Genetics of physical wood properties and early growth in a tropical pine hybrid

Quantitative trait locus (QTL) detection was carried out for physical wood properties and early growth traits in an interspecific hybrid between Pinus elliottii var. elliottii Engelm. and Pinus caribaea var. hondurensis (Sénécl) Barr. et Golf. A pseudo-testcross QTL detection strategy was used to identify genome regions that influenced wood density, secondary growth, and dry wood mass index on each genetic map for the parents of a single F1 family (n = 133). Traits were measured for annual ring and earlywood and latewood components and were based on both individual and average ring values from 1996 to 1999. A total of 12 significant putative QTLs were identified that clustered into four genomic regions in the P. elliottii var. elliottii parent and a single region in the P. caribaea var. hondurensis parent. The P. elliottii var. elliottii parent largely contributed putative QTLs for diameter growth and wood density, whereas the P. caribaea var. hondurensis parent contributed a putative QTL for earlywood formed in 1997. Putative QTLs that influenced density and ring width did not colocate, suggesting independent inheritance of these characters. This was consistent with the lack of genetic correlation between wood density and diameter growth observed in quantitative studies in hybrid pines.