RNA-Seq indica que Polietilenoglicol induz estresse de hipóxia nas raízes de Eucalyptus em hidroponia

• Autor(a) principal: Fagundes, Lucas França
• Data de Publicação: 2017
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: Repositório Institucional da UFG
• dARK ID: ark:/38995/001300000dshf
• Texto Completo: http://repositorio.bc.ufg.br/tede/handle/tede/8948
• topic: Hidroponia; Raíz; RNA-Seq; Eucalyptus; Hipóxia; Hydropony; Root; Eucalyptus; Hypoxia; CIENCIAS AGRARIAS::AGRONOMIA

Due in most part to the rapid growth and adaptability of the Eucalyptus in Brazil, the country's forestry sector is one of the most competitive of the world. Drought is one of the main obstacles of the culture, which has been expanding to the country’s interior regions such as the Cerrado biome. The objective of this work was to identify genes and biological processes involved in the responses of the Eucalyptus roots to drought. The experiment was conducted in a completely randomized design with 2 treatments (control and deficit) x 3 root RNA gathering time (3, 6 and 12h after start of treatment) and three biological replicates (commercial clones 1528, I144, VM1). The plants grew in hydroponics for 50 days, before the experiment start by using PEG8000 to induce water deficit (osmotic potential of -0.9 MPa). The root RNA of the seedlings was extracted using the RNeasy Plant Mini® kit (Quiagen). RNA samples were sequenced on the HiSeq 2000 platform (Illumina), yielding approximately 626 million 50 bp sequences in single end mode. After quality control, the sequences were aligned in the reference genome of Eucalyptus grandis. After counting reads aligned on each gene, differential expression analyses were performed with edgeR package of R/Bioconductor. A total of 6169 differentially expressed genes (DEG) (FDR ≤ 5% and Log2 FoldChange > |2|) were identified. Of these, 3350 were up-regulated and 2819 were repressed under osmotic stress, considering all the time-series evaluations. At three hours after treatment the highest number of DEG was obtained, with 3150, followed by six hours (2494 DEG) and 12h (525 DEG). Functional enrichment analysis was performed with the Fisher exact test, by software Blast2GO, with the DEG associated with their respective Gene Ontology (GO) terms. As a total of 90 GO terms, enriched and non-redundant, was verified that our results indicate a rapid initial response of Eucalyptus roots induced by PEG 8000 in hydroponics. The most remarkable characteristics of this response under hydroponic conditions are: increased energy consumption via carbohydrate catabolism, activation of the glycolytic pathway, repression of the respiratory chain in the mitochondria, increase of the fermentation pathway, partial execution of the citric acid cycle and repression of the primary metabolism (DNA replication and RNA biosynthesis, development and growth). These enriched functional terms point to the predominance of hypoxia stress, induced by the high viscosity of PEG in hydroponics, as compared to the osmotic stress.