Differential Metabolic Rearrangements after Cold Storage Are Correlated with Chilling Injury Resistance of Peach Fruits

Abstract

Reconfiguration of the metabolome is a key component involved in the acclimation to cold in plants; however, few studies have been devoted to the analysis of the overall metabolite changes after cold storage of fruits prior to consumption. Here, metabolite profiling of six peach varieties with differential susceptibility to develop mealiness, a chilling-injury (CI) symptom, was performed. According to metabolic content at harvest; after cold treatment; and after ripening, either following cold treatment or not; peach fruits clustered in distinct groups, depending on harvest-time, cold treatment, and ripening state. Both common and distinct metabolic responses among the six varieties were found; common changes including dramatic galactinol and raffinose rise; GABA, Asp, and Phe increase; and 2-oxo-glutarate and succinate decrease. Raffinose content after long cold treatment quantitatively correlated to the degree of mealiness resistance of the different peach varieties; and thus, raffinose emerges as a candidate biomarker of this CI disorder. Xylose increase after cold treatment was found only in the susceptible genotypes, indicating a particular cell wall reconfiguration of these varieties while being cold-stored. Overall, results indicate that peach fruit differential metabolic rearrangements due to cold treatment, rather than differential metabolic priming before cold, are better related with CI resistance. The plasticity of peach fruit metabolism renders it possible to induce a diverse metabolite array after cold, which is successful, in some genotypes, to avoid CI.

Differential lipidome remodeling during postharvest of peach varieties with different susceptibility to chilling injury

“…Six peach varieties with different agronomic characteristics (Table S1, Monti et al , Bustamante et al ) were selected in the present work: Flordaking (FD), Rojo 2 (R2), Spring Lady (SL), Red Globe (RG), Elegant Lady (EL) and Limón Marelli (LM). Fruits from each variety were collected at commercial maturity and flesh firmness between 40 to 70 N, which allowed the ending of the ripening process to take place after harvest (Monti et al ).…”

“…S1). The cold storage treatment at 0°C for 21 days was selected because it successfully discriminates peach varieties according to their different degrees of resistance/susceptibility to chilling injuries (CI) (Bustamante et al , Genero et al ). After 21 days at 0°C, fruits were stored at 20°C for ripening (CS21 + RS fruits, Fig.…”

“…Firmness and soluble solid content were measured in fruits from all postharvest conditions (H, RS, CS, CS21 and CS21 + RS) and described in Table S2 and Bustamante et al (). The amount of expressible juice measured in RS and CS21 + RS fruits (Table S2) allowed us to classify the varieties in: susceptible (FD and R2) and resistant (EL, LM, RG and SL) to CI as reported in Genero et al () and Bustamante et al (). Other CI symptoms, such as flesh browning or internal reddening, were not detected in the varieties selected and the postharvest conditions applied in the present work.…”

“…In addition, proteomic studies have also identified key proteins involved in the protection to cold or in the development of CI symptoms (Lara et al , Nilo et al , Almeida et al ). Recently, an analysis of primary metabolism using gas chromatography–mass spectrometry (GC–MS) indicated that differential metabolic rearrangements due to cold in different peach varieties are related with CI resistance, while candidate biomarkers of resistant/susceptibility to this disorder were also identified (Bustamante et al ). To date, however, there are no reports using large‐scale lipidomics approaches to investigate the influence of low temperatures on peach fruit lipid composition.…”

“…In the present work, the differential remodeling of the lipidome during the postharvest of peach varieties with contrasting susceptibility to CI was investigated. These varieties have been previously characterized in detail (Bustamante et al , Genero et al , Monti et al ), allowing the question of how variation in chilling tolerance between these fruits is reflected in their lipid composition. In addition, the common changes in the lipidome of the six varieties were also analyzed after storage of fruits at ambient or low temperature, providing information about the general responses to normal ripening and low temperature stress, respectively.…”