Investigation of long non-coding RNAs as regulatory players of grapevine response to powdery and downy mildew infection.

BACKGROUND: Long non-coding RNAs (lncRNAs) are regulatory transcripts of length > 200 nt. Owing to the rapidly progressing RNA-sequencing technologies, lncRNAs are emerging as considerable nodes in the plant antifungal defense networks. Therefore, we investigated their role in Vitis vinifera (grapevine) in response to obligate biotrophic fungal phytopathogens, Erysiphe necator (powdery mildew, PM) and Plasmopara viticola (downy mildew, DM), which impose huge agro-economic burden on grape-growers worldwide. RESULTS: Using computational approach based on RNA-seq data, 71 PM- and 83 DM-responsive V. vinifera lncRNAs were identified and comprehensively examined for their putative functional roles in plant defense response. V. vinifera protein coding sequences (CDS) were also profiled based on expression levels, and 1037 PM-responsive and 670 DM-responsive CDS were identified. Next, co-expression analysis-based functional annotation revealed their association with gene ontology (GO) terms for 'response to stress', 'response to biotic stimulus', 'immune system process', etc. Further investigation based on analysis of domains, enzyme classification, pathways enrichment, transcription factors (TFs), interactions with microRNAs (miRNAs), and real-time quantitative PCR of lncRNAs and co-expressing CDS pairs suggested their involvement in modulation of basal and specific defense responses such as: Ca2+-dependent signaling, cell wall reinforcement, reactive oxygen species metabolism, pathogenesis related proteins accumulation, phytohormonal signal transduction, and secondary metabolism. CONCLUSIONS: Overall, the identified lncRNAs provide insights into the underlying intricacy of grapevine transcriptional reprogramming/post-transcriptional regulation to delay or seize the living cell-dependent pathogen growth. Therefore, in addition to defense-responsive genes such as TFs, the identified lncRNAs can be further examined and leveraged to candidates for biotechnological improvement/breeding to enhance fungal stress resistance in this susceptible fruit crop of economic and nutritional importance.

A Role of the FUZZY ONIONS LIKE Gene in Regulating Cell Death and Defense in Arabidopsis.

Programmed cell death (PCD) is critical for development and responses to environmental stimuli in many organisms. FUZZY ONIONS (FZO) proteins in yeast, flies, and mammals are known to affect mitochondrial fusion and function. Arabidopsis FZO-LIKE (FZL) was shown as a chloroplast protein that regulates chloroplast morphology and cell death. We cloned the FZL gene based on the lesion mimic phenotype conferred by an fzl mutation. Here we provide evidence to support that FZL has evolved new function different from its homologs from other organisms. We found that fzl mutants showed enhanced disease resistance to the bacterial pathogen Pseudomonas syringae and the oomycete pathogen Hyaloperonospora arabidopsidis. Besides altered chloroplast morphology and cell death, fzl showed the activation of reactive oxygen species (ROS) and autophagy pathways. FZL and the defense signaling molecule salicylic acid form a negative feedback loop in defense and cell death control. FZL did not complement the yeast strain lacking the FZO1 gene. Together these data suggest that the Arabidopsis FZL gene is a negative regulator of cell death and disease resistance, possibly through regulating ROS and autophagy pathways in the chloroplast.

Multiple Domain Associations within the Arabidopsis Immune Receptor RPP1 Regulate the Activation of Programmed Cell Death.

Upon recognition of pathogen virulence effectors, plant nucleotide-binding leucine-rich repeat (NLR) proteins induce defense responses including localized host cell death. In an effort to understand the molecular mechanisms leading to this response, we examined the Arabidopsis thaliana NLR protein RECOGNITION OF PERONOSPORA PARASITICA1 (RPP1), which recognizes the Hyaloperonospora arabidopsidis effector ARABIDOPSIS THALIANA RECOGNIZED1 (ATR1). Expression of the N-terminus of RPP1, including the Toll/interleukin-1 receptor (TIR) domain ("N-TIR"), elicited an effector-independent cell death response, and we used allelic variation in TIR domain sequences to define the key residues that contribute to this phenotype. Further biochemical characterization indicated that cell death induction was correlated with N-TIR domain self-association. In addition, we demonstrated that the nucleotide-binding (NB)-ARC1 region of RPP1 self-associates and plays a critical role in cell death activation, likely by facilitating TIR:TIR interactions. Structural homology modeling of the NB subdomain allowed us to identify a putative oligomerization interface that was shown to influence NB-ARC1 self-association. Significantly, full-length RPP1 exhibited effector-dependent oligomerization and, although mutations at the NB-ARC1 oligomerization interface eliminated cell death induction, RPP1 self-association was unaffected, suggesting that additional regions contribute to oligomerization. Indeed, the leucine-rich repeat domain of RPP1 also self-associates, indicating that multiple interaction interfaces exist within activated RPP1 oligomers. Finally, we observed numerous intramolecular interactions that likely function to negatively regulate RPP1, and present a model describing the transition to an active NLR protein.

Mortality from Alzheimer's disease in Brazil, 2000-2009 / Enfermedad de Alzheimer: estudio de la mortalidad en Brasil, 2000-2009 / Doença de Alzheimer: estudo da mortalidade no Brasil, 2000-2009

Alzheimer's disease is the most prevalent type of dementia in the elderly worldwide. To evaluate the mortality trend from Alzheimer's disease in Brazil, a descriptive study was conducted with the Mortality Information System of the Brazilian Ministry of Health (2000-2009). Age and sex-standardized mortality rates were calculated in Brazil's state capitals, showing the percentage variation by exponential regression adjustment. The state capitals as a whole showed an annual growth in mortality rates in the 60 to 79 year age bracket of 8.4% in women and 7.7% in men. In the 80 and older age group, the increase was 15.5% in women and 14% in men. Meanwhile, the all-cause mortality rate declined in both elderly men and women. The increase in mortality from Alzheimer's disease occurred in the context of chronic diseases as a proxy for increasing prevalence of the disease in the population. The authors suggest healthcare strategies for individuals with chronic non-communicable diseases.

La enfermedad de Alzheimer es la demencia más frecuente entre adultos mayores en el mundo. Para evaluar la evolución de la mortalidad por la enfermedad de Alzheimer en Brasil, se ha desarrollado un estudio con datos del Sistema de Información sobre Mortalidad del Ministerio de Salud, durante el período 2000-2009. Se calcularon las tasas de mortalidad estandarizadas por edad y sexo en las capitales brasileñas y se registró la variación porcentual mediante ajuste de la regresión exponencial. El conjunto de las capitales presentó un aumento anual de las tasas de mortalidad en el grupo de edad de 60 a 79 años, de un 8,4% en mujeres y un 7,7% en hombres. En el grupo de 80 o más años, el aumento fue de un 15,5% en mujeres y un 14% en hombres. No obstante, hubo una disminución en la tasa de mortalidad por todas las causas entre los adultos mayores de ambos sexos. Se destaca un aumento de la mortalidad por enfermedad de Alzheimer en el contexto de las enfermedades crónicas como un proxy para la prevalencia de la enfermedad en la población, y se indican estrategias de asistencia en el cuidado de pacientes con enfermedades de larga duración.

A doença de Alzheimer é o tipo de demência que mais prevalece entre os idosos no mundo. Para avaliar a evolução da mortalidade por doença de Alzheimer no Brasil foi desenvolvido um estudo descritivo com os dados do Sistema de Informações sobre Mortalidade do Ministério da Saúde, no período de 2000 a 2009. Calcularam-se as taxas de mortalidade padronizadas por idade e sexo nas capitais brasileiras e se observou a variação percentual por meio de ajuste por regressão exponencial. Para o conjunto das capitais houve um crescimento anual nas taxas de mortalidade na faixa etária de 60 a 79 anos de 8,4% entre as mulheres e 7,7% entre os homens. No grupo etário de 80 anos e mais, o aumento foi de 15,5% entre as mulheres e 14% entre os homens. Contrariamente, verificou-se declínio da taxa de mortalidade por todas as causas entre os idosos em ambos os sexos. Destaca-se o aumento da mortalidade por doença de Alzheimer no contexto das doenças crônicas como um indicador aproximado da prevalência da doença na população, e são apontadas estratégias de assistência ao cuidado dos portadores de doenças de longa duração.

A downy mildew effector attenuates salicylic acid-triggered immunity in Arabidopsis by interacting with the host mediator complex.

Plants are continually exposed to pathogen attack but usually remain healthy because they can activate defences upon perception of microbes. However, pathogens have evolved to overcome plant immunity by delivering effectors into the plant cell to attenuate defence, resulting in disease. Recent studies suggest that some effectors may manipulate host transcription, but the specific mechanisms by which such effectors promote susceptibility remain unclear. We study the oomycete downy mildew pathogen of Arabidopsis, Hyaloperonospora arabidopsidis (Hpa), and show here that the nuclear-localized effector HaRxL44 interacts with Mediator subunit 19a (MED19a), resulting in the degradation of MED19a in a proteasome-dependent manner. The Mediator complex of ∼25 proteins is broadly conserved in eukaryotes and mediates the interaction between transcriptional regulators and RNA polymerase II. We found MED19a to be a positive regulator of immunity against Hpa. Expression profiling experiments reveal transcriptional changes resembling jasmonic acid/ethylene (JA/ET) signalling in the presence of HaRxL44, and also 3 d after infection with Hpa. Elevated JA/ET signalling is associated with a decrease in salicylic acid (SA)-triggered immunity (SATI) in Arabidopsis plants expressing HaRxL44 and in med19a loss-of-function mutants, whereas SATI is elevated in plants overexpressing MED19a. Using a PR1::GUS reporter, we discovered that Hpa suppresses PR1 expression specifically in cells containing haustoria, into which RxLR effectors are delivered, but not in nonhaustoriated adjacent cells, which show high PR1::GUS expression levels. Thus, HaRxL44 interferes with Mediator function by degrading MED19, shifting the balance of defence transcription from SA-responsive defence to JA/ET-signalling, and enhancing susceptibility to biotrophs by attenuating SA-dependent gene expression.

Inheritance of downy mildew (Plasmopara viticola) and anthracnose (Sphaceloma ampelinum) resistance in grapevines.

Downy mildew (Plasmopara viticola) and anthracnose (Sphaceloma ampelinum) are two of the major diseases of most grapevine (Vitis vinifera L.) cultivars grown in Thailand. Therefore, breeding grapevines for improved downy mildew and anthracnose resistance is crucial. Factorial crosses were made between three downy mildew and/or anthracnose resistant lines ('NY88.0517.01', 'NY65.0550.04', and 'NY65.0551.05'; male parents) and two or three susceptible cultivars of V. vinifera ('Black Queen', 'Carolina Black Rose', and/or 'Italia'; female parents). F1 hybrid seedlings were evaluated for downy mildew and anthracnose resistance using a detached/excised leaf assay. For both diseases, the general combining ability (GCA) variance among male parents was significant, while the variance of GCA among females and the specific combining ability (SCA) variance were not significant, indicating the prevalence of additive over non-additive gene actions. The estimated narrow sense heritabilities of downy mildew and anthracnose resistance were 55.6 and 79.2%, respectively, suggesting that downy mildew/anthracnose resistance gene(s) were highly heritable. The 'Carolina Black Rose x NY65.0550.04' cross combination is recommended for future use.

Mechanisms of nuclear suppression of host immunity by effectors from the Arabidopsis downy mildew pathogen Hyaloperonospora arabidopsidis (Hpa).

Filamentous phytopathogens form sophisticated intracellular feeding structures called haustoria in plant cells. Pathogen effectors are likely to play a role in the establishment and maintenance of haustoria additional to their more characterized role of suppressing plant defense. Recent studies suggest that effectors may manipulate host transcription or other nuclear regulatory components for the benefit of pathogen development. However, the specific mechanisms by which these effectors promote susceptibility remain unclear. Of two recent screenings, we identified 15 nuclear-localized Hpa effectors (HaRxLs) that interact directly or indirectly with host nuclear components. When stably expressed in planta, nuclear HaRxLs cause diverse developmental phenotypes highlighting that nuclear effectors might interfere with fundamental plant regulatory mechanisms. Here, we report recent advances in understanding how a pathogen can manipulate nuclear processes in order to cause disease.