Cytogenetic Relationship between Allium fistulosum L. and A. schoenoprasum L.

Abstract

Interspecific hybrids between Allium fistulosum L. (2n=16) and A. schoenoprasum L. (2n=16) which are classified to different sections of the Allium were investigated cytogenetically to elucidate their relationship. Hybrid plants (2n=16) were produced by reciprocal crossings through embryo or ovule cultures, but the number of hybrid plants derived per pollinated flower was much smaller in the combination using A. fistulosum as a seed parent. At meiotic metaphase-I, chromosome parings of 161 or 1II+14I occurred frequently ; tetrads were observed together with dyads and heptads at tetrad stage. The hybrid plants exhibited three types of anther development ; a) fully developed form, b) aborted form or c) having both forms. Unreduced spherical pollen grains were observed in fully developed anthers. Pollen stainability ranged from 13 to 65%. No plant was obtained in the backcross with A. fistulosum. Chromosome doubled plants were produced through colchcine treatment of hybrid plants. In the chromosome doubled plant derived from the hybrid plant with fully developed anthers, pollen stainability was 64%. No seed was obtained through open pollination and crossing with A. fistulosum as a pollen parent. In the chromosome doubled plant derived from the hybrid plant with aborted anthers, anthers were aborted and were pollen-sterile. These results indicate that the homology between the genomes of A. fistulosum and A. schoenoprasum is low and that they are distantly related to each other cytogenetically.