Cross-Compatibility and the Ploidy of Progenies in Crosses between Diploid and Tetraploid Cyclamen (Cyclamen persicum Mill.).

Abstract

Cross-compatibility and characteristics of F1 progenies in intraspecific crosses between diploid and tetraploid cyclamen (Cyclamen persicum Mill.) were investigated.1. Although many pollen tubes reached the ovules in reciprocal crosses between diploid and tetraploid cultivars, only a few fully developed seeds were obtained and the seedlings derived therefrom were all tetraploids.2. More fully developed tetraploidy seeds were obtained when plants such as the diploid cultivar 'Pure White' having numerous giant pollen grains are used as pollen parent. Therefore, we hypothesize that fertilization of a 2x-egg by a giant pollen grain is the mechanism whereby tetraploid progenies originate in 4x×2x cyclamen crosses.3. Progenies from crosses between diploid and tetraploid cyclamen cultivars are predicted to remain tetraploid in further generations because F2 progenies are all tetraploids.