Resistance to bacterial blight in arabica coffee cultivars

No abstract

Inter-simple sequence repeat (ISSR) markers were used to evaluate genetic divergence among eight Coffea species and to identify the parentage of six interspecific hybrids. A total of 14 primers which contained different simple sequence repeats (SSR) were used as single primers or combined in pairs and tested for PCR amplifications. Two hundred and thirty highly reproducible fragments were amplified, which were then used to estimate the genetic similarity and to cluster the Coffea species and hybrids. High levels of interspecific genetic variation were revealed. The dinucleotide motif (GA) 9 T combined with other di-tri-and tetra-nucleotides produced a greater number of DNA fragments, mostly polymorphics, suggesting a high frequency of the poly GA microsatellite motifs in the Coffea genomes. The genetic similarity ranged from 0.25 between C. racemosa and C. liberica var. dewevrei to 0.86 between C. arabica var. arabica and Hybrid N. 2. The C. arabica species shared most of its markers with five of the six hybrids suggesting that it is the most likely candidate as one of the progenitors of those hybrids. These results revealed that ISSR markers could be efficiently used for genetic differentiation of the Coffea species and to identify the parentage of Coffea interspecific hybrids.

No abstract

RESUMOO objetivo desta investigação foi estudar progênies de Coffea arabica quanto a resistência à ferrugem alaranjada, causada por Hemileia vastatrix, e à mancha aureolada, causada por Pseudomonas syringae pv. garcae. O experimento foi instalado no Centro de Produção e Experimentação de Londrina, do Instituto Agronômico do Paraná. Utilizou-se delineamento em blocos ao acaso, com três repetições, 13 tratamentos (11 progênies e as testemunhas 'IAPAR 59' e 'Catuaí Vermelho IAC 81'). Os resultados sugerem investigar a possibilidade da ocorrência de novo(s) patotipo(s) de P. syringae pv. garcae no Paraná. Observou-se na cultivar 'IAPAR 59' resistência suficiente para reduzir danos provocados por P. syringae pv. garcae, causador da mancha aureolada, em regiões de alta ocorrência do patógeno no Paraná. Na progênie "Catuaí" x "Icatú" PRFB 2-27-1/F5 (IAPAR 96095) verificou-se resistência simultânea à ferrugem alaranjada e à mancha aureolada e deverá ser testada em ensaios regionais.Palavras-chave: melhoramento de café, resistência à doenças, cultivar, cafeicultura. ABSTRACT SELECTION OF PROGENIES OF COFFEA ARABICA WITH SIMULTANEOUS RESISTANCE TO BACTERIAL BLIGHT AND LEAF RUSTThis research aimed at to study C. arabica progenies as to resistances to bacterial blight "mancha aureolada", caused by Pseudomonas syringae pv. garcae, and coffee leaf rust, caused by Hemileia vastatrix. The experiment was carried out in the Centro de Produção e Experimentação de Londrina, Instituto Agronômico do Paraná. It was set in a randomized complete block design with 13 treatments (11 progenies and the controls 'IAPAR 59' and 'Catuaí Vermelho IAC 81') and three replications. The results suggest the ocurrence of new(s) pathotype(s) of P. syringae pv. garcae in Paraná State. The IAPAR 59 cultivar is an option to minimize the damage caused by P. syringae pv. garcae in areas of high incidence of this pathogen. The progeny PRFB 2-27-1/F5 (IAPAR 96095) from "Catuaí" x "Icatú" cross presented simultaneous resistance to leaf rust and to bacterial blight ("mancha aureolada"). It will be tested in future regional trials.