Polysomaty and chromosome number variation in a population of Ceratophyllum demersum L. from Aquila Lake (Aspromonte Mountains, Calabria, Italy)

Ceratophyllum is a genus of perennial, freshwater plants with an essentially cosmopolitan distribution. In this study, we report for the first time, the presence of somatic polyploidy and chromosome number variation in a C. demersum population from Calabria (Italy). Observations on mitotic divisions and chromosomal behaviors as well as DNA measurements have been carried out using standard chromosome counting and Image Cytometric analysis. The estimations of DNA amounts were carried out using the interphase-peak method. Chromosome number variation was detected in different plants from the studied population, as well as in a single individual. The relative DNA value of nuclei confirmed that all the studied individuals presented polysomaty. Anomalies during the different mitotic phases were also observed. The data strongly suggest that these anomalies associated to the endoreduplication could be the cause of the several numbers detected. An attempt to compare our data with those reported in literature is discussed. However, the detection in Calabrian population of different chromosome numbers, even in a single individual, strongly suggests that a revision of karyological data in this genus seems necessary. The data reported represent the first contribution to understanding the basic cytogenetics in this genus.