Transcriptome profiling of cashew apples (Anacardium occidentale) genotypes reveals specific genes linked to firmness and color during pseudofruit development.

KEY MESSAGE: We found 34 and 71 key genes potentially involved in flavonoid biosynthesis and cell wall disassembly, respectively, which could be associated with specific peel coloration and softening of each genotype. Cashew apple (Anacardium occidentale) has a great economic importance worldwide due to its high nutritional value, peculiar flavor and aroma. During ripening, the peduncle develops different peel color and becomes quickly fragile due to its oversoftening, impacting its consumers' acceptance. In view of this, the understanding about its transcriptional dynamics throughout ripening is imperative. In this study, we performed a transcriptome sequencing of two cashew apple genotypes (CCP 76 and BRS 265), presenting different firmness and color peel, in the immature and ripe stages. Comparative transcriptome analysis between immature and ripe cashew apple revealed 4374 and 3266 differentially expressed genes (DEGs) to CCP 76 and BRS 265 genotypes, respectively. These genes included 71 and 34 GDEs involved in the cell wall disassembly and flavonoid biosynthesis, respectively, which could be associated with firmness loss and anthocyanin accumulation during cashew apple development. Then, softer peduncle of CCP 76 could be justified by down-regulated EXP and up-regulation of genes involved in pectin degradation (PG, PL and PAE) and in cell wall biosynthesis. Moreover, genes related to flavonoid biosynthesis (PAL, C4H and CHS) could be associated with early high accumulation of anthocyanin in red-peel peduncle of BRS 265. Finally, expression patterns of the selected genes were tested by real-time quantitative PCR (qRT-PCR), and the qRT-PCR results were consistent with transcriptome data. The information generated in this work will provide insights into transcriptome responses to cashew apple ripening and hence, it will be helpful for cashew breeding programs aimed at developing genotypes with improved quality traits.

Transcriptome analysis of acerola fruit ripening: insights into ascorbate, ethylene, respiration, and softening metabolisms.

KEY MESSAGE: The first transcriptome coupled to metabolite analyses reveals major trends during acerola fruit ripening and shed lights on ascorbate, ethylene signalling, cellular respiration, sugar accumulation, and softening key regulatory genes. Acerola is a fast growing and ripening fruit that exhibits high amounts of ascorbate. During ripening, the fruit experience high respiratory rates leading to ascorbate depletion and a quickly fragile and perishable state. Despite its growing economic importance, understanding of its developmental metabolism remains obscure due to the absence of genomic and transcriptomic data. We performed an acerola transcriptome sequencing that generated over 600 million reads, 40,830 contigs, and provided the annotation of 25,298 unique transcripts. Overall, this study revealed the main metabolic changes that occur in the acerola ripening. This transcriptional profile linked to metabolite measurements, allowed us to focus on ascorbate, ethylene, respiration, sugar, and firmness, the major metabolism indicators for acerola quality. Our results suggest a cooperative role of several genes involved in AsA biosynthesis (PMM, GMP1 and 3, GME1 and 2, GGP1 and 2), translocation (NAT3, 4, 6 and 6-like) and recycling (MDHAR2 and DHAR1) pathways for AsA accumulation in unripe fruits. Moreover, the association of metabolites with transcript profiles provided a comprehensive understanding of ethylene signalling, respiration, sugar accumulation and softening of acerola, shedding light on promising key regulatory genes. Overall, this study provides a foundation for further examination of the functional significance of these genes to improve fruit quality traits.

Antioxidant metabolism during fruit development of different acerola (Malpighia emarginata D.C) clones.

The present research work describes the major changes in the antioxidant properties during development of acerola from five different clones. Ripening improved fruit physicochemical quality parameters; however, total vitamin C and total soluble phenols (TSP) contents declined during development, which resulted in a lower total antioxidant activity (TAA). Despite the decline in TSP, at ripening, the anthocyanin and yellow flavonoid content increased and was mainly constituted of cyanidin 3-rhamnoside and quercetin 3-rhamnoside, respectively. The activities of oxygen-scavenging enzymes also decreased with ripening; furthermore, the reduction in vitamin C was inversely correlated to membrane lipid peroxidation, indicating that acerola ripening is characterized by a progressive oxidative stress. Among the studied clones, II47/1, BRS 237, and BRS 236 presented outstanding results for vitamin C, phenols, and antioxidant enzyme activity. If antioxidants were to be used in the food supplement industry, immature green would be the most suitable harvest stage; for the consumer's market, fruit should be eaten ripe.

Aumento da vida útil pós colheita de pedúnculos de cajueiro anão precoce pela redução da temperatura de armazenamento / Increasing shelf life of early dwarf cashew tree peduncle through reduction of storage temperature

Conduziu-se este estudo, realizado no Laboratório de Fisiologia e Tecnologia Pós-Colheita da Embrapa Agroindústria Tropical em Fortaleza (CE), com o objetivo de aumentar o tempo de conservação pós-colheita de pedúnculos dos clones CCP 76 e END 183 de cajueiro anão precoce por meio da redução da temperatura de armazenamento. Foi adotado um fatorial em delineamento inteiramente casualizado, cujos fatores foram os clones e o tempo de armazenamento (0, 5, 10, 15, 20, 25 e 30 dias), avaliados em três repetições. Os frutos, colhidos manualmente, no início da manhã, no Município de Beberibe, Ceará, foram acondicionados em caixas plásticas ainda no campo e transportados para o laboratório onde, acondicionados em bandejas de isopor, foram armazenados a 3,4 ± 0,6ºC e umidade relativa de 85 ± 11 por cento, sob atmosfera modificada. Os parâmetros avaliados foram perda de massa, aparência, cor da película, firmeza da polpa, sólidos solúveis totais, pH, acidez total titulável, SST/ATT, ácido ascórbico, açúcares solúveis totais, antocianinas totais e fenólicos. Os resultados mostraram que os pedúnculos do clone CCP 76 têm vida útil pós-colheita de 18 dias, enquanto o END 183, de 28 dias, ambos com reduzida perda de massa, firmeza e antocianinas totais.

This work aimed to increase, through the reduction storage temperature, the post-harvest conservation time of the early dwarf cashew tree peduncle of clones CCP 76 and END 183. It was carried out in the Postharvest Physiology and Technology Laboratory of the Embrapa Agroindústria Tropical in Fortaleza (State of Ceará, Brazil) using a factorial scheme in a randomized design with three replications of the factors (clones and storage duration: 0, 5, 10, 15, 20, 25 and 30 days). The fruits evaluated were manually harvested in a farm located in the Municipality of Beberibe, State of Ceará, transported in plastic containers to the Laboratory and stored in extruded polystyrene trays at the temperature of 3,4 ± 0,6ºC and relative humidity 85 ± 11 percent under modified atmosphere. The parameters evaluated were weight loss; appearance; peel color; pulp firmness; total soluble solids (TSS); pH; total titratable acidity (TTA); TSS/TTA ratio; ascorbic acid; total soluble sugars; anthocyanins and phenolics. The analyses showed that the shelf life of the CCP 76 peduncle clone is 18 days while that of the END 183 clone is of 28 days, both with slight loss of mass, firmness and total anthocyanins.