Nematode Resistance Derived from Wild Beet and its Meiotic Stability in Sugar Beet

Abstract

Abstract Three different karyotypes of sugar beet with resistance against the beet cyst nematode ( Heterodera schachtii ) have been investigated. These comprised monosomic addition lines (2n = 19) with one complete chromosome from B. patellarris or B. procumbens , one line with a chromosomal fragment added to the normal sugar beet chromosome complement (2n =18 + fragment) and one diploid line (2n = 18). The fragment originated from a B. procumbens chromosome since during meiosis it formed a univalem. It carries the gene for nematode resistance. Meiotic disturbances like univalems. laggards, anaphase I bridges, fragments and micronuclei were observed in all resistant genotypes. These may result in an exclusion of the chromosome fragment carrying the resistance from the rest of the genome. In the diploid resistant line, a chromosome with a translocation could be distinguished from the other B. vulgaris chromosomes. Meiotic irregularities also appeared in diploid resistant types and are one main reason for low transmission of the resistance. Tin‐relationship between meiotic stability and the transmission rate of the resistance gene is discussed.