Abstract:

Induced polyploidy is nowadays an important strategy in plant breeding. To obtain new germplasm and breed new resistant varieties of Luculia pinciana, we got polyploid plants by chemical mutagenesis. The seeds of L. pinciana were soaked in different concentrations of oryzalin. The hypocotyl enlargement of seeds was regarded as the mutant, and the mutation rate and germination rate were calculated. The morphological observation, stomatal observation, chromosome count and flow cytometer were used to confirm ploidy level of diploid control and polyploid plants. The results were as follows: the highest percentage (60.1%) of polyploids was induced with 15 μmol/L oryzalin for 24 h, and two tetraploid plants were obtained. After 24 h induction with 25 μmol/L oryzalin, the mutation rate was 50%, and an octaploid plant was obtained. The polyploid plants showed different growth traits compared with those of diploid control plant; polyploid plants had leaves with a darker green color, a higher trichome density, and lower plant height. Particularly, stomata of polyploids were larger with lower density than diploids. Approximate multiple relationship of DNA content in different ploidy plants was detected by flow cytometry. The chromosome number was 2n=44 in diploids and 4n=88 in the tetraploids. The content of MDA was significantly lower than that of diploid, while the content of Pro was significantly higher than that of diploid.

Key words: Luculia pinciana, polyploid induction, oryzalin, mutation identification, chromosome, flow cytometry