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vol.12 issue4-6Melhoramento do cafeeiro: V - Melhoramento por hibridaçãoGenética de Coffea: XV - Hereditariedade dos característicos principais de Coffea arabica L. Var. semperflorens K.M.C. author indexsubject indexarticles search
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Bragantia

Print version ISSN 0006-8705

Bragantia vol.12 no.4-6 Campinas Apr./June 1952

http://dx.doi.org/10.1590/S0006-87051952000200004 

Observações citológicas em Coffea. XIX - Microsporogênese em Coffea dewevrei

 

 

Dixier M. Medina

Engenheira agrônoma, Secção de Citologia, Instituto Agronômico de Campinas

 

 


SUMMARY

Coffea Dewevrei De Wild, et Th. Dur. is a diploid species with 2n = 22 chromosomes. Details on the microsporogenesis are presented in this paper.
From pachynema to diakynesis the 11 bivalents were well differentiated into achromatic and chromatic regions : the centromere was in all chromosomes surrounded by deeply chromatic zones. Only one pair of chromosomes was found to be attached to the nucleolus; it has a submedian centromere, the organizing region seeming to be located in the short arm.
Chiasmata were seen in diakynesis and metaphase I; in this later stage they were studied in detail and the chromosomes were classified as follows : a) 1 longer pair with 3 chiasmata; b) 2.7 pairs (average) with 2 chiasmata ; c) 7.3 pairs (average) with 1 chiasma.
The 2-chiasmata chromosomes were of two kinds : "symmetric" and "assymmetric", depending on the position of their chiasmata in relation to the centromere.
The anaphase is normal, pollen grains having 11 chromosomes. Very seldon are pollen grains formed with 10 or 12 chromosomes. First mitosis in the microspores occurs before pollen shedding.
It was concluded that microsporogenesis in the coffee plants studied is normal.


 

 

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LITERATURA CITADA

1.  Bachi, O. Observações citológicas em Coffea. VII — A macrosporogênese na variedade "Monosperpia". Bragantia 1: 483-490. 1941.         [ Links ]

2.  Brown, S. N. The structure and meiotic behavior of the differentiated chromosomes of tomato. Genetics 34: 437-461. 1949.         [ Links ]

3.  Krug, C. A. Observações citológicas em Coffea. III. Bol. téc. Inst, agron. Campinas 27: 1-19. 1937.         [ Links ]

4.  Medina, Dixier M. Observações citológicas em Coffea. XIV — Microsporogênese em Coffea arabica L. var. rugosa K.M.S. Bragantia 10: 61-66, fig. 1. 1950.         [ Links ]

5.  Mendes, A. J. T. Observações citológicas em Coffea. XII — Uma nova forma tetraplóide. Bragantia 9 : 25-34. 1949.         [ Links ]

6.  Mendes, A. J. T. Observações citológicas em Coffea. XV — Microsporogênese em Coffea arabica I,.. Bragantia 10: 79-87, fig. 1-2. 1950.         [ Links ]

7.  Mendes, C. H. T. Observações citológicas em Coffea. XVI - Microsporogênese, em Coffea canephora Pierre ex Froehner. Bragantia 10: 97-104, est. 1. 1950.         [ Links ]

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