Chloroplast ascorbate peroxidases exert an important role in the maintenance of hydrogen peroxide levels in chloroplasts by using ascorbate as the specific electron donor. In this work, we performed a functional study of the stromal APX in rice (OsAPX7) and demonstrated that silencing of OsAPX7 did not impact plant growth, redox state, or photosynthesis parameters. Nevertheless, when subjected to drought stress, silenced plants (APX7i) show a higher capacity to maintain stomata aperture and photosynthesis performance, resulting in a higher tolerance when compared to non-transformed plants. RNA-seq analyses indicate that the silencing of OsAPX7 did not lead to changes in the global expression of genes related to reactive oxygen species metabolism. In addition, the drought-mediated induction of several genes related to the proteasome pathway and the down-regulation of genes related to nitrogen and carotenoid metabolism was impaired in APX7i plants. During drought stress, APX7i showed an up-regulation of genes encoding flavonoid and tyrosine metabolism enzymes and a down-regulation of genes related to phytohormones signal transduction and nicotinate and nicotinamide metabolism. Our results demonstrate that OsAPX7 might be involved in signaling transduction pathways related to drought stress response, contributing to the understanding of the physiological role of chloroplast APX isoforms in rice.
Background and Aims: Cashew (Anacardium occidentale) is a native Brazilian tree, cultivated in various warm climates across the world. The cashew kernels production has been an important economic activity for many tropical countries, providing a variety of food with great nutrition value. The genetic diversity among the early dwarf cultivars used to production is poorly understood, as is the nutritional composition among nuts from those plants. This work aimed to evaluate the physicochemical characteristics of cashew kernels and to study genetic diversity among twelve cultivars to indicate superior genotypes for future breeding programs. Methods: Cashew kernels from twelve cultivars were evaluated for pH, titratable acidity, moisture, ash, lipids and proteins. The genetic variability was assessed using RAPD and ISSR molecular markers. Data from molecular and physicochemical analyses were used to estimate the genetic distances and Mantel test approach was applied to calculate Pearson’s correlation between the data.Key results: A high genetic variability was found among the cultivars. BRS 274 and BRS 275 were the closest genetically, while CCP 09 and BRS 189 were the most distant ones. On the other hand, EMBRAPA 51 and BRS 226 showed cashew kernels with more similar physicochemical characteristics, while BRS 189 and BRS 253 had the more different ones. Moreover, no correlation was found between the physicochemical and molecular results. Cashew kernels had pH close to neutrality, low acidity, considerable moisture content, and high lipid and protein contents. Conclusions: The cashew kernels from the cultivars studied here had low acidity and pH, considerable moisture and ash contents, and high protein and lipid contents. BRS 189, BRS 253, and CCP 1001 showed the best values for proteins, lipids, acidity, and pH. In addition, those cultivars have maximum distance genetic among them, which can be used as parents in future gene combinations in breeding programs.
Genetic parameters and genotypic values of fruits from umbu-cajazeira clones were determined using the restricted maximum likelihood/best linear unbiased prediction (REML/BLUP) method, from the morphological, physicochemical and chemical characterization of fruits. The experiment was composed of six experimental clones, in three randomized complete block designs and three replicates per plot in an unbalanced arrangement in Ipanguaçu/RN, due to non-fructification of some clones of the experiment. Morphological, physicochemical and chemical characterization of 20 fruits of each clone was performed. The variance components for REML and medium components (BLUP), were estimated using the mixed model's method REML/BLUP. The three best clones selected were from Serra do Mel, Açu, and Carnaubais. The method used allowed selection of clones with high soluble solids content and pulp yield based on the genotypic value of clones. Fruit clones from Serra do Mel can be used for pulp processing or fresh consumption. The Açu clone showed a high pulp yield and is recommended pulp processing. Carnaubais, Alto do Rodrigues, and Ipanguaçu generated fruits for fresh consumption.Key words: fresh consumption; genetic variability; mixed models; Spondias sp. Seleção de clones de umbu-cajazeira utilizando REML/BLUP RESUMOOs parâmetros genéticos e os valores genotípicos de clones de umbu-cajazeira foram determinados utilizando o método REML/ BLUP (restricted maximum likelihood/best linear unbiased prediction), a partir da caracterização morfológica, físico-química e química de frutos. O ensaio foi composto por seis clones experimentais, em delineamento blocos ao acaso com três blocos e três repetições por parcela em arranjo desbalanceado em Ipanguaçu/RN, devido a não frutificação de alguns clones do experimento. A caracterização morfológica, físico-química e química de vinte frutos de cada genótipo foi realizada. Os componentes de variância por REML e componentes de médias (BLUP) foram estimados via modelos mistos pelo método REML/BLUP. Os três melhores clones selecionados foram Serra do Mel, Açu e Carnaubais. O método utilizado permitiu a seleção de clones com alto teor de sólidos solúveis e rendimento de polpa, baseado no valor genotípico dos clones. Os frutos do clone Serra do Mel podem ser utilizados para o processamento de polpa e para o consumo in natura. O clone Açu apresentou elevado rendimento de polpa sendo recomendado para o processamento. Carnaubais, Alto do Rodrigues e Ipanguaçu apresentam frutos para o consumo ao natural.Palavras-chave: consumo ao natural; variabilidade genética; modelos mistos; Spondias sp.
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