Abstract MGS Guaiçara e MGS Vereda are resistant to Meloidogyne paranaensis, one of the most aggressive nematode parasites of coffee. MGS Vereda is an early maturation cultivar, whereas MGS Guaiçara has a medium maturation cycle. Both cultivars produce red fruit, have high size, and high yield potential in infested areas.

RESUMO: Com o objetivo de investigar o grau de parasitismo de duas populações de Meloidogyne exigua, o índice de galhas (IG) e o fator de reprodução (FR) de M. exigua raças 1 (Est E2) e 2 (Est E1) foram analisados em 47 progênies na geração F3:4 ou F4:5, derivadas do cruzamento entre Coffea arabica cv. Catuaí Amarelo e Híbrido de Timor. Plantas de C. canephora cv. Apoatã IAC 2258 e C. arabica cv. Catuaí Vermelho IAC 144 foram usadas como padrão de resistência e de suscetibilidade, respectivamente. Os genótipos que foram classificados como resistentes ou suscetíveis pelo FR foram similarmente classificados pelo IG, mostrando uma estreita relação entre as duas metodologias para a avaliação da resistência. Os dados também indicaram que não houve diferenças quanto à virulência entre as duas populações do nematoide, uma vez que as progênies mostraram similar reação de resistência a M. exigua raça 1 e 2. De acordo com o IG, das 47 plantas-mãe avaliadas, 27 progenies (57,4%) foram classificadas como resistentes a M. exigua raças 1 e 2, com IG variando de 0,0 a 1,4 e 20 progenies (42,6%) foram suscetíveis, com IG variando de 2,6 a 4,4. Esses resultados mostraram que a maioria dos germoplasmas avaliados foi muito promissora em relação ao desenvolvimento de novas cultivares de café Arábica com resistência a M. exigua.

ABSTRACT: To investigate the degree of parasitism of two populations of Meloidogyne exigua, the gall index (GI) and the reproduction factor (RF) of M. exigua races 1 (Est E2) and 2 (Est E1) were analyzed in 47 progenies on F3:4 or F4:5 generation derived from the crossing between Coffea arabica cv. Catuaí Amarelo and Timor Hybrid. C. canephora cv. Apoatã IAC 2258 and C. arabica cv. Catuaí Vermelho IAC 144 were used as resistance and susceptibility checks, respectively. The genotypes that were classified as resistant or susceptible by RF were similarly classified by GI, showing a close relationship between both methodologies. The data also indicated no differences in virulence between the nematode populations, since the progenies showed similar resistance reactions to the M. exigua races 1 and 2. According to GI from the 47 mother plants evaluated, 27 progenies (57.4%) were classified as resistant to M. exigua races 1 and 2, with GI ranging from 0.0 to 1.4 and 20 progenies (42.6%) were susceptible with GI from 2.6 to 4.4. These results showed that most of the evaluated germplasm was very promising in relation to the development of new Arabica coffee cultivars with resistance to M. exigua.

ABSTRACT: Plants of Coffea arabica Icatu IAC 925 germplasm show resistance to Meloidogyne paranaensis under field conditions, but with variable rates of segregation. One mother plant, IAC 3, of Icatu IAC 925 was evaluated under controlled conditions through the reaction of its clones, obtained by somatic embryogenesis. Reproduction of nematodes in clones were compared with an open-pollinated progeny from the same mother plant, C. arabica cultivar Mundo Novo IAC 515-20, susceptible to nematodes, and Clone IAC 1, also susceptible and obtained by somatic embryogenesis. Open-pollinated progeny showed segregation to resistance and was classified as susceptible according to the reproduction factor. The average number of nematodes (eggs and J2) per gram of roots in clones was eight fold lower than that of open-pollinated progeny, and 51 fold lower than Mundo Novo IAC 515-20. Based on Seinhorst model, IAC 3 clone showed a tolerance limit of 7.7 nematodes per cm3 of soil, while in Mundo Novo the tolerance limit was 3.9 nematodes per cm3 of soil. These results revealed that clonal Arabica coffee nematode-resistant trees represent an alternative to the time consuming and expensive process inherent to conventional breeding strategies.

Abstract Brazilian arabica coffee production is based on a set of highly productive cultivars sexually propagated. All of them are susceptible to coffee leaf miner, Leucoptera coffeella, and most of them are also susceptible to coffee leaf rust, Hemileia vastatrix. Aiming to reduce the selection process of cultivars with multiple resistances to both biotic constraints, the Coffea arabica clones 760, 1059, 1064 and 1215 were evaluated under field conditions. The mean yield of four C. arabica clones was not statistically different from the experimental controls; however, the yield of clone 1059 was 21% higher than the control cultivar Obatã IAC 1669-20. Leaf miner resistance level in all the evaluated clones remained the same as the mother plant's. However, the same did not occur for resistance to H. vastatrix, due to the emergence of new pathogen races. In summary, it is potentially feasible the adoption of clone 1059 as a new clonal cultivar resistant to coffee leaf miner.