RESUMO Os fungos do gênero Pyricularia possuem ampla gama de plantas hospedeiras e são capazes de infectar mais de 50 espécies de gramíneas, causando a doença brusone, com danos às espigas. Espécies da forrageira braquiária (Urochloa spp.) podem ser hospedeiras deste gênero de fungo e podem ser importante fonte de inóculo do patógeno para outras culturas agrícolas afetadas pela brusone, especialmente o trigo. O objetivo deste estudo foi determinar a reação de nove cultivares de Urochloa aos patógenos Pyricularia oryzae linhagem Triticum (PoT1), P. pennisetigena, P. urashimae e P. grisea. Foi avaliado também a virulência de sete raças de PoTl á cultivares de braquiária. Houve variação na patogenicidade e virulência das espécies de Pyricularia e raças de PoTl em diferentes cultivares de braquiária. As cultivares Ipyporã, BRS Tupi e Xaraés foram as mais resistentes às diferentes espécies de patógenos da brusone, e raças de PoTl. Portanto, recomenda-se o cultivo dessas variedades em áreas adjacentes às de trigo ou na integração lavoura-pecuária. 5 gramíneas brusone espigas spp. spp PoT1, PoT1 PoT , (PoT1) P pennisetigena grisea Ipyporã Portanto recomendase recomenda se lavourapecuária. lavourapecuária lavoura pecuária. pecuária lavoura-pecuária (PoT1 (PoT

ABSTRACT Fungi of the genus Pyricularia have a wide range of host plants and are capable of infecting more than 50 species of grasses, causing the blast disease, with damage to the ears. Species of the forage signal grass (Urochloa spp.) can be hosts of this genus of fungus and can be an important source of inoculum of the pathogen for other agricultural crops affected by blast, especially wheat. The objective of this study was to determine the reaction of nine cultivars of Urochloa to the pathogens Pyricularia oryzae Triticum lineage (PoTl), P. pennisetigena, P. urashimae, and P. grisea. The virulence of seven races of PoTl to signal grass cultivars was also evaluated. There was variation in the pathogenicity and virulence of Pyricularia species and PoTl races in different signal grass cultivars. The cultivars Ipyporã, BRS Tupi, and Xaraés were the most resistant to the different blast pathogen species and PoTl races. Therefore, it is recommended to cultivate these varieties in areas adjacent to wheat or in crop-livestock integration. 5 grasses disease ears spp. spp PoTl, , (PoTl) P pennisetigena urashimae grisea evaluated Ipyporã Tupi Therefore croplivestock crop livestock integration (PoTl

The white-thread blight and black rot (WTBR) caused by basidiomycetous fungi of the genus Ceratobasidium is emerging as an important plant disease in Brazil, particularly for crop species in the Ericales such as persimmon (Diospyros kaki) and tea (Camellia sinensis). However, the species identity of the fungal pathogen associated with either of these hosts is still unclear. In this work, we used sequence variation in the internal transcribed spacer regions, including the 5.8S coding region of rDNA (ITS-5.8S rDNA), to determine the phylogenetic placement of the local white-thread-blight-associated populations of Ceratobasidium sp. from persimmon and tea, in relation to Ceratobasidium species already described world-wide. The two sister populations of Ceratobasidium sp. from persimmon and tea in the Brazilian Atlantic Forest agroecosystem most likely represent distinct species within Ceratobasidium and are also distinct from C. noxium, the etiological agent of the first description of white-thread blight disease that was reported on coffee in India. The intraspecific variation for the two Ceratobasidium sp. populations was also analyzed using three mitochondrial genes (ATP6, nad1 and nad2). As reported for other fungi, variation in nuclear and mitochondrial DNA was incongruent. Despite distinct variability in the ITS-rDNA region these two populations shared similar mitochondrial DNA haplotypes.

A series of multilocus sequence-based nuclear DNA markers was developed to infer the phylogeographical history of the Basidiomycetous fungal pathogen Rhizoctonia solani AG-1 IA infecting rice and soybean worldwide. The strategy was based on sequencing of cloned genomic DNA fragments (previously used as RFLP probes) and subsequent screening of fungal isolates to detect single nucleotide polymorphisms (SNPs). Ten primer pairs were designed based on these sequences, which resulted in PCR amplification of 200-320 bp size products and polymorphic sequences in all markers analyzed. By direct sequencing we identified both homokaryon and heterokaryon (i.e. dikaryon) isolates at each marker. Cloning the PCR products effectively estimated the allelic phase from heterokaryotic isolates. Information content varied among markers from 0.5 to 5.9 mutations per 100 bp. Thus, the former RFLP codominant probes were successfully converted into six distinctively variable sequence-based nuclear DNA markers. Rather than discarding low polymorphism loci, the combination of these distinctively variable anonymous nuclear markers would constitute an asset for the unbiased estimate of the phylogeographical parameters such as population sizes and divergent times, providing a more reliable species history that shaped the current population structure of R. solani AG-1 IA.