Selfed embryo death in Pinus taeda: A phenotypic profile

Abstract

• Selective elimination of selfed embryos, or inbreeding depression, is shared among many members of the Pinaceae but it has not been fully characterized at the phenotypic level. • Here, two death pattern model hypotheses are tested using 10 621 Pinus taeda embryos sampled in two cohorts. Cones from a single pedigree based on selfed, outbred, parent-offspring and offspring-parent matings were destructively sampled weekly before, during and after fertilization. • Selfed embryo deaths adhered to two patterns over the course of development: death was linear with respect to days from fertilization; and a stage-specific death peak occurred during the early embryogeny stage. This death peak occurred from 23 to 36 d after fertilization in the 2004 cohort and from 27 to 34 d after fertilization in the 2006 cohort. Of those selfed embryos that died, 64-83% died at stages where a single dominant embryo was elongating inside the female gametophyte. • Additional genetic models are needed to account for the stage-specific death component of selfed P. taeda embryos. © The Author (2008).