Accessory Chromosomes of Aster ageratoides subsp. sugimotoi

Abstract

Accessory chromosomes were found in Aster ageratoides subsp. sugimotoi collected at Mt. Akiba, Shizuoka Pref. About 46% of the 35 clones studied had accessory chromosomes varing from 1 to 4 in number. The accessory chromosomes of this species showed variation in length and in the position of the primary constriction. These chromosomes could be classified into 7 types. Each of the accessory chromosomes, the standard, primary derivative cp and secondary derivative aS, was found to pair with each other at meiosis in PMCs. The standard accessory chromosome of this species was the longest among the accessory chromosomes and possessed a primary constriction located in the subterminal position. The other accessory chromosomes were presumed to be derivatives of the standard accessory chromosome. Differentiation among the 7 types of the accessory chromosomes is discussed (Fig. 6).