINNING FOR APPLE IN VITRO

Alternate bloom thinners are needed for apple are needed to replace compounds which can no longer be used or have production system limitations. The effects of 24 chemicals selected as osmotic agents, organic acids, oils, essential oils, or potential metabolic agents and their properties of pH, electrical potential (EP) and water potential were tested in vitro on `Gala' apple pollen germination, tube growth and pistil damage. Solution concentrations of 0%, 0.25%, 0.5%, 1%, 2%, 5%, and 10% were prepared and solution pH, EP, and water potential measured. To test affects on germination, pollen was placed on agar germination media in petri dishes and then treated with 10: l of chemical solution. Percentage pollen germination and tube growth was calculated 4, 12, and 24 h after treatment. Excised pistils from forced flowers were placed on glass filter papers saturated with chemical solution. Pistil damage was visually, subjectively rated for damage indicated by discoloration 24 h after treatment. Effects of solution pH, EP and water potential on pollen germination, tube growth and pistil damage was significant with pH less than ∂4.0 or greater than ∂10.0, EP > 200mv, or water potential less than ∼4.0MPa inhibited pollen germination, growth, and killed pistils. Several chemical had apparent metabolic effects beyond the chemical effects mentioned above. In vitro tests were correlated to in vivo field tests in other studies indicating the use of pollen and pistil in vitro as a useful model for screening potential alternative thinning agents.