Abstract
The present work aimed to characterize and identify QTLs for wood quality and growth traits in E. grandis x E. urophylla hybrids. For this purpose a RAPD linkage map was developed for the hybrids (LOD=3 and r=0.40) containing 52 markers and 12 linkage groups. Traits related to wood quality and growth were evaluated in the QTL analyses. QTL analyses were performed using chi-square tests, single-marker, interval mapping and composite interval mapping analyses. All approaches led to the identification of similar QTLs associated with wood density, cellulose pulp yield and percentage of extractives, which were detected and confirmed by both the interval mapping and composite interval mapping methodologies. Some QTLs regions were confirmed only by the composite interval mapping methodology: percentage of soluble lignin, percentage of insoluble lignin, CBH and total height. Overlapping QTLs regions were detected, and these, can be the result of major genes involved in the regulation and control of the growth traits by epistatic interactions. In order to evaluate the effect of early selection using RAPD molecular data, molecular markers adjacent to QTLs were used genotype selection. The analysis of selection differential values suggests that for all the traits the phenotypic selection at seven years should generate larger genetic gains than early selection assisted by molecular markers and the combination of the strategies should elevate the selection efficiency.
Highlights
At present, the most used species for reforestation projects in Brazil belong to the genus Eucalyptus (Myrtaceae) that stands out for the fast growth, easy management and good technological characteristics (TURNBULL, 1999)
Studies on wood technological characteristics are usually limited by the evaluation process, which can only be accomplished in adult plants and in laboratories with a good infrastructure
The growth traits circumference at breast height (CBH), total height, and commercial height were measured in 90 standing trees that had their leaves collected for DNA amplification
Summary
The most used species for reforestation projects in Brazil belong to the genus Eucalyptus (Myrtaceae) that stands out for the fast growth, easy management and good technological characteristics (TURNBULL, 1999). The growing interest for Eucalyptus wood can be sensed on the increase of the cultivated area with more than three million hectares between 1985 and 1994 and on the number of breeding programs aiming to obtain better raw material. To assist the high demand for quality raw material for paper and cellulose production, technological characteristics of the wood are nowadays a priority in forest improvement programs (CAMPINHOS, 1999). Studies on wood technological characteristics are usually limited by the evaluation process, which can only be accomplished in adult plants and in laboratories with a good infrastructure. Analysis automation has been a decisive factor for genetic studies of wood quality considering the high number of individuals that should be evaluated
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
