Avaliação da resistência genética à ferrugem (Hemileia vastatrix Berk. et Br.) em cafeeiros F1 de RC oriundos do cruzamento Híbrido de Timor x Catuaí
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2001-11
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Revista Ceres
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Neste trabalho, objetivou-se estudar a resistência genética ferrugem em híbridos F1 e Rei provenientes de combinações entre o Híbrido de Timor (originado do cruzamento interespecifico de Coffea arabica com Coffea carzephora) e o cultivar Catual (G. arabica ). C} trabalho foi realizado nos meses de fevereiro e março de 1X98. Foram avaliados, quanto reaçao à ferrugem, os 1 t progenitores (6 Híbridas de Timor: UFV ã7'ó,2, UFV 427-15, tJFV 439-2, UFV X40-22, UFV 445-4b e CIFC 832-i; e 5 Catuai: UFV 2143-193, UFV 2I43-236, UFV 2 44-32, UFV X144-35 e UFV 2144-36), due serviram de testemunhas, os 18 híbridos F1 e os I 07 híbridos RCS provenientes de suas combinaçcães, totalizando I36 tratamentos. Para avaliação da resistência genetica das plantas, foi realizado o teste em discos de falhas (16 discos de cada amostra). Cada disco foi inoculada com aproximadamente 1 mg de uredosporos da raça II de I1. vastatrix Berk. et Br.. As reaçães foram avaliadas 49 dias após a inoculatAo. Foi adotada a seguinte escala: 1- resistente, sem qualquer sinal de infecçâo; 2- resistente, com reação de hipersensibilidade ou com clorose e ausência de esporos; e 3- susceptivel, corn presença pie pústulas uredospóricas. O método de avaliaçdes em discam de folhas em laboratório foi eficiente, com reduzida perda de discos (em média, 0,81 disci por gerbox). Das 10? plantas RCS avaliadas, 81 foram resistentes e apenas 26 apresentaram-se susceptiveis á doença Além das testemunhas Catuai, observou-se queo Híbrida de Timor UFV 427-15 também mostrou-se susceptível â ria estudada, sendo susceptiveis todas as seis plantas RCS provenientes cie seus cruzamentos. Os híbridos F1, provenientes de combinações entre Catuai e Híbrido de Timor, apresentardtn resistência raça Ti, com exceção da híbrido UFV 415-2. Dentre as plantas RC1 resistentes, tomando-se também dor base outras características observadas no campo, siarão selecionadas aquelas que seguïrdo no programa de melhoramento, nesta linha de pesquisa
A backcross breeding was conducted to transfer leaf mst resistance genes from resistant hybrids to eomrnercíai cultivars of coffee trees. The genetic resistance of F; hybrid and BC; plants Born a crossing of Timor Hybrid (Cofee arabica x Cofea canephora) and Catuai (C. arabica) were studied. The experiment was conducted from February to March 1998, using leaf discs. After ieaf washing, 16 leaf dises &om web of 136 plants were placed (abaxial side up) in a gerbox. Race Ii of Hemileia vastarrâx was used becaese of its prevalence in the ãeld. Each disc was inoculated with approximately 1 mg of uredospores. Timor Hybríds (UFV 376-2, UFV 445-46, UFV 439-2, UFV 440- 22, CIFC 832-1, and UFV 427-15) and Cantai (UFV 2143-193, UFV 2143-236, UFV 2144-32, UFV 2144-35, and 2144-36) were used' as control. After 49 days, the disease symptoms were scored as the following 3 classes: l- resistant, without symptoms; 2- resistant, with incompatibility reaction or with formation of chlorotíe Spots without sperulation; and 3- susceptible, with large pustules with sporulation. All Catuaí controls were susceptible (class 3). With exception of UFV 427-15, all Timor Hybrid were resistant (class 1 or 2),: All F; hybrid cresses were resistant, with exception of UFV 415-2. Eighty-one out of 107 BC; plants were resistant (23 of class 1 and 58 of class 2). Twenty-six out of ' 10? were susceptíble (class 3), including all 6 EC; plants originated from UFV 427-15. Resistant BC; plants with superior field perfomance were selected for breeding purposes.
A backcross breeding was conducted to transfer leaf mst resistance genes from resistant hybrids to eomrnercíai cultivars of coffee trees. The genetic resistance of F; hybrid and BC; plants Born a crossing of Timor Hybrid (Cofee arabica x Cofea canephora) and Catuai (C. arabica) were studied. The experiment was conducted from February to March 1998, using leaf discs. After ieaf washing, 16 leaf dises &om web of 136 plants were placed (abaxial side up) in a gerbox. Race Ii of Hemileia vastarrâx was used becaese of its prevalence in the ãeld. Each disc was inoculated with approximately 1 mg of uredospores. Timor Hybríds (UFV 376-2, UFV 445-46, UFV 439-2, UFV 440- 22, CIFC 832-1, and UFV 427-15) and Cantai (UFV 2143-193, UFV 2143-236, UFV 2144-32, UFV 2144-35, and 2144-36) were used' as control. After 49 days, the disease symptoms were scored as the following 3 classes: l- resistant, without symptoms; 2- resistant, with incompatibility reaction or with formation of chlorotíe Spots without sperulation; and 3- susceptible, with large pustules with sporulation. All Catuaí controls were susceptible (class 3). With exception of UFV 427-15, all Timor Hybrid were resistant (class 1 or 2),: All F; hybrid cresses were resistant, with exception of UFV 415-2. Eighty-one out of 107 BC; plants were resistant (23 of class 1 and 58 of class 2). Twenty-six out of ' 10? were susceptíble (class 3), including all 6 EC; plants originated from UFV 427-15. Resistant BC; plants with superior field perfomance were selected for breeding purposes.
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Coffea arabica, C. canephora, Ferrugem do cafeeiro, Resistência à doença