Nuclear DNA content in different plant materials of Plantago asiatica L. cultured in vitro

Abstract

Flow cytometry was used to study the genome size and the cell cycle in different plant materials of Plantago asiatica (2n = 2C = 4x) cultured in vitro, including long-term callus lines. The nuclear DNA content varied from 2.97 to 3.45 pg/2C, depending on the plant material analyzed. However, in most of the cases it was similar to that of the seedling (3.3 pg), the source material. This suggests that in vitro cultures of P. asiatica produce genetically stable material. It seems that a significantly higher or lower than in a seedling leaf DNA content in callus can be an indication of the lack of its organogenic potential. Analysis of the cell cycle showed that there was no endopolyploidization in any of the seedling organs; thus P. asiatica is likely a non-polysomatic species. A high proportion of 2C nuclei (>80%; tetraploid ploidy level) was maintained in almost 70% of the calli but did not ensure their high organogenic capacity. Two out of 82 calli were octoploid and they were non-organogenic. In 30% of calli endoreplication up to 16C occurred. Since endopolyploid cells were present in organogenic as well as in non-organogenic calli, the polysomaty level of P. asiatica callus cannot be considered as an indication of its totipotency.