Abstract Bacterial pustule is an important soybean disease caused by Xanthomonas citri pv. glycines, but information about genetic resistance to this pathogen is scarce. This study aimed to investigate soybean genetic resistance to bacterial pustule in the flowering stage through association analysis, characterization of candidate SNP markers, and identification of protein-coding genes potentially regulating defense processes. Therefore, 109 soybean cultivars genotyped with a 6k Illumina platform were assessed for disease severity. A genome-wide analysis revealed a total of 13 SNPs significantly associated. Through protein annotation, we identified three markers located inside the coding regions of uncharacterized protein LOC100779077, histone-lysine N-methyltransferase SUVR4, and ABC-transporter B family member-9. Nucleotide polymorphism on the first two of these markers produces a non-synonymous polymorphism with polarity shift from hydrophobic to polar amino acid. It is convenient to prioritize these three candidate markers for validation procedures with the purpose of using them in marker-assisted soybean breeding programs.

ABSTRACT: The biotrophic fungus Hemileia vastatrix causes coffee leaf rust (CLR), one of the most devastating diseases in Coffea arabica . Coffee, like other plants, has developed effective mechanisms to recognize and respond to infections caused by pathogens. Plant resistance gene analogs (RGAs) have been identified in certain plants as candidates for resistance ( R ) genes or membrane receptors that activate the R genes. The RGAs identified in different plants possess conserved domains that play specific roles in the fight against pathogens. Despite the importance of RGAs, in coffee plants these genes and other molecular mechanisms of disease resistance are still unknown. This study aimed to sequence and characterize candidate genes from coffee plants with the potential for involvement in resistance to H. vastatrix . Sequencing was performed based on a library of bacterial artificial chromosomes (BAC) of the coffee clone ‘Híbrido de Timor’ (HdT) CIFC 832/2 and screened using a functional marker. Two RGAs, HdT_LRR_RLK1 and HdT_LRR_RLK2, containing the motif of leucine-rich repeat-like kinase (LRR-RLK) were identified. Based on the presence or absence of the HdT_LRR_RLK2 RGA in a number of differential coffee clones containing different combinations of the rust resistance gene, these RGAs did not correspond to any resistance gene already characterized (SH1-9). These genes were also analyzed using qPCR and demonstrated a major expression peak at 24 h after inoculation in both the compatible and incompatible interactions between coffee and H. vastatrix . These results are valuable information for breeding programs aimed at developing CLR-resistant cultivars, in addition to enabling a better understanding of the interactions between coffee and H. vastatrix .

Resumo Rickettsia felis é uma bactéria intracelular obrigatória capaz de infectar carrapatos, pulgas, piolhos e outros artrópodes. Essa bactéria é classificada como um membro do Grupo de Transição (TRG). Há evidência de que R. felis está relacionada a alguns organismos eucariotos em um relacionamento mutualístico e obrigatório. No entanto, nenhum relato científico mostra alguma relação entre R. felis e traças da ordem Lepidoptera. O presente trabalho relata a primeira identificação da bactéria R. felis em Phereoeca sp. Para isso, empregou-se um ensaio de reação em cadeia da polimerase (PCR) utilizando-se os genes gltA, ompA e ompB. As sequências nucleotídicas mostraram 100% de identidade com outras sequências de Rickettsia felis. Utilizando-se chaves taxonômicas morfológicas e análise por PCR do gene da citocromo oxidase I (COI) foi feita a identificação em nível de espécie da forma jovem das traças. O nucleotídeo sequenciado mostrou 94,94% de similaridade com a espécie Phereoeca praecox. Entretanto, com o baixo número de sequências depositadas nos bancos de dados, a espécie foi classificada como Phereoeca sp. Os resultados sugerem que R. felis pode se desenvolver em um organismo sem alimentação de sangue (Lepidoptera), assim como tem sido demonstrado para a espécie Liposcelis bostrychophila (Psocoptera). Mais investigações são necessárias para confirmar uma possível associação patogênica ou mutualística com traças.

Abstract Rickettsia felis is an obligate intracellular bacterium capable of infecting ticks, fleas, lice, and other arthropods. This bacterium is classified as a member of the Transitional Group (TRG) Rickettsia. It is known the evidence of R. felis mutualistic and obligatory relationship with some eukaryote organisms. However, there aren’t scientific accounts of R. felis and moths of the order Lepidoptera association. The current work reports the first identification of the bacteria R. felis in Phereoeca sp. For that, a polymerase chain reaction (PCR) assay using gltA, ompA, and ompB genes was used. The nucleotide sequences showed 100% of identity with other Rickettsia felis sequences. The genus-level identification of the moth larvae was performed by morphological taxonomic keys and PCR analysis of the cytochrome oxidase I (COI) gene. The nucleotide sequenced showed 94.94% similarity with the species Phereoeca praecox. However, with the low number of sequences deposited in the databases, the species was classified as Phereoeca sp. The results suggest that R. felis may develop in an organism without blood-feeding behavior (Lepidoptera), as it has been demonstrated for booklice (Psocoptera). Further investigation is necessary in order to confirm pathogenic or mutualistic association with moths.

Tradicionalmente, a propagação de leveduras é feita diretamente dentro das dornas de fermentação nas fábricas de cachaça de alambique. Contudo, estas não dispõem de quaisquer dispositivos que permitam otimizar a propagação, na qual a eficiência da aeração é fator primordial para a predominância do metabolismo respiratório, que permite maximizar a reprodução das células e minimizar a formação de etanol. Neste trabalho, avaliou-se o crescimento de leveduras Saccharomyces cerevisiae em um equipamento dotado de sistema de aeração pelo processo de batelada simples (descontínuo) e pelo processo semicontínuo, utilizando-se um meio complexo ou um meio agroindustrial. O uso do equipamento com aeração permitiu maior conversão de substrato em célula e reduziu o nível de etanol e acidez produzidos. A propagação realizada pelo processo semicontínuo foi mais eficiente do que o de batelada simples. A utilização de um meio agroindustrial suplementado com uma fonte proteica, tal como geralmente é realizado na propagação de leveduras para produção de cachaça de alambique, forneceu maiores aumentos de biomassa e melhores parâmetros de propagação, quando comparado com um meio complexo. Estes resultados contribuirão para o desenvolvimento de um protocolo operacional de propagação de fermento a ser utilizado para produção de cachaça de alambique.

Traditionally, the yeast is propagated directly in the fermentation vats in sugarcane spirit factories. However, they have no devices to optimize the propagation, in which the aeration efficiency is a key factor in the prevalence of the respiratory metabolism to maximize yeast reproduction and minimize the formation of ethanol. This study evaluated the growth of the yeast Saccharomyces cerevisiae in equipment with both simple batch and semi-continuous aeration systems using complex or agro industrial media. The use of aerated equipment allowed for greater substrate conversion to cells and reduced the levels of ethanol and acids produced. The propagation carried out by the semi-continuous process was more efficient than that with the simple batch system. The use of an agro industrial medium supplemented with a protein source, as usually done in the propagation of yeast for the production of sugarcane spirit, provided the greatest increases in biomass and the best parameters for propagation as compared to a complex medium. These results will contribute to the development of an operational protocol for propagation of the yeast to be used in the production of sugarcane spirit.