Taxonomia de Coffea arabica L. III - Coffea arabica L. var. anormalis
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1950-11
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Instituto Agronômico (IAC)
Resumo
A espécie Coffea arabica L. é polimorfa ; vinte e cinco variedades e quatro formas já se acham descritas. As formas homozigotas para fatores genéticos novos estão sendo descritas como variedades, não se considerando como tais as numerosas recombinações, obtidas no decurso dos trabalhos relativos à genética dessa espécie. Em 1938, observou-se, na Estação Experimental Central de Campinas, uma nova variação de café, caraterizada por fôlhas e ramificação anormais. Essa variação foi encontrada na progênie correspondente à segunda geração de um cafeeiro normal, o que faz supor que se tenha originado por mutação. A progênie obtida pela autofecundação artificial das flores dessa variação revelou ser esta heterozigota para um par de fatôres genéticos que ainda não havia sido descrito na espécie C. arabica. A forma homozigota para êsse fator genético constitui a nova variedade anormalis, descrita no presente trabalho. Seus caracteres são comparados com os da variedade typica. A ramificação do anormalis é bastante anormal, havendo excesso de ramos ortotrópicos. Também é anormal a ramificação lateral. As fôlhas são extremamente variáveis quanto à forma e tamanho, mostrando-se ora com dois ou mais ápices, ora recortadas a diferentes profundidades ou até mesmo na base do pecíolo. O número de fôlhas por verticilo varia de 1 a 4 ; as estipulas interpeciolares são grandes, irregulares e em número de duas. As flores mostram anomalias em tôdas as suas partes. Os frutos são de tamanho normal e com disco pouco mais desenvolvido do que na var. typica ; as sementes do tipo "concha" ocorrem com frequência elevada. Outra variação semelhante ao anormalis foi encontrada no município de Avaré, onde também provavelmente apareceu por mutação. As provas genéticas até agora realizadas parecem indicar que se trata da mutação do mesmo fator genético que determina os caracteres do anormalis encontrado em Campinas.
The almost completely autogamous species Coffea arabica L. is polymorphic, twenty five varieties and four forms having already been described. The homozygous types for new genetic factors are considered new varieties, but recombinations of already known genes are not described as such. In 1938 a coffee plant was found at the Central Experiment Station coffee nursery, which showed abnormal leaves and irregular branching. As this variant appeared in a F2 population derived from a normal coffee plant, it is supposed to have originated by mutation. A study of the progeny of this mutant, obtained through artificial selfpollination, revealed that it is heterozygous for one pair of genes, which so far had not been encountered in C. arabica. Plants homozygous for this gene are described in the present paper as a new variety, anormalis. The branching habit of the anormalis variety is very abnormal, showing an excess of orthotropic branches arising at various nodes. The lateral branches are also abnormal. The leaves are extremely variable in shape and size ; sometimes they have two apices ; others are deeply incised often to the base of the petiole. The number of leaves at each node may vary from 1 to 4 ; the stipules, located between the insertion regions of the petioles, are large and irregularly shaped. The flowers show abnormalities in all their organs. The fruits are usually normal in shape and have a rather large disc. Abnormal seeds, of the "shell" (concha) type, frequently occur. A similar abnormal coffee plant was also found in a field planting in the Avaré county. It seems probable that it also arose through mutation and that it possesses the same gene which determines the characters of the anormalis variety found in Campinas.
The almost completely autogamous species Coffea arabica L. is polymorphic, twenty five varieties and four forms having already been described. The homozygous types for new genetic factors are considered new varieties, but recombinations of already known genes are not described as such. In 1938 a coffee plant was found at the Central Experiment Station coffee nursery, which showed abnormal leaves and irregular branching. As this variant appeared in a F2 population derived from a normal coffee plant, it is supposed to have originated by mutation. A study of the progeny of this mutant, obtained through artificial selfpollination, revealed that it is heterozygous for one pair of genes, which so far had not been encountered in C. arabica. Plants homozygous for this gene are described in the present paper as a new variety, anormalis. The branching habit of the anormalis variety is very abnormal, showing an excess of orthotropic branches arising at various nodes. The lateral branches are also abnormal. The leaves are extremely variable in shape and size ; sometimes they have two apices ; others are deeply incised often to the base of the petiole. The number of leaves at each node may vary from 1 to 4 ; the stipules, located between the insertion regions of the petioles, are large and irregularly shaped. The flowers show abnormalities in all their organs. The fruits are usually normal in shape and have a rather large disc. Abnormal seeds, of the "shell" (concha) type, frequently occur. A similar abnormal coffee plant was also found in a field planting in the Avaré county. It seems probable that it also arose through mutation and that it possesses the same gene which determines the characters of the anormalis variety found in Campinas.
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KRUG, C. A.; CARVALHO, A.; MENDES, J. E. T. Taxonomia de Coffea arabica L. III - Coffea arabica L. var. anormalis. Bragantia, Campinas, v. 10, n. 11, p. 335-343, 1950.