AtAREB1 overexpression in cotton enhances water use efficiency but not improve growth in response to mild drought.

Plants have evolved complex mechanisms to cope efficiently with drought. Abscisic acid (ABA)-responsive element binding (AREB) proteins are a family of ABA-dependent transcription factors that control the expression of stress-induced genes to improve drought tolerance. It has been hypothesized that overexpression of AREB1 constitutively active is able to increase plantwater deficit resistance

AtAREB1 overexpression in cotton enhances water use efficiency but not improve growth in response to mild drought.

Plants have evolved complex mechanisms to cope efficiently with drought. Abscisic acid (ABA)-responsive element binding (AREB) proteins are a family of ABA-dependent transcription factors that control the expression of stress-induced genes to improve drought tolerance. It has been hypothesized that overexpression of AREB1 constitutively active is able to increase plantwater deficit resistance

Implications of ethylene biosynthesis and signaling in soybean drought stress tolerance

Abstract\ud \ud Background\ud Ethylene is a phytohormone known for inducing a triple response in seedlings, leaf abscission and other responses to various stresses. Several studies in model plants have evaluated the importance of this hormone in crosstalk signaling with different metabolic pathways, in addition to responses to biotic stresses. However, the mechanism of action in plants of agricultural interest, such as soybean, and its participation in abiotic stresses remain unclear.\ud \ud \ud Results\ud The studies presented in this work allowed for the identification of 176 soybean genes described elsewhere for ethylene biosynthesis (108 genes) and signal transduction (68 genes). A model to predict these routes in soybean was proposed, and it had great representability compared to those described for Arabidopsis thaliana and Oryza sativa. Furthermore, analysis of putative gene promoters from soybean gene orthologs permitted the identification of 29 families of cis-acting elements. These elements are essential for ethylene-mediated regulation and its possible crosstalk with other signaling pathways mediated by other plant hormones.\ud From genes that are differentially expressed in the transcriptome database, we analyzed the relative expression of some selected genes in resistant and tolerant soybean plants subjected to water deficit. The differential expression of a set of five soybean ethylene-related genes (MAT, ACS, ACO, ETR and CTR) was validated with RT-qPCR experiments, which confirmed variations in the expression of these soybean target genes, as identified in the transcriptome database. In particular, two families of ethylene biosynthesis genes (ACS and ACO) were upregulated under these experimental conditions, whereas CTR (involved in ethylene signal transduction) was downregulated. In the same samples, high levels of ethylene production were detected and were directly correlated with the free fraction levels of ethylene’s precursor. Thus, the combination of these data indicated the involvement of ethylene biosynthesis and signaling in soybean responses to water stress.\ud \ud \ud Conclusions\ud The in silico analysis, combined with the quantification of ethylene production (and its precursor) and RT-qPCR experiments, allowed for a better understanding of the importance of ethylene at a molecular level in this crop as well as its role in the response to abiotic stresses. In summary, all of the data presented here suggested that soybean responses to water stress could be regulated by a crosstalk network among different signaling pathways, which might involve various phytohormones, such as auxins, ABA and jasmonic acid. The integration of in silico and physiological data could also contribute to the application of biotechnological strategies to the development of improved cultivars with regard to different stresses, such as the isolation of stress-specific plant promoters.This research was financially supported by grants from the Brazil Higher\ud Education Personnel Training Coordination (CAPES), the Brazil National\ud Council for Scientific and Technological Development (CNPq), the Brazilian\ud Foundation for Research Support (FAP-DF) and Embrapa Genetic Resources\ud and Biotechnology (Brazil)

Transgenic cotton expressing Cry10Aa toxin confers high resistance to the cotton boll weevil.

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Proteomic insights of Cowpea response to combined biotic and abiotic stresses.

Na publicação: Maria Fatima Grossi-de-Sá; Angela Mehta

In planta RNAi targeting Meloidogyne incognita Minc16803 gene perturbs nematode parasitism and reduces plant susceptibility.

Meloidogyne incognita is one of the most important plant-parasitic nematodes (PPNs) causing severe crop losses worldwide. Plants have evolved complex defense mechanisms to respond to PPNs attacks. Conversely, PPNs have evolved infection mechanisms that involve the secretion of effector proteins into host plants to suppress immune responses and facilitate para- sitism. Therefore, effector genes are attractive targets for the genetic improvement of plant resistance to M. incognita. In this study, we functionally characterized the Minc16803 (Minc3s00746g16803) putative effector gene to evaluate its role during plant-nematode interactions. First, we found that the Minc16803 gene is expressed in all nematode life stages and encodes a protein with an N-terminal signal peptide for secretion, a motif characteristic of effector proteins and with the absence of transmembrane domain. In addition, our data demonstrated that transgenic Arabidopsis thaliana lines overexpressing a Minc16803-dsRNA efficiently downregulated the Minc16803 transcripts in infecting nematodes. Furthermore, transgenic lines were significantly less susceptible to M. incognita compared to wild-type control plants. The number of galls per plant was reduced by up to 84%, while the number of egg masses per plant decreased by up to 93.3%. Moreover, galls and feed- ing sites in the roots of transgenic lines were smaller than those in the control plants. Histological analysis revealed giant cells without cytoplasm, disordered neighboring cells, and malformed maturing nematodes in transgenic galls. Curiously, numerous hatching ppJ2 juveniles were often observed near the female body within the transgenic root tissues before egg mass extrusion. All findings strongly suggest that Minc16803 gene is a promising target to engineer agricultural crops for M. incognita resistance through host-induced gene silencing.On-line first. Na publicação: Isabela Tristan Lourenço-Tessutti; Maria C. M. Silva; Leonardo L. P. Macedo; Maria Fatima Grossi-de-Sa

Integrated omic approaches reveal molecular mechanisms of tolerance during soybean and meloidogyne incognita interactions.

The root-knot nematode (RKN), Meloidogyne incognita, is a devastating soybean pathogen worldwide. The use of resistant cultivars is the most effective method to prevent economic losses caused by RKNs. To elucidate the mechanisms involved in resistance to RKN, we determined the proteome and transcriptome profiles from roots of susceptible (BRS133) and highly tolerant (PI595099) Glycine max genotypes 4, 12, and 30 days after RKN infestation. After in silico analysis, we described major defense molecules and mechanisms considered constitutive responses to nematodeinfestation, such as mTOR, PI3K-Akt, relaxin, and thermogenesis. The integrated data allowed us to identify protein families and metabolic pathways exclusively regulated in tolerant soybean genotypes. Among them, we highlighted the phenylpropanoid pathway as an early, robust, and systemic defense process capable of controlling M. incognita reproduction. Associated with this metabolic pathway, 29 differentially expressed genes encoding 11 different enzymes were identified, mainly from the flavonoid and derivative pathways. Based on differential expression in transcriptomic and proteomic data, as well as in the expression profile by RT?qPCR, and previous studies, we selected and overexpressed the GmPR10 gene in transgenic tobacco to assess its protective effect against M. incognita. Transgenic plants of the T2 generation showed up to 58% reduction in the M. incognita reproduction factor. Finally, data suggest that GmPR10 overexpression can be effective against the plant parasitic nematodeM. incognita, but its mechanism of action remains unclear. These findings will help develop new engineered soybean genotypes with higher performance in response to RKN infections

A mega urban project and two competing accumulation strategies: negotiating discourses of the Songdo International Business District development

For the understanding of the accumulation strategy behind a mega urban development project, the distinction should be made between the two different strategies of capital accumulation, which we term the rentextraction strategy (RES) and the socio-economic transformation of space strategy (STSS). This distinction is important because each is preferred by actors at different scales, thereby creating conflicts between them. Local actors are likely to prefer RES because its benefits mainly fall in the local area. National actors often prefer STSS because it symbolises state-level commitment to a business-friendly economic environment. Negotiation between these two strategies constitutes a major part of the formation of accumulation strategy. We test this theoretical prediction against the case of Songdo International Business District in South Korea. We find that the history of the project is consistent with our theoretical prediction

A Chemosensory GPCR as a Potential Target to Control the Root-Knot Nematode Meloidogyne incognita Parasitism in Plants

International audienceRoot-knot nematodes (RKN), from the Meloidogyne genus, have a worldwide distribution and cause severe economic damage to many life-sustaining crops. Because of their lack of specificity and danger to the environment, most chemical nematicides have been banned from use. Thus, there is a great need for new and safe compounds to control RKN. Such research involves identifying beforehand the nematode proteins essential to the invasion. Since G protein-coupled receptors GPCRs are the target of a large number of drugs, we have focused our research on the identification of putative nematode GPCRs such as those capable of controlling the movement of the parasite towards (or within) its host. A datamining procedure applied to the genome of Meloidogyne incognita allowed us to identify a GPCR, belonging to the neuropeptide GPCR family that can serve as a target to carry out a virtual screening campaign. We reconstructed a 3D model of this receptor by homology modeling and validated it through extensive molecular dynamics simulations. This model was used for large scale molecular dockings which produced a filtered limited set of putative antagonists for this GPCR. Preliminary experiments using these selected molecules allowed the identification of an active compound, namely C260-2124, from the ChemDiv provider, which can serve as a starting point for further investigations