RESUMO As glutationas peroxidases vegetais (GPXs) consistem em peroxidases não-heme tiol vitais na manutenção da homeostase do peróxido de hidrogênio e na regulação das respostas ao estresse ambiental das plantas. Foi efetuada uma análise genômica comparativa da família de genes GPX em Ipomoea trifida e I. triloba, utilizando-se seus respectivos genomas. Foram identificados 6 genes GPX em cada espécie, que estavam localizados de forma desigual em 4 dos 15 cromossomos dos ancestrais mais próximos dos genomas da batata-doce (I. trifida e I. triloba). Apresença de duplicações gênicas e a seleção positiva foram destacadas, sugerindo o significado evolutivo dos genes GPX nessas espécies. Com base na análise filogenética, os genes GPX de I. trifida, I. triloba, Arabidopsis thaliana e Oryza sativa podem ser classificados em quatro grupos (I, II, III e IV). A análise da expressão in silico em diferentes tecidos e estágios de desenvolvimento mostraram padrões de expressão específicos de tecidos, sugerindo papéis especializados para os genes GPX em diferentes órgãos vegetais. No entanto, os genes ItfGPX5 e ItbGPX5 foram altamente expressos na maioria dos tecidos estudados. GPXs (GPXs nãoheme não heme plantas I triloba utilizandose utilizando se espécie 1 batatadoce batata doce (I triloba. . triloba) destacadas espécies filogenética I, II IV. IV IV) entanto ItfGPX ItbGPX estudados

ABSTRACT Plant glutathione peroxidases (GPXs) consist of non-heme thiol peroxidases that are vital in maintaining hydrogen peroxide homeostasis and regulating plant environmental stress responses. A comparative genomic analysis of the GPX gene family in Ipomoea trifida and I. triloba using their respective genomes was performed. Six GPX genes were identified in each species, which were unevenly located in 4 of the 15 chromosomes of the closest ancestors of the sweet potato genomes (I. trifida and I. triloba). The presence of gene duplications and positive selection were highlighted, suggesting the evolutionary significance of the GPX genes in these species. Based on the phylogenetic analysis, the GPX genes of I. trifida, I. triloba, Arabidopsis thaliana and Oryza sativa can be classified into four groups (I, II, III and IV). The in silico expression analysis in different tissues and development stages revealed tissue-specific expression patterns, hinting at specialized roles for the GPX genes in different plant organs. Nonetheless, the ItfGPX5 and ItbGPX5 genes were highly expressed in most the studied tissues. GPXs (GPXs nonheme non heme responses I performed species 1 (I triloba. . triloba) highlighted I, II IV. IV IV) tissuespecific tissue specific patterns organs Nonetheless ItfGPX ItbGPX

Abstract Nitrogen (N) is quantitatively the main nutrient required by coffee plants, with acquisition mainly by the roots and mostly exported to coffee beans. Nitrate (NO3–) and ammonium (NH4+) are the most important inorganic sources for N uptake. Several N transporters encoded by different gene families mediate the uptake of these compounds. They have an important role in source preference for N uptake in the root system. In this study, we performed a genome-wide analysis, including in silico expression and phylogenetic analyses of AMT1, AMT2, NRT1/PTR, and NRT2 transporters in the recently sequenced Coffea canephora genome. We analyzed the expression of six selected transporters in Coffea arabica roots submitted to N deficiency. N source preference was also analyzed in C. arabica using isotopes. C. canephora N transporters follow the patterns observed for most eudicots, where each member of the AMT and NRT families has a particular role in N mobilization, and where some of these are modulated by N deficiency. Despite the prevalence of putative nitrate transporters in the Coffea genome, ammonium was the preferential inorganic N source for N-starved C. arabica roots. This data provides an important basis for fundamental and applied studies to depict molecular mechanisms involved in N uptake in coffee trees.

Increased synthesis of galactinol and raffinose family oligosaccharides (RFOs) has been reported in vegetative tissues in response to a range of abiotic stresses. In this work, we evaluated the transcriptional profile of a Coffea canephora galactinol synthase gene (CcGolS1) in two clones that differed in tolerance to water deficit in order to assess the contribution of this gene to drought tolerance. The expression of CcGolS1 in leaves was differentially regulated by water deficit, depending on the intensity of stress and the genotype. In clone 109A (drought-susceptible), the abundance of CcGolS1 transcripts decreased upon exposure to drought, reaching minimum values during recovery from severe water deficit and stress. In contrast, CcGolS1 gene expression in clone 14 (drought-tolerant) was stimulated by water deficit. Changes in galactinol and RFO content did not correlate with variation in the steady-state transcript level. However, the magnitude of increase in RFO accumulation was higher in the tolerant cultivar, mainly under severe water deficit. The finding that the drought-tolerant coffee clone showed enhanced accumulation of CcGolS1 transcripts and RFOs under water deficit suggests the possibility of using this gene to improve drought tolerance in this important crop.