Systems-Based Approaches to Unravel Networks and Individual Elements Involved in Apple Superficial Scald

Abstract

Superficial scald is a major physiological disorder in apple fruit that is induced by cold storage and is mainly expressed as brown necrotic patches on peel tissue. However, a global view of the gene-protein-metabolite interactome underlying scald prevention/ sensitivity is currently missing. Herein, we have found for the first time that cold storage in an atmosphere enriched with ozone (O 3) induced scald symptoms in 'Granny Smith' apple fruits during subsequent ripening at room temperature. In contrast, treatment with the ethylene perception inhibitor 1-methylcyclopropene (1-MCP) reversed this O 3-induced scald effect. Amino acids, including branched-chain amino acids, were the most strongly induced metabolites in peel tissue of 1-MCP treated fruits. Proteins involved in oxidative stress and protein trafficking were differentially accumulated prior to and during scald development. Genes involved in photosynthesis, flavonoid biosynthesis and ethylene signaling displayed significant alterations in response to 1-MCP and O 3. Analysis of regulatory module networks identified putative transcription factors (TFs) that could be involved in scald. Subsequently, a transcriptional network of the genes-proteinsmetabolites and the connected TFs was constructed. This approach enabled identification of several genes coregulated by TFs, notably encoding glutathione Stransferase (GST) protein(s) with distinct signatures following 1-MCP and O 3 treatments. Overall, this study is an important contribution to future functional studies and breeding programs for this fruit, aiding to the development of improved apple cultivars to superficial scald.

Decoding altitude-activated regulatory mechanisms occurring during apple peel ripening

“…High-throughput molecular biological techniques, such as transcriptomic, proteomic, and metabolomic approaches, have been widely used to explore ripening-related mechanisms in fruits, including apples 4 , 11 , 13 , 14 . Moreover multi-omics analyses of apple peel have recently been conducted in our research group 15 , 16 . However, multi-omics studies of peel ripening in association with altitude changes have not been conducted yet.…”

Unraveling Interactions of the Necrotrophic Fungal Species Botrytis cinerea With 1-Methylcyclopropene or Ozone-Treated Apple Fruit Using Proteomic Analysis

“…Ripening parameters, including firmness, titratable acidity (TA), and total soluble solids, of apple fruits were measured on the harvest day and after 60 days storage period, as previously outlined ( Karagiannis et al, 2020 ). On the harvest day, the ripening status of apple fruits was performed using 30 replicate fruits (10 × 3 fruits in three independent replications).…”

“…Turoni Srl, Forli, Italy) with a 12 mm probe. Soluble solids content (SSC) measurement was performed in juice using a refractometer (Atago PR-1, Atago Co., Ltd., Tokyo, Japan) and TA by acid–base titration of maleic acid ( Karagiannis et al, 2020 ).…”

“…In total, 30 fruits (3 × 10 fruits in each replicate) were utilized for the analysis. Apple protein extraction was performed with 5 g of mesocarp tissue based on a phenol extraction protocol ( Karagiannis et al, 2020 ). Two-dimensional electrophoretic separation followed Minas et al (2016) described procedure using a BIO-RAD system.…”

“…Apple, as a climacteric fruit, is characterized by a burst of respiration and ethylene production during its long storage life, which subsequently lead to a rapid fruit ripening accompanied by an undesirable fruit softening ( Karagiannis et al, 2020 ). The 1-methylcyclopropene (1-MCP), an inhibitor of ethylene action, has been widely used in horticultural crops, particularly in apple fruits, to delay ripening, especially following long-term storage ( Li et al, 2016 ; Minas et al, 2018 ).…”