Agriculture Reference
In-Depth Information
Fig. 8.3 a
A slice section of tea ovary culture, showing swollen ovules, after two weeks of culture
(8X).
b
Four-week-old cultures showing bursting of ovules and emergence of callus from within
(8X)
Anther culture studies are quite limited in coffee. The first attempt to produce
haploid coffee plants was made in
Coffea arabica
(Sharp et al.
1973
). Successful
reports of haploid and dihaploid plants from anther culture of coffee have been pub-
lished (Montes
1981
; Ascanio and Arcia
1987
). Ascanio and Arcia (
1987
) reported
the existence of a correlation between different developmental stages of anthers, the
size of flower buds and the quantity of calli obtained after 90 days of culture. Fur-
ther in 1994, the authors studied the effect of developmental stage and heat shock on
the formation of embryogenic calli from
C. arabica
var. guernica anthers.
Unlike anther culture, isolated microspore culture allows haploid plant regen-
eration directly from microspores, assuring pure gametophytic origin. Colonies of
haploid cells have been successfully obtained via mechanically isolated microspore
cultures of
C. arabica
varieties Catuai and Catimor in either liquid or solid media
(Carneiro
1997
). Herrera et al. (
2002
) described, for the first time, a new approach
for embryo induction and plant regeneration from
C. arabica
cv caturra isolated
microspores, pre-treated with colchicine. Their study clearly demonstrated that col-
chicine could activate the androgenic response in coffee microspores. A positive
androgenic development was observed only when late uninucleated or early bi-
nucleated microspores were cultured. Such response was evidenced by microspore
divisions beginning after 25 days of colchicine exposure. The best androgenic re-
sponse was found when microspores were pre-cultured in 100 mg/l colchicine for
48 h. Flow cytometry and morphological analyses revealed that 95 % of regener-
ated plants were dihaploids (2n = 2x = 22). However, some doubled dihaploid plants
(2n = 4x = 44) were also obtained, suggesting that not only androgenic induction but
also chromosome doubling could be expected as a result of colchicine exposure of
coffee microspores.
Lanaud in
1981
reported somatic embryogenesis in ovules from
C. canephora
and established conditions for rapid multiplication and differentiation of embryo-
