Chromosomal mosaicism in the mistletoe, Helicanthes elastica (Desr.) Danser

摘要

Chromosomal mosaicism, an abnormal mitotic phenomenon was observed in the somatic tissues of the parasitic mistletoe, Helicanthes elastica (Loranthaceae). In addition to the normal diploid karyotype, several aberrant polyploid chromosomal variants were detected. The diploid chromosome number (2n = 18) appeared with a high frequency (68%); however, variable numbers, especially of the higher euploid mode, ranging from diploidy to duo-decaploidy were present at random in cells derived from the stem tip meristematic tissues. Euploid variant chromosome numbers, viz. triploid (27), tetraploid (36), hexaploid (54), octaploid (72) and duo-decaploid (108) were observed. Aneuploid variations were not detected in the stem tip meristematic tissues. Endomitosis seems to be the probable cause for this phenomenon. This might have occurred as a result of abnormalities in the mitotic process, resulting in euploid variations. Mosaicism in H. elastica appears to be the results of abnormal functioning of mitotic spindle and doubling of chromosomal number at the end of nuclear division in the present study.