Selenium application during fruit development can effectively inhibit browning of fresh-cut apples by enhancing antioxidant capacity and suppressing polyphenol oxidase activity.

Browning is a crucial factor affecting the quality of fresh-cut apples. A safe, simple, and effective method to inhibit browning is urgently needed in fresh-cut apple production. We carried out this study to explore the effect mechanism of exogenous selenium (Se) fertilizer on fresh-cut apple browning. During the development of apples, 0.75 kg/plant Se fertilizer was exerted on the 'Fuji' apple tree at the critical stage of the young fruit stage (late May), early fruit expansion stage (late June), and fruit expansion stage (late July), an equal amount of Se-free organic fertilizer was used as control. Polyphenol oxidase (PPO), peroxidase (POD), and phenylalanine ammonia-lyase (PAL) activities, phenolic and malondialdehyde (MDA) content, antioxidant enzymes activity, and DPPH free radical scavenging rate of the apple at different development stages were investigated. The highest Se accumulation efficiency was observed in apple fruit one month after applying Se fertilizer, which was 41.1%. Se-rich apples exhibited a more remarkable ability to resist browning than control after fresh-cut. The anti-browning effect of the fertilization group (M7) was the best, the PPO activity decreased to 0.5 × 103 U kg-1, and the browning index was 28.6. The total Se content (TSC) of 331.4 µg kg-1 DW and organic Se content (OSC) of 292.0 µg kg-1 DW were the highest in the apple samples, reached the classification standard of Se content in Se-rich food. The correlation analysis found that fresh-cut apple browning was closely related to antioxidant capacity and PPO activity. The stronger the antioxidant capacity of fresh-cut apples treated with Se fertilizer, the lower their browning degree. Therefore, exogenous Se can alleviate fresh-cut apples browning by improving antioxidant capacity and reducing PPO activity. Se-rich apples could increase the Se content of the human essential trace element and inhibit the browning of fresh-cut apples, which would become a new, safe and effective way to solve the fresh-cut apples browning.

Complete mitochondrial genome of Phyllonorycter ringoniella (Lepidoptera: Gracillariidae).

The complete mitochondrial genome of Phyllonorycter ringoniella (Matsumura, 1931) is characterized by a circular with 15,729 bp in size, containing 37 encoded genes and a control region. The gene order and nucleotide composition are similar to the known gracillariid mitogenomes. All protein-coding genes (PCGs) initiate with ATN and terminate with TAN, while cox1 starts with CGA, cox1, cox2, nad3, and nad5 terminate with an incomplete codon TA- or T-. All transfer RNA genes (tRNAs) can fold into typical clover-leaf structure, except for trnS1 (AGN), in which dihydrouridine stem is simplified to form a loop structure. The control region is located between 12S rRNA and trnM with relatively strong AT bias. The phylogenetic trees reveal that two subfamilies Oecophyllembiinae and Acrocercopinae were clustered together, and that clade was sister to the subfamily Lithocolletinae. All species of the genus Phyllonorycter grouped into a monophyletic clade and the P. ringoniella was closely related to P. platani.