Abstract Asian soybean rust (ASR) is one of the most destructive diseases affecting soybeans. The causative agent of ASR, the fungus Phakopsora pachyrhizi, presents characteristics that make it difficult to study in vitro, limiting our knowledge of plant-pathogen dynamics. Therefore, this work used leaf lesion laser microdissection associated with deep sequencing to determine the pathogen transcriptome during compatible and incompatible interactions with soybean. The 36,350 generated unisequences provided an overview of the main genes and biological pathways that were active in the fungus during the infection cycle. We also identified the most expressed transcripts, including sequences similar to other fungal virulence and signaling proteins. Enriched P. pachyrhizi transcripts in the resistant (PI561356) soybean genotype were related to extracellular matrix organization and metabolic signaling pathways and, among infection structures, in amino acid metabolism and intracellular transport. Unisequences were further grouped into gene families along predicted sequences from 15 other fungi and oomycetes, including rust fungi, allowing the identification of conserved multigenic families, as well as being specific to P. pachyrhizi. The results revealed important biological processes observed in P. pachyrhizi, contributing with information related to fungal biology and, consequently, a better understanding of ASR.

Curtobacterium flaccumfaciens pv. flaccumfaciens (Cff) causes bacterial wilt on beans (Phaseolus vulgaris) and bacterial tan spot on soybeans (Glycine max). Cff was detected on beans in Brazil in 1995. Plants of commercial and experimental fields of soybean with typical symptoms of the disease were collected in the State of Paraná, Brazil, during the 2011/2012 growing season. The causal agent was identified as Cff by isolation from symptomatic leaves on CNS semi-selective medium, artificial inoculation test and re-isolation in soybean and bean, Gram staining test, solubility in KOH, and by PCR. This is the first report of Cff on soybean in Brazil.