Variation in ploidy level and morphological traits in the progeny of the triploid apple variety jonagold

Abstract

Variation with respect to both ploidy level and morphology was characterized for a set of 690 seedlings of the triploid apple variety Jonagold, of which 481 were obtained via in vitro culture of mature embryos, and 209 via conventional germination. Their ploidy level was determined by a combination of flow cytometry and root tip chromosome counting. The assessed morphological traits were leaf length, width and shape, stomatal density, guard cell length and chloroplast width and number. A total of 452 seedlings were aneuploid, 225 diploid, nine triploid and four tetraploid. All four tetraploid seedlings were derived by in vitro culture. When the triploid seedlings were genotyped at the S-locus and at selected microsatellite loci, we found that the Jonagold stigma was compatible with pollen which shared some of the maternal parent S-locus alleles.