Plant Biotechnology Reports

, Volume 13, Issue 2, pp 141–149 | Cite as

Mechanism underlying 2n male and female gamete formation in lemon via cytological and molecular marker analysis

  • Kai-Dong Xie
  • Qiang-Ming Xia
  • Jun Peng
  • Xiao-Meng Wu
  • Zong-Zhou Xie
  • Chun-Li Chen
  • Wen-Wu GuoEmail author
Original Article Plant Molecular Biology and Biotechnology Works


The unreduced (2n) gametes have long been used in triploid breeding of citrus. In lemon, the previously reported mechanisms for 2n megagametophyte formation were controversial, whereas that for 2n pollen production is still unknown. Herein, the frequency of and mechanism underlying 2n megagametophyte and 2n pollen formation in ‘Eureka’ lemon were investigated based on cytological observation and genotyping of the triploid hybrids between ‘Eureka’ lemon and ‘Early gold’ sweet orange. As a result, 4.79% of the viable pollens of ‘Eureka’ lemon were identified as the 2n pollen with a larger diameter (70.16 ± 3.92 µm). The 2n pollen might be resulted from the formation of parallel spindles at meiosis stage II. Among the 204 plantlets regenerated from embryo rescue following the sexual cross, 12 were triploids as identified by flow cytometry. According to the analysis of heterozygosity transmission using 13 pericentromeric single nucleotide polymorphism (SNP) markers and 20 randomly distributed simple sequence repeat (SSR) markers, 11 triploids were identified to be originated from the fertilization of 2n megagametophytes of ‘Eureka’ lemon, with a frequency of 5.39%. Among them, nine 2n megagametophytes were supposed to be arisen from the second division restitution (SDR), whereas the other two were from post-meiotic genome doubling (PMD). These results to understand the mechanism underlying 2n gamete formation in lemon are valuable for its efficient polyploid breeding.


Citrus Triploid breeding Unreduced gamete SNP genotyping Second division restitution 



This research was financially supported by the National Natural Science Foundation of China (nos. 31701873, 31820103011), the Fundamental Research Funds for the Central Universities of China (nos. 2662017PY019, 2662018PY007) and the China Postdoctoral Science Foundation (2016M602320).

Compliance with ethical standards

Conflict of interest

The authors declare that they have no conflict of interest.

Supplementary material

11816_2019_525_MOESM1_ESM.docx (29 kb)
Supplementary material 1 (DOCX 28 KB)


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Copyright information

© Korean Society for Plant Biotechnology 2019

Authors and Affiliations

  • Kai-Dong Xie
    • 1
  • Qiang-Ming Xia
    • 1
  • Jun Peng
    • 1
  • Xiao-Meng Wu
    • 1
  • Zong-Zhou Xie
    • 1
  • Chun-Li Chen
    • 1
  • Wen-Wu Guo
    • 1
    Email author
  1. 1.Key Laboratory of Horticultural Plant Biology (Ministry of Education), College of Horticulture and Forestry SciencesHuazhong Agricultural UniversityWuhanChina

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