No evidence of apomixis in matroclinal progeny from experimental crosses in the genus Fragaria (strawberry) based on RAPDs

Crossing experiments in Fragaria have frequently resulted in some matroclinal progeny. These have been attributed to either accidental selfing and/or pollen contamination, or apomixis. In this study 202 carefully controlled intra and interspecific crosses in Fragaria were made. No progeny were produced from 164 interploid crosses made between diploids, hexaploids and octoploids but 38 intraploid crosses resulted in 904 F-1 plants, of which 42 (4.6%) were found to be morphologically matroclinal. All matroclinal progeny subsequently studied by RAPDs were found to be hybrids and not apomicts. The absence of apomixis among matroclinal progeny in this study casts doubt on previous reports of apomixis in Fragaria. Our results showed that the complete morphological similarity of progeny to the seed parent, even in recessive characteristics, cannot therefore be taken as evidence of apomixis, and may rather indicate the heterozygosity of the pollen parent, emphasising the need to use DNA markers for confirmation of apomixis.