An efficient method for inducing multiple genotypes of tetraploids Lilium rosthornii Diels

Abstract

Polyploids generally show strong environmental adaptation and diverse morphological variations. Therefore, polyploid induction is an important protocol for plant breeding. Lilium rosthornii is a wild lily species with high horticultural value and excellent disease resistance. In this study, seeds of L. rosthornii were subjected to polyploidy induction treatments to obtain multiple genotypes of tetraploids. Germinated seeds were immersed in two antimitotic agents at different concentrations for various times. In total, 199 tetraploid genotypes were obtained. The most efficient treatments of each agent were immersed in 0.05% colchicine for 36 h and in 0.01% oryzalin for 24 h; the induction rate of the former (27.78%) was significantly higher than that of the latter (22.22%). The swollen hypocotyl phenotype after colchicine and oryzalin treatments was strongly correlated with tetraploidy (0.989** and 0.975**, respectively), suggesting that this phenotype could serve as an early ploidy selection trait. The correlations were weaker between stomata length/density and tetraploidy (0.773** and 0.695**, respectively), implying that stomatal characters are affected by both the ploidy level and genotype. After several rounds subculture in vitro, the morphology and growth traits were not significantly different between diploids and tetraploids, but there were wider variations in these parameters in tetraploids than in diploids. After transplanting, the bulblet germination rate was higher in tetraploids than in diploids. The leaf phenotype did not differ between tetraploids and diploids initially, but the leaves of tetraploids became larger than those of diploids over time. Together, these suggest that tetraploids, may contribute diverse characteristics to lily breeding. Multiple genotypes of tetraploid Lilium rosthornii were induced by colchicine and oryzalin. Swollen hypocotyl was associated with polyploidy. Compared with diploids, tetraploids showed wider variations in morphological parameters.