Abstract
Korean pine (Pinus koraiensis Sieb. et Zucc.) is a critical coniferous species ecologically. In addition, its fruits have numerous nutraceutical properties and its wood is high quality timber. However, this plant has a low propagation rate and is under risk of extinction. To accelerate breeding of the excellent seedlings and selection from Korean pine, determining methods to increase the number of Korean pine trees successfully is imperative. In this present study, using sprouted seeds as the initial explants, the de novo organogenesis system for this coniferous species has been successfully developed. After 30 days of incubation on Gupta and Durzan (DCR) medium containing 2 mg L−1 kinetin (KT) and 0.5 mg L−1 thidiazuron (TDZ), 92.67% of explants produced direct buds with an average of about 15 buds per explant. We confirmed the organogenic regeneration pattern by a scanning electron microscopy (SEM). For bud elongation after 60 days of culture, we obtained the highest mean length of 34.99 mm on DCR basal media supplemented with 6-benzyladenine (6-BA, 0.2 mg L−1), 1-naphthaleneacetic acid (NAA, 0.1 mg L−1), and activated charcoal (AC, 1 g L−1). The highest rooting rates of 20.74 and 21.48% were obtained within two months of culturing on 1/2 DCR medium (halved major elements) supplemented with 0.05 mg·L−1 NAA and 0.5 or 1 mg ·L−1 indole-3-butyric acid (IBA), respectively. Rooted shoots showed a survival rate of 90.28% after acclimatization in the substrate consisting of perlite, peat, and vermiculite (1:1:1). This protocol is a successful and efficient biotechnological approach to the micropropagation of Korean pine, and the results will be helpful to the clonal propagation and conservation of Korean pine.
Highlights
Korean pine (Pinus koraiensis Sieb. et Zucc.) is an evergreen coniferous tree species belonging to the Pinus genus and Pinaceae family, a dominant species of the natural mixed coniferous and broadleaf forests in the temperate forests of Northeast China
Direct organogenesis occurred in Korean pine was observed (Figure 1)
Our results indicate that the complementary of low concentration of 6-BA and Naphthaleneacetic acid (NAA) was efficient for promoting rapid growth and elongation of shoots in Korean pine
Summary
Korean pine (Pinus koraiensis Sieb. et Zucc.) is an evergreen coniferous tree species belonging to the Pinus genus and Pinaceae family, a dominant species of the natural mixed coniferous and broadleaf forests in the temperate forests of Northeast China. There are few natural populations of Korean pine sporadically distributed in South Korea, North. Korean pine is famous for its high economic value, such as producing good quality timber and food for humans due to its riching in unsaturated fatty acids, proteins, carbohydrates, vitamin E, and other mineral nutrients. The natural populations of Korean pine have drastically declined, and the genetic resources of the species have been threatened by deforestation. Korean pine has been classified as a rare and nationally endangered species in China (Yu et al 2011; Sun et al 2016). Determining methods to increase the number of Korean pine trees in forests successfully is essential for improving qualified seedlings.
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