Microsporogênese em um híbrido tri-plóide de Coffea racemosa lour. x C. arábica L.

Abstract

"Um híbrido natural de Coffea racemosa Lour. (2n= 22) e C. arabica L. (2n= 44) apresentou-ae com característicos intermediários entre as duas espécies e quase completamente estéril. Trata-se de planta triplóide (2n= 33), na qual se estudou a microsporogênese a fim de comparar com outros híbridos triplóides de C. arabica e C. canephora. A freqüência dos trivalentes é menor no híbrido com racemosa do que no híbrido com canephora; por outro lado, os bivalentes são mais freqüentes no híbrido com racemosa. Outras particularidades da microsporogênese são apresentadas e discutidas, porém, chega-se à conclusão de que há necessidade do conhecimento citológico e genético de outros híbridos antes que se possa confirmar ou não a posição taxonômica das espécies de café.

Relationship between meiotic instability and fertility in F2 generation Arabusta coffee plants

“…Many of the irregularities reported in the process of meiotic division in this study were also found in other studies with coffee hybrids, such as C. racemosa and C. arabica (Medina 1963), C. arabica and C. kapakata (Mônaco and Medina 1965), C. dewevrei and C. eugenioides, C. liberica and C. eugenioides (Reddy and Narayan 1981), and C. arabica and C. canephora (4x) (Owuor 1985;Boaventura and Cruz 1987). Furthermore, some meiotic abnormalities observed in the F 2 population could also reflect the doubling of the single diploid C. canephora genome or incompatibility caused by genomic divergence between their parents.…”

“…Hybrids between the species C. arabica and C. canephora have been obtained on different occasions, and they are called "Arabusta" (Mendes 1950). Because of its importance, meiotic behavior had already been studied to some F 1 hybrids and also to parental plants in order to explore the genetic resources of these hybrids (Mendes 1950;Medina 1952;Medina 1963;Mônaco and Medina 1965;Medina and Rijo 1969;Reddy and Narayan 1981;Owuor 1985;Boaventura and Cruz 1987;Boaventura 1990).…”

Unraveling the origin of Coffea arabica ‘Bourbon pointu’ from La Réunion: a historical and scientific perspective

“…Its meiotic behaviour is diploid-like (Medina 1950;Mendes 1950;Mendes et al 1954;Grassias and Kammacher 1975). Presence of two genomes in ARA has been suggested from the meiotic behaviour of haploids (Berthaud 1976;Carvalho 1952;Vishveshwara 1960) and F1 hybrids (at triploid, tetraploid and hexaploid levels) between this species and other CoVea species (Berthaud 1978;Chinnappa 1968;Kammacher and Capot 1972;Louarn 1976;Medina 1963;Monaco and Medina 1965). The presence of a C. eugenioideslike genome as female parent of ARA has been emphasized from chloroplast DNA sequence comparisons (Berthou et al 1980;Cros et al 1998).…”

Cytology of a Spontaneous TriploidCoffea CanephoraPierre ex Froehner

“…Triploid forms in the genus Colfea have been reported to arise as a result of crosses between tetraploid and diploid species (CRAMER 1957;KRuG and CARVALHO 1952;MENDES 1947;MEDINA 1963;SYBENGA 1960;ANo-NYMOUS 1957). Artificial production of such hybrids is always aimed at combining economic characters found in different species.…”