In vitro and cutting propagation of Heuchera: rapid mass production protocol and correlation between initiating ability the two methods

Abstract

There is still a lack of understanding about the efficient mass propagation of multiple Heuchera cultivars leading to a large market gap. And there has been no empirical research on the relationship between propagation methods of cutting and in vitro. In this study, thirteen different cultivars from the genus Heuchera and Heucherella (Heuchera × Tiarella) were successfully rooted by cutting, and calluses and shoots were also successfully inducted from petiole in vitro culture. However, measured indexes varied significantly among cultivars for cutting and tissue culture. Petiole explants treated with cytokinin 6-benzylaminopurine (BA: 0.5 ~ 2.0 mg/L) plus auxin α-naphthaleneacetic acid (NAA: 0.5 mg/L) formed shoots either directly or indirectly during primary culture. And the dark treatment and 2,4-dichlorophenoxyacetic acid (2,4-D) were ineffective for shoot formation but beneficial for callus stimulation. Furthermore, we discovered a negative correlation between initiating cutting recovery and tissue culture inducting, implying that cultivars with low difficulty in cutting initiating were relatively difficult to tissue culture. Then, we developed a simple and efficient Heuchera rapid propagation protocol. That is, micropropagation through obtaining adventitious shoots directly from primary cultures, supplemented by cutting propagation. Our petiole explants system and leaf-cutting technique are expected to guide Heuchera's mass production.