Seca em eucalipto: identificação de módulos genéticos associados a características fisiológicas, análise genômica do RNA longo não codante e família do fator de transcrição AREB/ABF

Abstract

Drought is among the worst stresses for agriculture and with the advance of global warming an increase in damage to production is expected. Rapidly growing species, such as eucalyptus, tend to suffer more from lack of water. Eucalyptus is the most planted woody species in Brazil, due to its rapid growth and easy crossing. The generation of hybrids can provide a variability of the species that respond differently to stresses. This makes it possible to identify contrasting species and makes it possible to identify metabolic pathways that help with stress tolerance. Since drought tolerance is a multigenic characteristic, this work aimed to identify gene modules associated with physiological characteristics related to drought in contrasting eucalyptus clones (VM01 and VM05) submitted to different levels of drought. RNA-seq from the two clones in response to drought were analyzed using NOISeq, 2504 differentially expressed genes were grouped into 10 modules and associated with 18 physiological traits. Several modules showed an association with known physiological responses to drought. The modules' genes, most correlated with physiological traits, were grouped in patterns using Fuzzy k-means. Among the nine patterns, two stood out for presenting increased and decreased expression with the advance of drought. As abscisic acid (ABA) was one of the characteristics that differentiated the tolerant clone from the sensitive one, this work aimed to characterize the ABA-responsive element (ABRE/AREB) binding factors (ABFs) genetic family. Fifteen members were identified in the Eucalyptus grandis genome. Specific tissue studies have shown that this family of transcription factors is expressed more in the root than in the leaf. The differentially expressed genes of the AREB/ABF family showed a co-expression network isolated in the root and highly shared in the leaf. In addition to transcription factors, long non-coding RNAs (lncRNA) play an important regulatory role in response to stresses. In this way, 1468 lncRNA in Eucalyptus were characterized with high reliability. LncRNAs have been shown to be both tissue specific and species specific. In Eucalyptus globulus, eight lncRNA were differentially expressed in response to drought and indicated participating in the regulation of several genes related to responses to drought. Therefore, this work contributed with several new information regarding water stress in eucalyptus, mainly related to its regulatory process. The published articles may serve as a source for further studies and assist in the genetic improvement of eucalyptus in response to drought.