Cytological Characteristics of Ten-Year-Old Rye-Grass Endosperm Tissue Cultures

Abstract

A clone of perennial rye-grass (Lolium perenne L.) endosperm tissue culture, isolated in 1955, was studied after 10 years of periodic subculturing. Cytological, morphological, and growth data were obtained, which demonstrated that the tissue had remained approximately triploid (3n = 21). On the basis of chromosome counts in 392 cells, the most frequent numbers were 21 (76 counts) and 22 (77 counts). The range of chromosome numbers was 18-50. Surprisingly, only two cells were 18, four cells were 19, and 10 cells were 20 in chromosome number. Moreover, a karyotype analysis suggests that the tissue is not morphologically triploid in a strict sense, since seven triplets of homologs no longer exist. Dicentric chromosomes and fragmented chromosomes were present. The growth of the tissue, in terms of 25-day increase in wet weight, diminished by about 30% in 10 years; and its ability to synthesize starch was reduced.