Morphological, Cytological, and Molecular Comparison between Diploid and Induced Autotetraploids of Callisia fragrans (Lindl.) Woodson

Abstract

The objective of the current study was to assess the efficiency of oryzalin in inducing polyploids in Callisia fragrans (Lindl.) Woodson by in vitro polyploidization. Shoot tips were subjected to Murashige and Skoog (MS) medium containing oryzalin at concentrations 1, 5, and 10 μM for 4 and 8 weeks. Further, the ploidy levels of the plants were confirmed using flow cytometry and chromosome counting. Among all treatments, six tetraploid plants (2n = 4x = 24) were obtained after 8 weeks in MS medium containing 5 μM oryzalin. Upon ex vitro transfer, tetraploid plants were morphologically distinct compared to diploid plants. The size of the leaf and flower increased significantly and nearly doubled when compared to the mother diploid plant. Further, inductively coupled plasma–optical emission spectrometry showed that tetraploid plants exhibited significantly higher sodium, iron, and calcium content, and the potassium content was increased by 100%. Molecular analysis utilizing iPBS and CDDP markers was tested for the first time in C. fragrans to assess the variation between tetraploid and diploid genotypes. Both the markers generated three major clusters, indicating a clear distinction between diploid, tetraploid, and the mixoploid genotypes. In conclusion, in vitro polyploidization using oryzalin could effectively induce polyploids in this and related species. Additionally, the results obtained in this study will provide a basis for future breeding opportunities in this species.