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Scientia Silvae Sinicae ›› 2021, Vol. 57 ›› Issue (7): 61-69.doi: 10.11707/j.1001-7488.20210707

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Ploidy Identification of Camellia hainanica

Tianwen Ye1,Deyi Yuan1,Yanmin Li1,Shixin Xiao1,*,Shoufu Gong2,Jian Zhang2,Sufang Li1,Jian Luo3   

  1. 1. Key Laboratory of Cultivation and Protection for Non-Wood Forest Trees of Ministry of Education Central South University of Forestry and Technology Changsha 410004
    2. Xinyang Agriculture and Forestry University Xinyang 464000
    3. Lexiang Seedling Management Limited Company in Chengmai, Hainan Chengmai 571900
  • Received:2020-09-24 Online:2021-07-25 Published:2021-09-02
  • Contact: Shixin Xiao

Abstract:

Objective: The flower and fruit characteristics, growth and development habits of Camellia hainanica are obviously different from other Camellia species, and its ploidy is still unclear. This study uses flow cytometry and chromosome counting to clarify the ploidy of C. hainanica, which provides a basis for deployment of pollen trees and studies of genetics and breeding in the future. Method: Firstly, diploid Camellia fluviatilis var. megalantha was used as a control, and young leaf samples of 60 elite trees of C. hainanica were collected, fluorescence intensity of the DNA content of each sample was measured by flow cytometry(FCM), the ploidy of samples was estimated according to their DNA peaks. Secondly, according to the results of flow cytometry, diploid C. fluviatilis var. megalantha was used as a control, a total of 34 representative trees were selected, including different ploidy C. hainanica from different regions, and samples of root tips were collected for counting their chromosome numbers using electron microscope, so as to verify the results of flow cytometry. Result: The detection by flow cytometry showed that: The DNA peak of diploid C. fluviatilis var. megalantha was 50.39. Among the 60 samples of C. hainanica, 8 samples showed a range of DNA peak of 205.50-213.42, indicating an octoploid compared to the control, and 50 samples showed a DNA peak range of 243.16-256.11, indicating a decaploid. The DNA peaks of CMZX-612 and TCXYL-61 were 177.09 and 188.02, doubted to be a heptaploid. The coefficient of variation of the DNA peaks was less than 5% for most of the tested samples. And the chromosome counting showed that: The chromosome number of diploid C. fluviatilis var. megalantha was 2n=2x=30. Among the 34 samples of C. hainanica for testing, 8 root tip samples were octoploid(2n=8x=120), including CMZX-612 and TCXYL-61 doubted to be heptaploid detected by the flow cytometry, chromosome counting confirmed that they are actually octoploid(2n=8x=120). 26 root tip samples of C. hainanica were decaploid(2n=10x=150) detected by the chromosome counting, basically the same as those estimated by flow cytometry. Conclusion: The flow cytometry and chromosome counting both indicated that the 60 tested samples of C. hainanica had two ploidies, octoploid(2n=8x=120) and decaploid(2n=10x=150), of which decaploid accounted for 83.3%. C. hainanica is a newly discovered species of the genus Camellia, and its ploidy is obviously different from other species in Camellia. Determination of ploidy of C. hainanica provides a significant basis for further studies on inheritance and evolution of polyploidy, as well as parents selection for cross breeding and identification of germplasm resources.

Key words: Camellia hainanica, ploidy, chromosome, flow cytometry

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