The facultative biotrophic basidiomycete Sporisorium scitamineum causes smut disease in sugarcane. This study applied an assay to identify S. scitamineum candidate effectors (CEs) with plant immunity suppression activities by delivering them into Nicotiana benthamiana cells via the type-three secretion system of Pseudomonas fluorescens EtHAn. Six CEs were individually cloned into the pEDV6 vector and expressed by P. fluorescens EtHAn for translocation into the plant cells. Three CEs (g1052, g3890, and g5159) could suppress pattern-triggered immunity (PTI) responses with high reproducibility in different co-infiltration experiments with Pseudomo-nas syringae pv. tomato DC3000. In addition, three CEs (g1052, g4549, and g5159) were also found to be AvrB-induced suppressors of effector-triggered immunity (ETI), demonstrating for the first time that S. scitamineum can defeat both PTI and ETI responses. A transcriptomic analy-sis at different stages of infection by the smut fungus of three sugarcane cultivars with con-trasting responses to the pathogen revealed that suppressors g1052, g3890, g4549, and g5159 were induced at the early stage of infection. By contrast, the two CEs (g2666 and g6610) that did not exhibit suppression activities expressed only at the late stage of infection. Moreover, ge-nomic structures of the CEs and searches for orthologs in other smut species suggested duplica-tion events and further divergence in CEs evolution of S. scitamineum. Thus, the transient assay applied here demonstrated the potential of pEDV6 and P. fluorescens EtHAn as biological tools for identifying plant immune suppressors from S. scitamineum.

In July 2020, during a survey carried out in a small farm located in Laranjal Paulista, state of São Paulo (Brazil), more than 20 white pitahaya plants [Hylocereus undatus (Haw.) Britton and Rose (syn. Selenicereus undatus (Haw.) D.R. Hunt] were found with stunting symptoms and showing chlorotic-yellowish stems, some of them already decaying. Roots exhibited numerous galls, indicating Meloidogyne sp. infection. Nematodes were recovered from 200 cm³ and 7 g of roots: 1.7 Meloidogyne juveniles (J2) per cm³ of soil and 954 eggs + J2 per g of roots were found. The perineal pattern of 10 females pointed to M. incognita. Additionally, esterase phenotype was obtained through isozyme electrophoresis, using another 10 females, which identified M. incognita. To our knowledge, this is the first report of M. incognita infesting pitahaya plants (Hylocereus spp.) and, based on our results, M. incognita could be a potential threat to the crop.

Primeiramente a Deus, pela força e oportunidades que me fazem crescer a cada dia. À minha mãe Maria, ao meu irmão Mário e a minha avó Cecilia, por estarem sempre presentes e serem o meu apoio. À minha irmã Erika, por toda ajuda, conselho, amizade e companheirismo demonstrados ao longo de todos esses anos. Ao meu orientador Profº. Mário Massayuki Inomoto, por todos os ensinamentos e apoio. À minha amiga Lillian Bibiano, pelas conversas, conselhos e ajuda durante o atual projeto. Aos meus amigos Pedro Confort, Victor Moura e Ísis Tikami, pelo apoio e troca de experiências. Aos colegas do laboratório de Nematologia da ESALQ/USP Joaquim Dias, Mariana Mailkut, Amanda Borjatto, João Zinsly e Thainá dos Santos pelo apoio durante todo projeto. À Sakata Seed ® Sudamerica, pela concessão das sementes. À Ballagro ® Agro Tecnologia Ltda e Stoller ® do Brasil Ltda, pela doação dos produtos biológicos usados no presente trabalho. À Escola Superior de Agricultura "Luiz de Queiroz", por todas as oportunidades durante a graduação e agora na pós-graduação.