In vitro tetraploid induction and plant regeneration of Pinellia ternata, a pearl-like herb

Abstract

Pinellia ternata (Thunb.) is a widely used Chinese medicinal herb in many countries globally. However, asexual reproduction causes the germplasm of P. ternata to degrade, and there is limited research on genetic breeding. The objective of this study is to induce tetraploid ‘Pearl’ P. ternate plants by treating leaves and tubers with colchicine to acquire superior germplasm resources. The in vitro medium for autotetraploid plants was optimized through orthogonal experiments. Subsequently, the morphology, tissues, and cells of diploid and tetraploid plants were compared. The results indicated that the number of chromosomes in diploid plants was 2n = 2x = 66, while the tetraploid plants were 2n = 4x = 132 by somatic chromosome counting and flow cytometry analysis. The leaf was more suitable than the tuber for polyploid induction, and the maximum induction rate was 29.49% when leaves were treated with a 0.05% colchicine solution for 96 h. In MS medium supplemented with 0.1 mg·L− 1 6-BA, 0.1 mg·L− 1 NAA, and 1.0 mg·L− 1 KT, tetraploid leaves successfully developed into plantlets with roots, achieving a 100% transplant survival rate. Tetraploid P. ternata exhibited larger and denser leaves, thicker petioles, and larger stomata but had shorter plants compared to diploid. Meanwhile, tetraploid leaves produced a greater number of tubers. This study induced tetraploids in P. ternata and established an artificial tetraploid rapid propagation system for P. ternata. It provided the theoretical foundation and experimental support for its genetic breeding and variety enhancement.