STUDIES OF CHROMOSOME DISTRIBUTION IN A TRIPLOID RHOEO

The triploid Rhoeo spatacea (X=6) exhibited random distribution of the chromosomes at anaphase I, and the number of chromosomes in the gametes will range from monoploid to diploid, i.e. from 6 to 12. Among 89 pollen mother cells (PMC) without laggards, 4 (4, 49%) had 6-12 distribution, 11 (12, 36%) had 7-11, 44 (49.44%) ah 8-10 distribution which was most frequently observed, and 30 (33.71%) had 9-9 distribution. Lagging chromosomes were found in 32.06% of the 131 PMC examined. The number of laggards in PMC ranged from one to four, with one laggard being most frequently found. The observed frequencies of various types of chromosome distribution in PMC with one or two laggards also fit the calculated frequencies based on random chromosome distribution. Despite of the irregularities in the meiotic division, triploid Rhoeo demonstrated a rather high pollen viability, 45.09%, probably due to a greater tolerance of the hypermonoploid or hypodiploid pollen for changes in chromosome number and balance. © 1979 Taylor and Francis Group, LLC.