Induced systemic resistance against systemic viruses : a feasible approach?

Induction of resistance to plant viruses causing localized infections has been widely used to study HR and SAR mechanisms. However, in Nature true virus diseases are produced by viruses able to systemize in the plant and SAR is scarcely effective against them. Thus, a more successful strategy relays in the induction of resistance against both the virus and its vector. In this work, using the pathosystem bean common mosaic virus (BCMV)-Phaseolus vulgaris we made attempts of inducing resistance separately to both the pathogen and the aphid vector Myzus persicae, with the aim of dissecting the two resistance levels inducible with the most used chemical elicitors. Results showed that BTH and chitosan are able to reduce the infection degree in BCMV mechanically inoculated plants, however not preventing the infection. On the other hand, chitosan and 2-isobutyric acid (IBA), applied as root-drench, could reduce aphid population by half. Therefore, combining the two effects and using chitosan, partially effective against both the virus and the vector, it could be possible to raise an acceptable resistance level in the field, where BCMV is actively spread by aphids. To verify this hypothesis, experimental transmission with viruliferous aphids in chitosan and IBA treated plants are now in progress

The product of the rice myb7 unspliced mRNA dimerizes with the maize leucine-zipper opaque2 and stimulates its activity in transient expression assay

myb7 mRNA is present in rice in spliced and unspliced forms, splicing being enhanced by anoxia. The protein (Mybleu) encoded by the unspliced mRNA is composed of an incomplete Myb domain followed by a leucine zipper; however, it lacks canonical sequences for DNA binding, transcriptional activation, and nuclear localization. We show here that in transiently transformed tobacco protoplasts, Mybleu is able to enhance the transcriptional activity of the maize leucine zipper Opaque2 on its target b32 promoter. The Mybleu transactivation effect is strictly dependent on the presence of Opaque2 and is driven by Mybleu-Opaque2 heterodimers. Mybleu is located in the nucleus, both in rice and in transformed tobacco protoplasts. In rice, the protein is expressed in regions corresponding to undifferentiated cells of roots and coleoptiles. Therefore, myb7 mRNA encodes, depending on its splicing, two transcription factors belonging to separate classes. One of them, Myblue, has novel structural characteristics, suggesting the existence of new mechanisms acting in the activation of transcription. -------------------------------------------------------------------------------

Insight into composition of bioactive phenolic compounds in leaves and flowers of green and purple basil

Basil (Ocimum basilicum L.) is a culinary, medicinal, and ornamental plant appreciated for its antioxidant properties, mainly attributed to high content of rosmarinic acid. This species also includes purple varieties, characterized by the accumulation of anthocyanins in leaves and flowers. In this work, we compared the main morphological characteristics, the antioxidant capacity and the chemical composition in leaves, flowers, and corollas of green (\u2018Italiano Classico\u2019) and purple (\u2018Red Rubin\u2019 and \u2018Dark Opal\u2019) basil varieties. The LC-ESI-MS/MS analysis of individual compounds allowed quantifying 17 (poly)phenolic acids and 18 flavonoids, differently accumulated in leaves and flowers of the three varieties. The study revealed that in addition to rosmarinic acid, basil contains several members of the salvianolic acid family, only scarcely descripted in this species, as well as, especially in flowers, simple phenolic acids, such as 4-hydroxybenzoic acid and salvianic acid A. Moreover, the study revealed that purple leaves mainly contain highly acylated anthocyanins, while purple flowers accumulate anthocyanins with low degree of decoration. Overall, this study provides new biochemical information about the presence of not yet characterized bioactive compounds in basil that could contribute to boosting the use of this crop and to gaining new knowledge about the roles of these compounds in plant physiology

A cytological and ultrastructural study on the maturation and germination of oospores of Plasmopara viticola from overwintering vine leaves

Observations on cytological and ultrastructural changes in Plasmopara viticola oospores were carried out during the overwintering period. Three types of oospores were observed. Type I, characterized by a thin inner oospore wall (IOW), large lipid globules and two nuclei, was recovered only in samples collected in October. These oospores were considered to be immature. Maturation occurred during November and involved a noticeable increase in thickness of the IOW, fusion of nuclei, formation of an ooplast and break up of large lipid globules into smaller ones (type II oospores). A few oospores (type III) showed abnormal organization with very large lipid globules and less frequently discernible nuclei. IOW solubilization, dissolution of the ooplast and lipid globules and nuclear division were the first detectable events during oospore germination. Germinating oospores produce a germ tube which was terminated by a sporangium. In its young stage, the sporangium had a thick wall and an unusual multi-layered membrane. During this phase, nuclear divisions took place in the sporangium. While sporangium development progressed, the ribosome density in the cytoplasm decreased and mitochondria, initially roundish with evident cristae, became their usual tubular profile. The plasma membrane had a typical structure and storage organelles, such as finger print vacuoles and lipid globules, became more numerous in the cytoplasm. Larger vacuoles contained the flagella of differentiating zoospores.Observations on cytological and ultrastructural changes in Plasmopara viticola oospores were carried out during the overwintering period. Three types of oospores were observed. Type I, characterized by a thin inner oospore wall (IOW), large lipid globules and two nuclei, was recovered only in samples collected in October. These oospores were considered to be immature. Maturation occurred during November and involved a noticeable increase in thickness of the IOW, fusion of nuclei, formation of an ooplast and break up of large lipid globules into smaller ones (type II oospores). A few oospores (type III) showed abnormal organization with very large lipid globules and less frequently discernible nuclei. IOW solubilization, dissolution of the ooplast and lipid globules and nuclear division were the first detectable events during oospore germination. Germinating oospores produce a germ tube which was terminated by a sporangium. In its young stage, the sporangium had a thick wall and an unusual multi-layered membrane. During this phase, nuclear divisions took place in the sporangium. While sporangium development progressed, the ribosome density in the cytoplasm decreased and mitochondria, initially roundish with evident cristae, became their usual tubular profile. The plasma membrane had a typical structure and storage organelles, such as finger print vacuoles and lipid globules, became more numerous in the cytoplasm. Larger vacuoles contained the flagella of differentiating zoospores

Nonequilibrium critical dynamics of the bi-dimensional ±J\pm J Ising model

The $\pm J$ Ising model is a simple frustrated spin model, where the exchange couplings independently take the discrete value $-J$ with probability $p$ and $+J$ with probability $1-p$. It is especially appealing due to its connection to quantum error correcting codes. Here, we investigate the nonequilibrium critical behavior of the bi-dimensional $\pm J$ Ising model, after a quench from different initial conditions to a critical point $T_c(p)$ on the paramagnetic-ferromagnetic (PF) transition line, especially, above, below and at the multicritical Nishimori point (NP). The dynamical critical exponent $z_c$ seems to exhibit non-universal behavior for quenches above and below the NP, which is identified as a pre-asymptotic feature due to the repulsive fixed point at the NP. Whereas, for a quench directly to the NP, the dynamics reaches the asymptotic regime with $z_c \simeq 6.02(6)$. We also consider the geometrical spin clusters (of like spin signs) during the critical dynamics. Each universality class on the PF line is uniquely characterized by the stochastic Loewner evolution (SLE) with corresponding parameter $\kappa$. Moreover, for the critical quenches from the paramagnetic phase, the model, irrespective of the frustration, exhibits an emergent critical percolation topology at the large length scales.Comment: 26 pages, 10 figure

Índices de emissão de ramos em pereiras.

A elaboração de escalas de emissão de ramos em pereiras objetiva classificar os genótipos quanto a seu hábito de crescimento, as quis serão úteis para compor o índice de vigor de plantas e para a seleção de genitores em programas de melhoramento genético. Para isso, foram desenvolvidas duas escalas: a primeira, para avaliar a quantidade de emissão de ramos secundários, ou seja, os ramos originados do tronco principal da planta, composta por três classes e com notas variando entre 1 e 5, contendo desenhos e exemplos de genótipos; a segunda, para avaliar o tipo e a quantidade de ramos terciários e quaternários emitidos a partir dos ramos secundários, sendo ela composta também por três classes e notas variando de 1 a 5. Utilizando as duas tabelas, foram avaliadas duas (em alguns casos somente uma) plantas/genótipo do Banco de Germoplasma de Pereira existente na Estação Experimental de Caçador, em Caçador, SC, no ano agrícola 2012/13. As plantas ficaram sem poda e condução durante 2 anos. Exemplos de genótipos com menor emissão de ramos secundários foram os cvs. Kousui, Kikusui, Nijisseiki, Beurre d?Anjou e Doyenne du Comice; e com maior emissão os cvs. Le Conte e Md. Siebold. Quanto à menor emissão de ramos terciários e quaternários, destacaram-se os cvs. Rugosa e Md. Siebold; e com maior emissão os cvs. Feliz e Choujuurou. As escalas foram eficientes na separação dos genótipos

Classes de vigor de plantas de genótipos de pereira.

O índice de vigor de pereiras pode ser utilizado como referência em trabalhos de melhoramento genético para a seleção de genitores e também como indicativo de manejo de plantas em pomares comerciais. Para isso, foi gerado um índice de vigor utilizando informações de emissão de ramos secundários (originados do tronco principal da planta), de ramos terciários e quaternários (gerados respectivamente dos ramos secundários e terciários), além da medida da altura da planta

Construction of a synthetic infectious cDNA clone of Grapevine Algerian latent virus (GALV-Nf) and its biological activity in Nicotiana benthamiana and grapevine plants

Background: Grapevine Algerian latent virus (GALV) is a tombusvirus first isolated in 1989 from an Algerian grapevine (Vitis spp.) plant and more recently from water samples and commercial nipplefruit and statice plants. No further reports of natural GALV infections in grapevine have been published in the last two decades, and artificial inoculations of grapevine plants have not been reported. We developed and tested a synthetic GALV construct for the inoculation of Nicotiana benthamiana plants and different grapevine genotypes to investigate the ability of this virus to infect and spread systemically in different hosts. Methods: We carried out a phylogenetic analysis of all known GALV sequences and an epidemiological survey of grapevine samples to detect the virus. A GALV-Nf clone under the control of the T7 promoter was chemically synthesized based on the full-length sequence of the nipplefruit isolate GALV-Nf, the only available sequence at the time the project was conceived, and the infectious transcripts were tested in N. benthamiana plants. A GALV-Nf-based binary vector was then developed for the agroinoculation of N. benthamiana and grapevine plants. Infections were confirmed by serological and molecular analysis and the resulting ultrastructural changes were investigated in both species. Results: Sequence analysis showed that the GALV coat protein is highly conserved among diverse isolates. The first epidemiological survey of cDNAs collected from 152 grapevine plants with virus-like symptoms did not reveal the presence of GALV in any of the samples. The agroinoculation of N. benthamiana and grapevine plants with the GALV-Nf binary vector promoted efficient infections, as revealed by serological and molecular analysis. The GALV-Nf infection of grapevine plants was characterized in more detail by inoculating different cultivars, revealing distinct patterns of symptom development. Ultrastructural changes induced by GALV-Nf in N. benthamiana were similar to those induced by tombusviruses in other hosts, but the cytopathological alterations in grapevine plants were less severe. Conclusions: This is the first report describing the development of a synthetic GALV-Nf cDNA clone, its artificial transmission to grapevine plants and the resulting symptoms and cytopathological alterations

Effect of temperature on the microstructure of fat globules and the immunoglobulin-mediated interactions between fat and bacteria in natural raw milk creaming

Natural creaming of raw milk is the first step in production of Grana Padano and Parmigiano Reggiano Protected Denomination of Origin cheeses. This process decreases the fat content and plays an important role in the removal of clostridia species that may cause late-blowing defects in ripened cheeses. Partial coalescence of fat globules-that may influence fat behavior in cheese making and affect the microstructure of fat in the final cheese product-was observed at creaming temperatures higher than 22\uc2\ub0C by confocal laser scanning microscopy. The widespread practice of heating of milk at 37\uc2\ub0C before creaming at 8\uc2\ub0C resulted in important changes in the size distribution of fat globules in raw milk, potentially altering the ability of fat to entrap clostridia spores. We investigated the role of immunoglobulin classes in both the clustering of fat globules and the agglutination of Clostridium tyrobutyricum to fat globules during creaming. Immunogold labeling and transmission electron microscopy showed that IgA and IgM but not IgG were involved in both clustering and agglutination. Both vegetative cells and spores were clearly shown to agglutinate to fat droplets, a process that was suppressed by thermal denaturation of the immunoglobulins. The debacterization of raw milk through natural creaming was improved by the addition of purified immunoglobulins. Overall, these findings provide not only a better understanding of the phenomena occurring during the natural creaming but also practical insights into how the process of creaming may be optimized in cheese production plants