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Scientia Silvae Sinicae ›› 2021, Vol. 57 ›› Issue (12): 68-78.doi: 10.11707/j.1001-7488.20211207

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Optimization of the Micropropagation Protocol of Paeonia × lemoinei 'High Noon'

Shusheng Wen1,2,Fangyun Cheng1,*,Yuan Zhong1   

  1. 1. College of Landscape Architecture, Beijing Forestry University Peony International Institute Beijing 100083
    2. College of Landscape Architecture, Nanjing Forestry University Nanjing 210037
  • Received:2021-07-02 Online:2021-12-25 Published:2022-01-26
  • Contact: Fangyun Cheng

Abstract:

Objective: Micropropagation protocols have been developed for more than 20 varieties of tree peony(Paeonia Sect. Moutan), but not applied to industrial use due to the high contamination rate, low multiplication rate, rooting difficulties and low transplanting survival rate. Therefore, it is an important issue to improve the micropropagation protocols of tree peony. Method: This study was performed to optimize the micropropagation protocol of Paeonia × lemoinei 'High Noon' through selection of explants, light-emitting diodes(LED) illumination culture and improvement of rooting methods. Result: Etiolated shoots were explants superior to scale buds which showed lower contamination rate(19.59%), higher survival rate(80.41%), and no browning during initial culture. Compared with traditional fluorescent lamp, the optimal LED illumination(light quality 70%Red+30%Blue, light intensity 50 μmol·m-2s-1) significantly promoted the multiplication and growth of the in vitro shoots. The multiplication rate was 3.79, and the in vitro shoots grew well. Based on the reactivity that vitamin B2 (VB2) can coexist with IBA under dark conditions and decompose IBA under light conditions, an efficient one-step rooting method was developed. The shoots were firstly cultured in the dark on medium supplemented with IBA 1.0 mg·L-1 and VB2 1.0-5.0 mg·L-1 for 30 days to induce rooting, and then transferred to light culture for 20 days to accelerate IBA decomposition which will help eliminate the inhibition of IBA on root elongation. The rooting percentage(71.07%-74.23%) and root number(3.17-3.34) of one-step rooting method were similar to those of two-step rooting method. Compared with two-step rooting method, the one-step rooting protocol improved the transplanting survival rate by optimizing the quality of rooted shoots, and its proportion of first grade plantlet was up to 75.00%, which produced 85.00% survival after transplanting. Conclusion: Etiolated shoots are explants superior to scale buds in initiation and establishment of in vitro culture. LED illumination(light quality 70% Red+30% Blue, light intensity 50 μmol·m-2s-1) can significantly promote the multiplication and growth of in vitro shoots. An efficient one-step rooting method was established in P. × lemoinei 'High Noon' micropropagation both by addition of vitamin B2 in the rooting medium and by the control of light conditions(30 days of dark culture, and then 20 days of light culture), which produced simpler technical process, lower rooting cost, better quality of rooted shoots and higher transplanting survival rate than two-step rooting method. This study has developed an optimized micropropagation protocol for P. × lemoinei 'High Noon', greatly promoting the micropropagation of the variety, and providing a basis for the micropropagation of other tree peony varieties.

Key words: Paeonia Sect. Moutan, micropropagation, explant, multiplication, light-emitting diodes, vitamin B2, one-step rooting

CLC Number: