Intergeneric hybridization between Hordeum and Secale II. Analysis of meiosis in hybrids

Abstract

Forty-one (41) intergeneric cross combinations between Hordeum and Secale were analysed for meiotic MI chromosome pairing. Hordeum taxa used in these hybrids included diploid, tetraploid, and hexaploid cytotypes. Differences between the sizes of the chromosomes of Hordeum and Secale allowed distinction between auto- and allosyndetic pairing. Allosyndesis was very rare, indicating lack of homology between any of the genomes of Hordeum (H, I, “X”, “Y”) and the R-genome of Secale. Autosyndetic pairing among Hordeum chromosomes occurred in the hybrids involving polyploid species of Hordeurn. The segmental alloploid nature of H. brachyantherum, H. jubatum, H. lechleri, H. arizonicum, H. procerum, H. capense. and H. secalinum was confirmed, but it is suggested that the annual H. depressum is an autotetrdploid. In general the level of autosyndetic pairing among the Hordeum chromosomes was higher in the intergeneric combinations with Secale than in corresponding Hordeum polyhaploids. It is suggested that the genome of Secale exerts influence during synaptonemal complex formation, allowing a higher level of crossing-over between the chromosomes of Hordeum.