Scientia Agrícola
URI permanente para esta coleçãohttps://thoth.dti.ufv.br/handle/123456789/12094
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Item Clonal Arabica coffee resistant to Meloidogyne paranaensis and damage threshold on plants development(Escola Superior de Agricultura "Luiz de Queiroz", 2019-05) Fatobene, Bárbhara Joana dos Reis; Gonçalves, Wallace; Oliveira, Claudio Marcelo Gonçalves; Guerreiro Filho, OliveiroPlants 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.Item Histopathological characterization of Coffea arabica cultivar IPR 106 resistance to Meloidogyne paranaensis(Escola Superior de Agricultura "Luiz de Queiroz", 2019-09) Shigueoka, Luciana Harumi; Dorigo, Orazília França; Arita, Lucas Yuuki; Fonseca, Inês Cristina de Batista; Silva, Santino Aleandro da; Sera, Gustavo Hiroshi; Machado, Andressa Cristina ZamboniMeloidogyne species are widely distributed in coffee growing areas in Brazil, where M. paranaensis is responsible to significant losses to the crop. One of the main management strategies is the use of resistant cultivars, such as Apoatã rootstock and cultivars IPR 100 and IPR 106. However, the parasitic relationship between coffee and M. paranaensis in culti- vars carrying resistance genes has been poorly understood. The objective of this paper was to characterize the resistance response of Coffea arabica cv. IPR 106 to M. paranaensis. For this, penetration and histopathological studies were carried out using root tissues parasitized by the nematode. ‘IPR 106’ and ‘Mundo Novo’ (susceptible cultivar) seedlings were inoculated with 4,000 eggs of M. paranaensis and, 15 days after inoculation (DAI), roots were stained with fuch- sine to verify the penetration rates of the nematode. Histopathological studies were conducted at 15, 30, 45 and 60 DAI and nematode reproduction was calculated at 120 DAI. ‘IPR 106’ did not avoid completely nematode penetration at 15 DAI, although the number of nematodes was 50 % lower than in Mundo Novo, disregarding the hypothesis of a pre-infectional mechanism of resistance that could prevent nematode penetration completely. However, giant cells and col- lapsed nematodes were observed in ‘IPR 106’ at 30 DAI, suggesting that the resistance mecha- nism to M. paranaensis in ‘IPR 106’ involves a post-infectional response and could be mediated by a hypersensitive reaction.