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Acta Agronomica Sinica ›› 2020, Vol. 46 ›› Issue (7): 1076-1086.doi: 10.3724/SP.J.1006.2020.94159


Biological characteristics and cytological studies on anther abortion of male sterile Camellia crassocolumna

JIANG Hui-Bing,YANG Sheng-Mei,LIU Yu-Fei,TIAN Yi-Ping,SUN Yun-Nan,CHEN Lin-Bo,TANG Yi-Chun()   

  1. Tea Research Institute, Yunnan Academy of Agricultural Sciences / Yunnan Provincial Key Laboratory of Tea Science, Menghai 666201, Yunnan, China
  • Received:2019-10-24 Accepted:2020-03-24 Online:2020-07-12 Published:2020-04-14
  • Contact: Yi-Chun TANG E-mail:tyc188@126.com
  • Supported by:
    National Natural Science Foundation of China(31760224)


The purpose of this study was to explore the flower morphology, anther and pollen abortion time and its cytological characteristics in male sterile plants of C. crassocolumna. The flowering process, floral morphology, anther structure, meiosis and microsporogenesis of male sterile (M350) and fertile plants (M352) of C. crassocolumna were observed by stereomicroscopy, paraffin section, chromosome preparation and DAPI staining. The results showed that the wild tea plant had a perfect flower, its anthers were tetrasporangiate shaped like a butterfly, with an anther wall development of basic type. It tapetal cells were binuclear, forming secretory cells at the tetrad stage, and degrading during mononuclear pollen stage. After the meiosis I, meiosis II and cytokinesis, pollen mother cells developed into tetrahedral tetrads. Microspores were triangular, and mature pollen was two-celled. The stamens of male sterile flowers developed normally in the early stage of flower bud development, and there was no difference between sterile and fertile flowers, while in the late stage of flower bud development, filaments were curved, anthers adhered and shriveled, anthers could not release pollen. The tapetal cells of male sterile flowers were proliferation abnormally and disordly at the meiosis of stage pollen mother cells, and the degradation of tapetum was delayed during the mononuclear and binucleate pollen periods. During meiosis of pollen mother cells of male sterile flowers, there were some abnormal appearances, such as chromosome ring, lagging chromosomes, chromosome bridges, chromosomal deletion, scattered chromosomes, unequal separation, micronucleus and abnormal tetrad. In sterile plants, the microspore cytoplasm was disorder, pollen grains adhered to each other at the mononuclear stage, pollen wall crumpled and deformed, cytoplasm and nucleus of pollen were blurred, the mature pollen cells were hollow and sunken. Taken together, the floral organ morphology of male sterile plants in C. crassocolumna belongs to stamen collapse type and anther abnormality type. The development of anthers is blocked from meiosis of pollen mother cells to uninucleate pollen stage, belonging to pollen mother cell abortion type and uninucleate pollen abortion type. Mononuclear period is the main period of anther abortion. Tapetum degradation delayed, chromosomal abnormalities of pollen mother cells in meiosis, and abnormal development of microspores and pollens, might be the main reasons for anther abortion in male sterile plants of C. crassocolumna.

Key words: Camellia crassocolumna, male sterility, anther, morphology, cytology

Fig. 1

Flower morphology of fertile plant M352 and male sterile plant M350 A: fertile plant M352; B: male sterile plant M350."

Table 1

Comparison of flower traits between fertile plant M352 and male sterile plant M350"

of corolla (cm)
Length of petal (cm)
Width of petal (cm)
Length of out thrum (cm)
Length of inside thrum (cm)
Length of style (cm)
Number of stamen (No.)
Fertile plant M352
7.28±0.57 a 3.53±0.30 a 2.80±0.24 a 1.66±0.18 a 0.94±0.18 a 1.61±0.18 a 190.62±16.37 a
Sterile plant M350
6.94±0.51 a 3.20±0.28 a 3.07±0.34 a 1.37±0.13 b 0.65±0.14 b 1.73±0.21 a 184.85±18.52 a

Fig. 2

Comparison of buds development between fertile plant M352 and male sterile plant M350 A-E: fertile plant M352; F-J: sterile plant M350. A and F: pollen mother cell stage; B and G: meiotic stage; C and H: uninucleate stage; D and I: binucleate stage; E and J: flowering stage."

Fig. 3

Anther pollen development process of fertile plant M352 A: spore-forming cell stage; B: pollen mother cell stage; C: meiosis stage; D: tetrad stage; E: uninucleate stage; F: binucleate stage; G and H: mature stage. Ep: epidermis; En: endothecium; ML: middle layer; T: tapetum; Sc: sporogenous cell; Pmc: pollen mother cell; Tds: tetrads; Mpg: mononuclear pollen grain; Bpg: binuclear pollen grains; Pg: mature pollen grain."

Fig. 4

Anther abortion process of male sterile plant M350 A: spore-forming cell stage; B: pollen mother cell stage; C: meiosis stage; D: tetrad stage; E: uninucleate stage; F: binucleate stage; G and H: mature stage. Ep: epidermis; En: endothecium; ML: middle layer; T: tapetum; Sc: sporogenous cell; Pmc: pollen mother cell; Mc: meiotic cell; Tds: tetrads; Mpg: mononuclear pollen grain; Bpg: binuclear pollen grains."

Fig. 5

Normal meiosis of pollen mother cells of fertile plant M352 A: interphase I ; B: prophase I leptotene; C: prophase I zygotene; D: prophase I pachytene; E: prophase I diplotene; F: prophase I diakinesis; G: metaphase I ; H: anaphase I ; I: telophase I; J: prophase II; K: metaphase II; L: anaphase II; M: tetrahedral II; N: tetrad stage; O: asynchronism meiotic."

Fig. 6

Abnormal meiosis of pollen mother cells of male sterile plant M350 A-C: annular and clavate univalent; D-G: multi-chromosome bridges and single chromosome bridge; H-K: laggard chromosomes; L: deletion chromosomes; M-P: scattered chromosomes; Q and R: meiotic asynchronous; S: mis-orientated chromosomes; T-V: micronucleus; W: trisomy; X and Y: polynuclear tetrad."

Table 2

Frequency of abnormal chromosome behavior in meiosis of fertile plant M352 and male sterile plant M350"

Meiosis stage
可育株M352 Fertile plant M352 雄性不育株M350 Male sterile plant M350
Number of cells examined
Number of
abnormal cells
Frequency (%)
Number of cells examined
Number of abnormal cells
前期I Prophase I 177 20 11.30 205 47 22.93
中期I Metaphase I 90 16 17.78 97 36 37.11
后期I Anaphase I 87 13 14.94 92 44 47.83
末期I Telophase I 113 16 14.16 124 52 41.94
前期II Prophase II 98 12 12.24 108 48 44.44
中期II Metaphase II 72 11 15.28 93 33 35.48
后期II Anaphase II 93 12 12.90 105 40 38.10
末期II Telophase II 85 9 10.59 95 32 33.68
四分体时期 Tetrad 198 27 13.64 220 97 44.09

Fig. 7

Comparison of microspores development between fertile plant M352 and male sterile plant M350 A-E: fertile plant M352; F-J: sterile plant M350. A and F: tetrad stage; B and G: early uninucleate stage; C and H: uninucleate stage; D and I: later uninucleate stage; E and J: binucleate stage."

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