RESUMO
Malic enzymes (ME) catalyze the decarboxylation of malate generating pyruvate, CO2 and NADH or NADPH. In some organisms it has been established that ME is involved in lipids biosynthesis supplying carbon skeletons and reducing power. In this work we studied the MEs of soybean and castor, metabolically different oilseeds. The comparison of enzymatic activities, transcript profiles and organic acid contents suggest different metabolic strategies operating in soybean embryo and castor endosperm in order to generate precursors for lipid biosynthesis. In castor, the malate accumulation pattern agrees with a central role of this metabolite in the provision of carbon to plastids, where the biosynthesis of fatty acids occurs. In this regard, the genome of castor possesses a single gene encoding a putative plastidic NADP-ME, whose expression level is high when lipid deposition is active. On the other hand, NAD-ME showed an important contribution to the maturation of soybean embryos, perhaps driving the carbon relocation from mitochondria to plastids to support the fatty acids synthesis in the last stages of seed filling. These findings provide new insights into intermediary metabolism in oilseeds and provide new biotechnological targets to improve oil yields.
Assuntos
Glycine max/enzimologia , Malato Desidrogenase/metabolismo , Proteínas de Plantas/metabolismo , Ricinus communis/enzimologia , Sementes/enzimologia , Carbono/metabolismo , Ricinus communis/crescimento & desenvolvimento , Metabolismo dos Lipídeos , Plastídeos/metabolismo , Sementes/crescimento & desenvolvimento , Glycine max/crescimento & desenvolvimentoRESUMO
Current demands for the genetic breeding of castor bean include the adaptation of genotypes to low altitudes to expand the potential areas of cultivation. This study was conducted to evaluate the response of different genotypes of castor bean that were sown in winter and summer at a low altitude. The study was conducted in northwestern Rio de Janeiro State at an altitude of 60 m. The treatments consisted of genotypes IAC 80, AL Guarany 2002, BRS 149 Nordestina, BRS 188 Paraguaçu, Savana, Lyra, Mirante 10, IAC 226, Cafelista, G1, V1, and T1 with spaces of 2.0 m between rows, 1.0 m between plants, and one plant per hole. The plant height, number and length of racemes, number of fruits per raceme, seed yield, and incidence of gray mold were determined. The highest yields in both seasons were obtained by the genotypes BRS 149 Nordestina, G1, BRS 188 Paraguaçu, and IAC 226. The genotypes Savannah and Lyra had the lowest yields in both cultivation seasons. The genotypes responded differently to the environmental conditions depending on the growing season, and the spring-summer period was found to be more favorable at the low altitude of the study site.
Assuntos
Altitude , Interação Gene-Ambiente , Ricinus communis/genética , Estações do Ano , Biomassa , Brasil , Ricinus communis/crescimento & desenvolvimento , Ecologia/métodos , Ecossistema , Genótipo , Geografia , Umidade , Chuva , TemperaturaRESUMO
We determined the length, volume, dry biomass, and density in seeds of five castor bean cultivars and verified notable physicochemical trait differences. Seeds were then subjected to different toxic aluminum (Al) concentrations to evaluate germination, relative root elongation, and the role of root apices' rhizosphere mucilage layer. Seeds' physicochemical traits were associated with Al toxicity responses, and the absence of Al in cotyledons near to the embryo was revealed by Al-hematoxylin staining, indicating that Al did not induce significant germination reduction rates between cultivars. However, in the more sensitive cultivar, Al was found around the embryo, contributing to subsequent growth inhibition. After this, to investigate the role of mucilage in Al tolerance, an assay was conducted using NH4Cl to remove root mucilage before or after exposure to different Al concentrations. Sequentially, the roots were stained with hematoxylin and a quantitative analysis of staining intensity was obtained. These results revealed the significant contribution of the mucilage layer to Al toxicity responses in castor bean seedlings. Root growth elongation under Al toxicity confirmed the role of the mucilage layer, which jointly indicated the differential Al tolerance between cultivars and an efficient Al-exclusion mechanism in the tolerant cultivar.
Assuntos
Alumínio/farmacologia , Mucilagem Vegetal/fisiologia , Ricinus communis/crescimento & desenvolvimento , Sementes/crescimento & desenvolvimento , Poluentes do Solo/farmacologia , Alumínio/metabolismo , Biocombustíveis , Ricinus communis/efeitos dos fármacos , Ricinus communis/metabolismo , Fenótipo , Raízes de Plantas/efeitos dos fármacos , Raízes de Plantas/crescimento & desenvolvimento , Raízes de Plantas/metabolismo , Rizoma/efeitos dos fármacos , Rizoma/crescimento & desenvolvimento , Rizoma/metabolismo , Plântula/efeitos dos fármacos , Plântula/crescimento & desenvolvimento , Plântula/metabolismo , Sementes/efeitos dos fármacos , Sementes/metabolismo , Poluentes do Solo/metabolismoRESUMO
Castor bean (Ricinus communis L.) is cultivated mainly for biodiesel production because of its oil-rich seeds; it is assumed to be an anemophylous species. But pollination deficit can lead to low productivity often attributed to other reasons. In this paper, we investigated pollination requirements, pollination mechanism, occurrence of pollination deficit, and the role of biotic pollinators in a large commercial plantation of castor bean. Our results show that R. communis bears a mixed breeding system favoring selfing by geitonogamy, although the wind promotes mostly outcrossing. We also found that the honey bee (Apis mellifera L.) foraging on castor bean can both transfer pollen from male to female flowers within the same raceme and boost the release of airborne pollen by male flowers. Both situations increase geitonogamy rates, raising significantly fruit set and seed yield. This is the first report of an animal foraging activity increasing seed yield in an anemophilous and geitonogamous crop and elucidates the role of biotic pollinators in castor bean reproduction.
Assuntos
Abelhas/fisiologia , Ecossistema , Polinização/fisiologia , Ricinus communis/crescimento & desenvolvimento , Agricultura , Animais , Feminino , MasculinoRESUMO
The arbuscular mycorrhizal fungi (AMF) are a key, integral component of the stability, sustainability and functioning of ecosystems. In this study, we characterised the AMF biodiversity in a native vegetation soil and in a soil cultivated with Jatropha curcas or Ricinus communis, in a tropical system in Guantanamo (Cuba), in order to verify if a change of land use to biofuel plant production had any effect on the AMF communities. We also asses whether some soil properties related with the soil fertility (total N, Organic C, microbial biomass C, aggregate stability percentage, pH and electrical conductivity) were changed with the cultivation of both crop species. The AM fungal small sub-unit (SSU) rRNA genes were subjected to PCR, cloning, sequencing and phylogenetic analyses. Twenty AM fungal sequence types were identified: 19 belong to the Glomeraceae and one to the Paraglomeraceae. Two AMF sequence types related to cultured AMF species (Glo G3 for Glomus sinuosum and Glo G6 for Glomus intraradices-G. fasciculatum-G. irregulare) did not occur in the soil cultivated with J. curcas and R. communis. The soil properties (total N, Organic C and microbial biomass C) were higher in the soil cultivated with the two plant species. The diversity of the AMF community decreased in the soil of both crops, with respect to the native vegetation soil, and varied significantly depending on the crop species planted. Thus, R. communis soil showed higher AMF diversity than J. curcas soil. In conclusion, R. communis could be more suitable for the long-term conservation and sustainable management of these tropical ecosytems.
Assuntos
Biodiversidade , Biocombustíveis , Jatropha/microbiologia , Micorrizas/genética , Ricinus communis/microbiologia , Microbiologia do Solo , Agricultura , Ricinus communis/crescimento & desenvolvimento , Cuba , Ecossistema , Condutividade Elétrica , Concentração de Íons de Hidrogênio , Jatropha/crescimento & desenvolvimento , Tipagem Molecular , Técnicas de Tipagem Micológica , Filogenia , Raízes de Plantas/crescimento & desenvolvimento , Raízes de Plantas/microbiologia , Subunidades Ribossômicas Menores de Eucariotos/genética , Solo/análise , Solo/química , Clima TropicalRESUMO
In this study, we performed a proteomic analysis of nucellus from two developmental stages of Ricinus communis seeds by a GeLC-MS/MS approach, using of a high resolution orbitrap mass spectrometer, which resulted in the identification of a total of 766 proteins that were grouped into 553 protein groups. The distribution of the identified proteins in stages III and IV into different Gene Ontology categories was similar, with a remarkable abundance of proteins associated with the protein synthesis machinery of cells, as well as several classes of proteins involved in protein degradation, particularly of peptidases associated with programmed cell death. Consistent with the role of the nucellus in mediating nutrient transfer from maternal tissues to the endosperm and embryo, a significant proportion of the identified proteins are related to amino acid metabolism, but none of the identified proteins are known to have a role as storage proteins. Moreover for the first time, ricin isoforms were identified in tissues other than seed endosperm. Results are discussed in the context of the spatial and temporal distribution of the identified proteins within the nucellar cell layers.
Assuntos
Proteínas de Plantas/metabolismo , Ricinus communis/crescimento & desenvolvimento , Sementes/crescimento & desenvolvimento , Apoptose/fisiologia , Ricinus communis/genética , Proteômica , Ricina/metabolismo , Sementes/químicaRESUMO
This study evaluated Cd and Pb accumulation by castor bean (Ricinus communis cv. Guarany) plants grown in nutrient solution, aiming to assess the plant's ability and tolerance to grow in Cd- and Pb-contaminated solutions for phytoremediation purposes. The plants were grown in individual pots containing Hoagland and Arnon's nutrient solution with increasing concentrations of Cd and Pb. The production of root and shoot dry matter and their contents of Cd, Pb, Ca, Mg, Cu, Fe, Mn, and Zn were evaluated in order to calculate the translocation and bioaccumulation factors, as well as toxicity of Cd and Pb. Cadmium caused severe symptoms of phytotoxicity in the plant's root and shoot, but no adverse effect was observed for Pb. Castor bean is an appropriate plant to be used as indicator plant for Cd and tolerante for Pb in contaminated solution and it can be potentially used for phytoremediation of contaminated areas.