RESUMO
For the purpose of understanding the molecular processes triggered during callus formation in macaw palm, the expression of seven genes potentially involved in this process, identified in previous studies and from the literature, was investigated by RT-qPCR. In addition, in situ hybridization of the SERK gene was performed. Leaf tissues from adult plants from two macaw palm accession were inoculated in a medium combined with Picloram at a concentration of 450 µM to induce callus. The expression analysis was performed from leaf samples from two accessions of different origins (Municipalities of Tiros, MG, and Buriti Vermelho, DF, Brazil), which are characterized as non-responsive (NR) and responsive (R), respectively. The material was collected before callus induction (0 DAI, initial day) and 120 days after callus induction (120 DAI). Genes related to development (SERK, OASA, EF1, ANN1) and stress (LEA, CAT2, and MDAR5) were evaluated. The results obtained showed that all the genes involved with the development had their expressions downregulated at 0 DAI when the accession R was compared with the accession NR. On the other hand, it was possible to observe that these genes were upregulated at 120 DAI. The LEA stress gene showed a tendency to increase expression in the NR accession, while the R accession showed decreased expression and the CAT2 and MDAR5 genes showed upregulation in both accessions. In situ hybridization showed SERK transcripts in the vascular bundles, indicating the expression of SERK in this region, in addition to its expression in calluses. The results obtained in this study support our hypothesis that the regulation of genes involved in the control of oxidative stress and development is crucial for the formation of calluses in macaw palm.
Assuntos
Arecaceae , Genes de Plantas , Arecaceae/genética , Hibridização In Situ , BrasilRESUMO
Butia odorata is a palm native to southern Brazil and Uruguay, not domesticated, much appreciated for its fruits and economic potential. However, the extractivism and the difficulty of propagation have led to the decline of natural populations. The objective of this work was to prove the possibility of induction of somatic embryogenesis in B. odorata. Mature zygotic embryos were induced in two media, MS and Y3, combined with auxin 2,4-D and picloram in five concentrations (2,4-D: 0, 361.99, 452.49, 542.99 and 633.48 µM/L, picloram: 0, 50, 150, 300 and 450 µM/L). The results promising during induction with the formation of embryogenic calli and somatic embryos, however the regeneration of them was not efficient, this may be due to the occurrence of somatic embryos fused during its development. The roots were formed, but the aerial part remained molten, not completing its development. Auxin picloram and Y3 medium provided the most adequate conditions for calogenesis, formation of embryogenic callus and somatic embryos, with concentrations of 150, 300 and 450 µM/L. This is the first description of somatic embryogenesis in B. odorata that will serve as the basis for future research and adjustments of the methodology proposed here.
Assuntos
Arecaceae , Brasil , Desenvolvimento Embrionário , Técnicas de Embriogênese Somática de Plantas , UruguaiRESUMO
Crop production may benefit from plant growth-promoting bacteria. The knowledge on bacterial communities is indispensable in agricultural systems that intend to apply beneficial bacteria to improve plant health and production of crops such as canola. In this work, the diversity of root bacterial communities associated to two different developmental phases of canola (Brassica napus L.) plants was assessed through the application of new generation sequencing technology. Total bacterial DNA was extracted from root samples from two different growth states of canola (rosette and flowering). It could be shown how bacterial communities inside the roots changed with the growing stage of the canola plants. There were differences in the abundance of the genera, family, and even the phyla identified for each sample. While in both root samples Proteobacteria was the most common phylum, at the rosette stage, the most common bacteria belonged to the family Pseudomonadaceae and the genus Pseudomonas, and in the flowering stage, the Xanthomonadaceae family and the genus Xanthomonas dominated the community. This implies in a switch in the predominant bacteria in the different developmental stages of the plant, suggesting that the plant itself interferes with the associated microbial community.
Assuntos
Bactérias/isolamento & purificação , Brassica napus/crescimento & desenvolvimento , Raízes de Plantas/microbiologia , Microbiologia do Solo , Bactérias/classificação , Bactérias/genética , Técnicas de Tipagem Bacteriana , Biodiversidade , Brassica napus/microbiologia , Sequenciamento de Nucleotídeos em Larga Escala , Dados de Sequência Molecular , Filogenia , Raízes de Plantas/crescimento & desenvolvimentoRESUMO
Paenibacillus riograndensis SBR5(T), a nitrogen-fixing Gram-positive rhizobacterium isolated from a wheat field in the south of Brazil, has a great potential for agricultural applications due to its plant growth promotion effects. Here we present the draft genome sequence of P. riograndensis SBR5(T). Its 7.37-Mb genome encodes determinants of the diazotrophic lifestyle and plant growth promotion, such as nitrogen fixation, antibiotic resistance, nitrate utilization, and iron uptake.
Assuntos
Genoma Bacteriano , Fixação de Nitrogênio , Paenibacillus/genética , Triticum/microbiologia , Sequência de Bases , Dados de Sequência Molecular , Paenibacillus/isolamento & purificação , Paenibacillus/metabolismo , Triticum/crescimento & desenvolvimentoRESUMO
Bradyrhizobium elkanii SEMIA587 is a symbiotic nitrogen-fixing bacterium of the group commonly called rhizobia, which induce nodule formation in legumes, and is widely used in Brazilian commercial inoculants of soybean. In response to flavonoid compounds released by plant roots, besides Nod factors, other molecular signals are secreted by rhizobia, such as proteins secreted by type III secretion systems (T3SSs). Rhizobial T3SSs are activated by the transcription regulator TtsI, which binds to sequences present in the promoter regions of T3SS genes via a conserved sequence called the tts box. To study the role of the T3SS of B. elkanii SEMIA587, ttsI was mutated. Protein secretion and flavonoid induction analysis, as well as nodulation tests, were performed with the wild-type and mutant strains. The results obtained showed that B. elkanii SEMIA587 secretes at least two proteins (NopA and NopL, known rhizobial T3SS substrates) after genistein induction, whilst supernatants of the ttsI mutant did not contain these Nops. Unusually for rhizobia, the promoter region of the B. elkanii SEMIA587 ttsI gene contains a tts box, which is responsive to flavonoid induction and to which TtsI can bind. Nodulation tests performed with three different leguminous plants showed that the B. elkanii SEMIA587 ttsI mutant displays host-dependent characteristics; in particular, nodulation of two soybean cultivars, Peking and EMBRAPA 48, was more efficient when TtsI of B. elkanii was functional.
Assuntos
Proteínas de Bactérias/metabolismo , Sistemas de Secreção Bacterianos , Bradyrhizobium/efeitos dos fármacos , Flavonoides/farmacologia , Regulação Bacteriana da Expressão Gênica , Glycine max/microbiologia , Fatores de Transcrição/metabolismo , Proteínas de Bactérias/química , Proteínas de Bactérias/genética , Sequência de Bases , Bradyrhizobium/genética , Bradyrhizobium/crescimento & desenvolvimento , Bradyrhizobium/metabolismo , Sequência Conservada , Elementos Facilitadores Genéticos , Flavonoides/metabolismo , Genisteína/metabolismo , Genisteína/farmacologia , Isoflavonas/metabolismo , Isoflavonas/farmacologia , Dados de Sequência Molecular , Mutação , Regiões Promotoras Genéticas , Análise de Sequência de DNA , Glycine max/metabolismo , Simbiose , Fatores de Transcrição/química , Fatores de Transcrição/genéticaRESUMO
In this work, we further analyzed an Azospirillum brasilense Sp7 mutant (Sp7::Tn5-33) showing a pleiotrophic phenotype due to a Tn5 insertion into an open reading frame of 840 bp (orf280). The deduced amino acid sequence of this region has high similarity to a family of universal stress proteins. Because the most interesting property exhibited by the Sp7::Tn5-33 mutant was an enhanced in vitro nitrogen fixation activity, we addressed the question of whether it could benefit the host plant. We found that the increased nitrogenase activity at the free-living state of the mutant bacterium was correlated with an increased production of the nitrogenase reductase protein (NifH), in amounts approximately 1.5 times higher than the wild type. The mutant strain exhibited the same level of auxin production and the same colonization pattern of wheat roots as the wild type. We also observed that Sp7::Tn5-33 increased the total plant dry weight, although the N content did not differ significantly between wheat plants inoculated with mutant or wild-type strains.