ABSTRACT
Cnidium officinale is a medicinal plant cultivated for its rhizomes, which are used in Chinese, Japanese, and Korean traditional medicine. This medicinal crop is highly susceptible to heat stress and cannot be cultivated in regions of higher temperatures. In the present study, ten clones from Korea (clones 1, 2, 5, 6, 8, 11, 14, 15, 22, and 26) were evaluated for their heat tolerance in vitro at 25, 30, 32.5, and 35 °C, and growth characteristics including plant height, the number of leaves and roots were evaluated. The initial experiment was conducted to find the threshold level for significant damage to the plant, while the second experiment was to screen the germplasm to select heat-tolerant clones. Most of the clones were sensitive to heat stress (clones 1, 2, 8, 11, 14, 15, 22, and 26), and few clones (clones 5 and 6) could perform well at an elevated temperature of 32.5 °C. Molecular analysis of the expression of heat-responsive genes, including heat shock protein (CoHSP), catalase (CoCAT), and cystine protease (CoCP), was performed by quantitative real-time reverse transcriptase polymerase chain reaction (qRT-PCR) carried out with heat-tolerant and heat-sensitive clones. Two of the heat-tolerant clones (clones 5 and 6) showed significant expression of CoHSP and CoCAT genes at elevated temperature treatment. These clones can be used for further evaluation and cultivation.
ABSTRACT
Cnidium officinale is a valuable medicinal plant cultivated in Asia for its rhizomes. This study reports the in vitro regeneration of Cnidium officinale plants and the induction of rhizomes from microshoots. The rhizomatous buds of Cnidium officinale induced multiple shoots on Murashige and Skoog (MS) medium supplemented with 0.5 mg L-1 BA, which led to the regeneration of plants within four weeks of culture. After four weeks of culture, the plants were assessed for fresh weight, the number of leaves, the number of roots, and the length of roots to compare the performance of the different clones. The clones with good growth characteristics were selected with the aid of a flow cytometric analysis of 2C nuclear DNA content. The plants bearing high DNA values showed better growth characteristics. Various factors, namely, sucrose concentration (30, 50, 70, and 90 g L-1), ABA (0, 0.5, 1.0, and 2.0 mg L-1), the synergistic effects of BA (1.0 mg L-1) + NAA (0.5 mg L-1) and BA (1.0 mg L-1) + NAA (0.5 mg L-1) + ABA (1.0 mg L-1) with or without activated charcoal (1 g L-1), and light and dark incubation were tested on rhizome formation from microshoots. The results of the above experiments suggest that MS medium supplemented with 50 g L-1 sucrose, 1.0 mg L-1 ABA, and 1 g L-1 AC is good for the induction of rhizomes from the shoots of Cnidium officinale. Plantlets with rhizomes were successfully transferred to pots, and they showed 100% survival.
