GENETIC REGULATION OF HETEROGENETIC CHROMOSOME PAIRING IN POLYPLOID SPECIES OF THE GENUSTRITICUM sensu lato

Abstract

Polyploid species of Triticum s. l. were crossed with T. aestivum L. em. Thell. cv. Chinese Spring monoteloidisomics or ditelosomics that were monosomic for chromosome 5B. Progeny from these crosses were either euploid, nullisomic for 5B, monotelosomic for a given ''Chinese Spring'' chromosome, or nullisomic for 5B and monotelosomic simultaneously. The ''Chinese Spring'' telosome in the hybrids permitted the evaluation of autosyndesis of chromosomes of the tested species. In addition, several ''Chinese Spring'' eu- and aneuhaploids were produced. Genotypes of T. cylindricum Ces., T. juvenale Thell., T. triunciale (L.) Raspail, T. ovatum (L.) Raspail, T. columnare (Zhuk.) Morris et Sears, T. triaristatum (Willd.) Godr. et Gren., and T. rectum (Zhuk.) all have suppressive effects on heterogenetic pairing in hybrids lacking 5B or 3AS, whereas T. kotschyi (Boiss.) Bowden had no effect. Diploid-like meiosis in these species is due to genetic regulation. A number of these genotypes promoted heterogenetic pairing in the presence of 5B. A model is presented to explain this dichotomous behavior of the tested genotypes. Monotelosomic-3AL haploids had a greater amount of pairing than did euhaploid ''Chinese Spring'', which substantiated the presence of a pairing suppressor(s) on the 3AS arm. T. juvenale does not have a genome homologous with the D genome of T. aestivum.