Segregation distortion at isozyme locus Lap-1 in Schlumbergera (Cactaceae) is caused by linkage with the gametophytic self-incompatibility (S) locus

Abstract

The inheritance of leucine aminopeptidase (LAP), phosphoglucomutase (PGM), and shikimate dehydrogenase (SKD) isozymes was studied in Schlumbergera truncata and S. x buckleyi (Cactaceae). Isozymes were extracted from phylloclades and separated using polyacrylamide-gel electrophoresis. F1, F2, and BC1 populations were examined to determine the mode of inheritance. Relatively few families exhibited disturbed segregation ratios at Pgm-1 or Skd-1. In contrast, segregation ratios at Lap-1 were distorted in 14 of the 22 families that were examined. Disturbed segregation at Lap-1 was attributed to linkage with the gametophytic self-incompatibility (S) locus (recombination frequency + 7% ± 1%). Lap-1, Pgm-1, and Skd-1 assorted independently of each other. Lap-1 and S may be useful for assessing linkage conservation among self-incompatible taxa in the Cactaceae.