Breeding behavior of an autotriploid in Hyoscyamus muticus L.

Abstract

Breeding behavior of an autotriploid Hyoscyamus muticus (3n=3x=42) was determined by studying the meiotic chromosome constitution of the 122 plants from 3n-selfed and 2n×3n and 3n×2n crosses. Of these, 109 (89.3%) were diploids with 28 chromosomes and 13 (10.7%) were aneuploids with 29 to 32 chromosomes. The recovery of only 32 as the highest chromosome number in the progeny suggested that the maximum number of extra chromosomes tolerated by this species is four. The aneuploids with up to four extra chromosomes were obtained only in the progeny of 3n-selfed and 3n×2n cross indicating female transmission of the extra chromosomes. Of the 13 aneuploids in the progeny of autotriploid, six plants with 29 chromosomes, four plants with 30 chromosomes, one plant with 31 chromosomes and two plants with 32 chromosomes were positively identified as single primary trisomics (2n+1), double primary trisomics (2n+1+1), triple primary trisomic (2n+1+1+1) and quadruple primary trisomics (2n+1+1+1+1), respectively, on the basis of their meiotic chromosome pairing behavior. The 3n×2n cross produced higher percentage of single primary trisomics than did 3n-selfed.