Physiological characteristics and genetic diversity of Lilium distichum Nakai autotetraploids

Abstract Polyploidy is widely recognized as a major evolutionary force in plants that enhances environmental adaptability and the diversity of phenotypes. Lilium dis + ichum Nakai is a rare wild diploid lily of high horticultural value that is susceptible to disease and has a low coefficient of reproduction in nature. In order to identify the chromosomes and inter-simple sequence repeats (ISSR) of this lily, we performed colchicine induction of somatic embryos, and accordingly obtained three autotetraploid genotypes. Compared with diploids, the autotetraploid L. distichum plants had larger bulbs, thicker scales, wider leaves, thicker and stronger adventitious roots, and higher starch and sugar contents. Optical microscopy revealed larger single cells and a higher number of starch grains in the autotetraploids. Furthermore, the tetraploid plants had lower proline and malondialdehyde contents and higher root activity, which we assume contributes to the enhanced resistance of tetraploids compared with diploids and would have a positive effect on field transplantation. All autotetraploid genotypes had thicker scales and better developed roots than the diploids, although we detected differences in the scales of different genotypes, with those of T3 being the most compact and those of T1 being the least compact. We also detected differences in the starch and sugar contents and physiological indices among the three genotypes, although these showed similar trends and were all superior to the corresponding traits in the diploids.