Biomarkers for early selection in eucalyptus tolerant to dieback associated with water deficit

Water deficit causes a number of changes in plant development and physiology and is reported to be a trigger for eucalyptus dieback disorder. Dieback manifests itself in adult individuals, which hampers the selection of tolerant material and, therefore, means potential jeopardy to commercial plantings. Genetic parameters of phenotypic traits were estimated by the mixed model methodology (REML/BLUP), based on the observation of seedlings from twelve commercial eucalyptus clones grown under water stress. The water deficit was simulated by using polyethylene glycol (PEG 6000) and controlling the water depth administered to the plants for a period of 120 days. Among the evaluated anatomical and physiological characteristics, 10 biomarkers were selected for discriminating the clones, based on their differentiated and significant response among genotypes as well as relevant heritability and accuracy. The best-ranked clones demonstrated tolerance pattern in accordance to the empirical information in the production fields. Our results support the feasibility of early selection for selecting eucalyptus genotypes more tolerant to dieback and to water deficit.