FuturaGene, Suzano’s biotechnology subsidiary, in partnership with the company’s genetic improvement team, identified molecular markers associated with eucalyptus tolerance to Eucalyptus Physiological Disorder (DFE).
This disorder is an important abiotic disease that significantly reduces the productivity of eucalyptus plantations, being reported for the first time in 2005, in the coastal regions of the Brazilian states of Espírito Santo and Bahia – areas that until then were considered highly productive for clonal eucalyptus plantations.
Clones susceptible to the disease began to show loss of apical dominance, with death of branches and leaves, evolving to cankers and epicormic sprouts along the trunk. This type of clone came to express symptoms homogeneously and depending on the location and susceptibility of the genetic material, it can collapse and die.
The origin of this important abiotic disease remains unknown, but it has strong genetic control. Thus, the selection of genetic materials resistant to DFE is the only alternative to avoid damage to plantations.
Before the development of molecular markers, the selection of resistant clones was based on the results of long evaluations carried out in an extensive network of field experiments. These assessments require the planting of clonal tests in various regions and the monitoring of these experiments for a period of one to two planting cycles, that means from 7 to 14 years, resulting in a very expensive and time-consuming process.
For this reason, the discovery of FuturaGene allows an early selection of clones resistant to the disorder. In 2012, researchers from the company installed a series of experiments in regions considered hot spots for DFE and analyzed the segregation rate between the number of resistant individuals and the number of susceptible ones.
Based on the results of these analyses, the researchers identified the opportunity to look for markers in the eucalyptus genome that could be used for early selection of DFE-resistant clones.
Approximately 10 thousand genetic materials, including clones and individual progenies, were characterized in the field, related to resistance or susceptibility to DFE. Approximately 2,500 individuals had their genomes completely sequenced; another 500 individuals were genotyped using the Illumina 60K SNP-Chip. The data generated were analyzed, in parallel, by the bioinformatics team at FuturaGene and by partner companies of Suzano in Brazil (Agropartners), Israel (NRGENE) and the United States (RapidGenomics).
As a result, genomic regions strongly associated with DFE resistance were identified, enabling the development of molecular markers to be used in the early selection of resistant clones still in the molting phase, before being taken to the field, with an anticipated phenotype precision greater than 90 %.
These molecular markers are currently being used in Suzano’s improvement program in the Brazilian states of Bahia and Espírito Santo, enabling the selection of DFE-resistant clones. This is the first time that molecular markers have been used on an operational scale in the forestry sector, a pioneering work carried out by the Suzano team, which opens opportunities for further studies in the area of assisted selection.