Nematology, 2007, Vol. 9(6), 853-858 Pathogenicity of two Pratylenchus coffeae populations from Brazil on coffee plants Mario M. I NOMOTO 1,∗ , Roberto K. KUBO 2 , Rosangela A. S ILVA 1 , Claudio M.G. OLIVEIRA 2 , Melissa D. TOMAZINI 1 and Paulo MAZZAFERA 3 1 Escola Superior de Agricultura “Luiz de Queiroz”, Universidade de São Paulo, CP 9, 13418-900 Piracicaba, Brazil 2 Laboratório de Nematologia, Instituto Biológico, CP 70, 13001-970 Campinas, Brazil 3 Departamento de Fisiologia Vegetal, Instituto de Biologia, Universidade Estadual de Campinas, CP 6109, 13083-970 Campinas, Brazil Received: 20 April 2007; revised: 5 July 2007 Accepted for publication: 6 July 2007 Summary – There is limited information on the influence of Pratylenchus coffeae on the growth and development of coffee plants, in spite of the widespread occurrence of this nematode in coffee plantations. In addition, populations of P. coffeae vary in morphological and molecular features, as well as reproductive fitness and pathological potential. The objective of the present study was to compare the pathogenicity of two Brazilian P. coffeae populations, K 5 from Coffea arabica roots and M 2 from Aglaonema sp. roots, in terms of their influence on the plant growth and photosynthesis of Arabian coffee (C. arabica). Five experiments were conducted in controlled conditions, and the results demonstrated that K 5 is pathogenic on coffee, as it can reproduce and causes obvious damage on the plant. Moreover K 5 proved to be very virulent on Arabian coffee, considering its effects on seedling mortality, plant growth and photosynthesis. By contrast, M2 was considered to be of low virulence, or even non-pathogenic, on coffee because it failed to reproduce. Thus, the results indicate that K 5 and M 2 may be distinct species, supporting the hypothesis of previous authors. Keywords – Coffea arabica, diversity, pathogenicity, photosynthesis, plant growth, root-lesion nematode. Three species of root-lesion nematodes are parasitic on coffee (Coffea arabica L. and C. canephora Pierre) in Brazil: Pratylenchus brachyurus (Godfrey) Filipjev & S. Stekhoven, P. coffeae (Zimmermann) Filipjev & S. Stekhoven and P. vulnus Allen & Jensen (Kubo et al., 2004). Although P. coffeae is widespread and a major coffee pest in a number of countries in the Caribbean, Central America, Africa and Asia (Schieber & Grullon, 1969; Campos et al., 1990; Kumar & Samuel, 1990), there are only limited studies of its effects on coffee under controlled conditions. In Costa Rican coffee plantations, Salas and Echandi (1961) related low harvest, leaf wilt, chlorosis and shed- ding to poor root development in adult plants infected with P. coffeae. Similar symptoms were described in Brazilian coffee plantations infested with the same nema- tode (Monteiro & Lordello, 1974). According to Kumar (1982), P. coffeae enters the roots of coffee plants after rupturing the epidermis. During its migration through epi- dermal and cortical cells, P. coffeae breaks down cell walls ∗ Corresponding author, e-mail: mminomot@esalq.usp.br and provokes enlargement of cells, resulting in a slight swelling of the root surface. Host-range variability in P. coffeae has been observed in Central America since 1973 (Edwards & Wehunt, 1973). Currently, P. coffeae is the subject of taxonomic debate because recent studies have shown important mor- phological and molecular differences among its popula- tions (Duncan et al., 1999; Wilcken et al., 2002a, b). Two Brazilian populations of P. coffeae, namely K 5 from Arabian coffee C. arabica cv. Mundo Novo collected in Marília and M 2 from Aglaonema sp. collected in Rio de Janeiro, can be differentiated by molecular and morpho- metric features and by their host-range (Duncan et al., 1999; Silva & Inomoto, 2002). According to Silva and Inomoto (2002), K 5 reproduced very slowly and M 2 failed to reproduce on C. arabica, suggesting that coffee is a poor host for K 5 and a non- host for M 2 . However, P. coffeae has been found causing damage in Brazilian coffee plantations. For example, Kubo et al. (2004) reported that P. coffeae occurred in © Koninklijke Brill NV, Leiden, 2007 853 Also available online - www.brill.nl/nemy