The Re-Establishment of Desiccation Tolerance in Germinated Arabidopsis thaliana Seeds and Its Associated Transcriptome

The combination of robust physiological models with “omics” studies holds promise for the discovery of genes and pathways linked to how organisms deal with drying. Here we used a transcriptomics approach in combination with an in vivo physiological model of re-establishment of desiccation tolerance (DT) in Arabidopsis thaliana seeds. We show that the incubation of desiccation sensitive (DS) germinated Arabidopsis seeds in a polyethylene glycol (PEG) solution re-induces the mechanisms necessary for expression of DT. Based on a SNP-tile array gene expression profile, our data indicates that the re-establishment of DT, in this system, is related to a programmed reversion from a metabolic active to a quiescent state similar to prior to germination. Our findings show that transcripts of germinated seeds after the PEG-treatment are dominated by those encoding LEA, seed storage and dormancy related proteins. On the other hand, a massive repression of genes belonging to many other classes such as photosynthesis, cell wall modification and energy metabolism occurs in parallel. Furthermore, comparison with a similar system for Medicago truncatula reveals a significant overlap between the two transcriptomes. Such overlap may highlight core mechanisms and key regulators of the trait DT. Taking into account the availability of the many genetic and molecular resources for Arabidopsis, the described system may prove useful for unraveling DT in higher plants

Dual-Level Regulation of ACC Synthase Activity by MPK3/MPK6 Cascade and Its Downstream WRKY Transcription Factor during Ethylene Induction in Arabidopsis

Plants under pathogen attack produce high levels of ethylene, which plays important roles in plant immunity. Previously, we reported the involvement of ACS2 and ACS6, two Type I ACS isoforms, in Botrytis cinerea–induced ethylene biosynthesis and their regulation at the protein stability level by MPK3 and MPK6, two Arabidopsis pathogen-responsive mitogen-activated protein kinases (MAPKs). The residual ethylene induction in the acs2/acs6 double mutant suggests the involvement of additional ACS isoforms. It is also known that a subset of ACS genes, including ACS6, is transcriptionally induced in plants under stress or pathogen attack. However, the importance of ACS gene activation and the regulatory mechanism(s) are not clear. In this report, we demonstrate using genetic analysis that ACS7 and ACS11, two Type III ACS isoforms, and ACS8, a Type II ACS isoform, also contribute to the B. cinerea–induced ethylene production. In addition to post-translational regulation, transcriptional activation of the ACS genes also plays a critical role in sustaining high levels of ethylene induction. Interestingly, MPK3 and MPK6 not only control the stability of ACS2 and ACS6 proteins via direct protein phosphorylation but also regulate the expression of ACS2 and ACS6 genes. WRKY33, another MPK3/MPK6 substrate, is involved in the MPK3/MPK6-induced ACS2/ACS6 gene expression based on genetic analyses. Furthermore, chromatin-immunoprecipitation assay reveals the direct binding of WRKY33 to the W-boxes in the promoters of ACS2 and ACS6 genes in vivo, suggesting that WRKY33 is directly involved in the activation of ACS2 and ACS6 expression downstream of MPK3/MPK6 cascade in response to pathogen invasion. Regulation of ACS activity by MPK3/MPK6 at both transcriptional and protein stability levels plays a key role in determining the kinetics and magnitude of ethylene induction

Digital Gene Expression Analysis Based on Integrated De Novo Transcriptome Assembly of Sweet Potato [Ipomoea batatas (L.) Lam.]

Background: Sweet potato (Ipomoea batatas L. [Lam.]) ranks among the top six most important food crops in the world. It is widely grown throughout the world with high and stable yield, strong adaptability, rich nutrient content, and multiple uses. However, little is known about the molecular biology of this important non-model organism due to lack of genomic resources. Hence, studies based on high-throughput sequencing technologies are needed to get a comprehensive and integrated genomic resource and better understanding of gene expression patterns in different tissues and at various developmental stages. Methodology/Principal Findings: Illumina paired-end (PE) RNA-Sequencing was performed, and generated 48.7 million of 75 bp PE reads. These reads were de novo assembled into 128,052 transcripts ($100 bp), which correspond to 41.1 million base pairs, by using a combined assembly strategy. Transcripts were annotated by Blast2GO and 51,763 transcripts got BLASTX hits, in which 39,677 transcripts have GO terms and 14,117 have ECs that are associated with 147 KEGG pathways. Furthermore, transcriptome differences of seven tissues were analyzed by using Illumina digital gene expression (DGE) tag profiling and numerous differentially and specifically expressed transcripts were identified. Moreover, the expression characteristics of genes involved in viral genomes, starch metabolism and potential stress tolerance and insect resistance were also identified

A participação e a criatividade como ferramentas de análise das políticas públicas

No contexto da globalização atual, importantes modificações das relações internacionais e dos componentes ideológicos, técnicos e culturais na administração dos Estados se expressam na falta de legitimidade de princípios da ação pública com consequente emergência do problema da iniquidade social e o debilitamento do papel do Estado. Os planos e programas de desenvolvimento, independente de sua origem política ou orientação ideológica, apresentam uma uniformidade imperante e o desafio atual implica a mobilização de competências locais, tendo como objetivo a mudança na qualidade da ação pública, mediante novas estratégias de desenvolvimento que integrem as novas dimensões sociais e outros dispositivos de ação. Um destes, a ação intersetorial, demanda uma revisão estrutural da fronteira administrativa e cultural dos agentes sociais, públicos e privados, como ensaio de um novo conserto sociopolítico. Toma como marco metodológico a complexidade das políticas, projetos e programas e os referenciais teóricos e metodológicos: integralidade, redes sociais e a sociopráxis, construindo um processo participativo de conhecimento para uma análise de políticas na busca de uma mudança na abordagem dos processos sociopolíticos a partir das redes locais, através de uma investigação de segunda ordem.In the context of current globalization, important modifications of the international relations and of the ideological, technical, and cultural components in the administration of the States are expressed by non-legitimate public action principles which account for social iniquity and the weakening of the role of the State. Regardless of its political origin or ideological orientation, the economic development plans and programs exhibit a prevailing uniformity. The challenge today implies mobilizing in local capacities with the objective of changing the quality of public action through the adoption of new development strategies able to integrate new social dimensions with other mechanisms of action. One of them, the intersectoral action, demands the structural revision of the administrative and cultural frontiers of the public and private social agents as a means of making a new tentative sociopolitical arrangement. The complexity of politics, projects and programs is taken as a methodological landmark based on the following theoretical presuppositions: integrality, social networks, and sociopraxis, constructing a participative process of knowledge to a political analysis in search of a change in the approach of the sociopolitical processes, starting from local social networks