Chromosome Number Variation of Callus Cells and Regenerated Plants in Asparagus officinalis L.

Chromosome number of the plants regenerated directly from lateral bud and shoot tip of asparagus (Asparagus officinalis L.) was stable (2n=20). In callus cells induced from lateral bud on MS medium supplemented with 10μM NAA and 1μM BA, chromosome number varied widely and the range of the variation differed with the explants used. By continuing the callus culture, chromosome number in GK and 56×22p callus cells had a tendency to increase still more. GK and 56×22p calli included plenty of middle and large-sized callus cells in addition to small-sized cells. In some callus cells, multiple nuclei were observed and as is expected to occur in irregular cell division, which is surmised to be one of the causes which leads to the increase in chromosome number. Most of the plants regenerated from 56×22p callus were normal in chromosome number, but some aneuploid and polyploid plants were regenerated. While, in MW500W calli, marked increase of chromosome number was not observed and these small cells divided vigorously. All of the plants regenerated from MW500W callus showed normal chromosome number (2n=20).