Continuous Exposure to Ethylene Differentially Affects Senescence in Receptacle and Achene Tissues in Strawberry Fruit

Abstract

Strawberry shelf life is limited, and little is known about the postharvest regulation of senescence in different fruit tissues. Strawberry is classified as a non-climacteric fruit, yet it is known that ethylene affects strawberry ripening. Here the effects of continuous exogenous ethylene (50 µl l −1) were investigated in cold stored strawberry (5°C). The physiological and biochemical responses of ripe strawberry were evaluated across 6 days, together with hormonal profiles of the whole fruit and individual tissues (achenes and receptacle). Continuous exposure to ethylene induced as a first response an accumulation of abscisic acid (ABA) in the receptacle tissue, followed by an increase in CO 2 production. Ethylene also elicited sucrose hydrolysis and malic acid catabolism, with the major effect seen after 4 days of ethylene exposure. Additionally, accumulation of phenolics (epicatechin and chlorogenic acid) were also observed in ethylene treated strawberry. Achenes did not exhibit a response to ethylene, yet catabolism of both ABA and auxins increased by two thirds during air storage. In contrast, ethylene induced ABA accumulation in the receptacle tissue without ABA catabolism being affected. This hormonal disequilibrium in response to ethylene between the two tissues was maintained during storage, and therefore might be the precursor for the following biochemical variations reported during storage.

Metabolic Profile of Strawberry Fruit Ripened on the Plant Following Treatment With an Ethylene Elicitor or Inhibitor

“…(2015) also reported that ethylene treatments increased total sugar content in white as well as green detached strawberry fruit. In addition, Tosseti et al. (2020) reported the propensity of ethylene to elicit an accumulation of reducing sugars, together with a concomitant decline in sucrose in cold stored strawberry.…”

“…Previous studies that used ethylene elicitors or inhibitors have suggested that exogenous ethylene affects some important quality attributes in strawberry fruit, including firmness (Jiang et al, 2001;Villarreal et al, 2008;Villarreal et al, 2009;Villarreal et al, 2016;Elmi et al, 2017), anthocyanin accumulation and phenylalanine ammonia lyase (PAL) activity (Villarreal et al, 2009;Villarreal et al, 2010;Merchante et al, 2013;Sun et al, 2013;Lopes et al, 2015), phenolic compound accumulation (Villarreal et al, 2010;Lopes et al, 2015), organic acids (Merchante et al, 2013;Lopes et al, 2015;Elmi et al, 2017), sugars (Villarreal et al, 2010;Villarreal et al, 2016;Tosetti et al, 2020) and volatile-related genes (Merchante et al, 2013). However, most of these studies have been conducted with immature strawberry fruit following detachment from the plant, which may alter fruit physiology.…”

“…Due to low rates of ethylene production and respiration during ripening, strawberry fruit are classified as nonclimacteric ( Barry and Giovannoni, 2007 ; Bapat et al., 2010 ). However, recent studies have suggested ethylene ( Trainotti et al., 2005 ; Iannetta et al., 2006 ; Bapat et al., 2010 ; Villarreal et al., 2010 ; Merchante et al., 2013 ; Sun et al., 2013 ; Lopes et al., 2015 ) and its interaction with other plant growth regulators such as abscisic acid ( Jia et al., 2011 ; Symons et al., 2012 ; Jia et al., 2013 ; Ayub et al., 2016 ; Jia et al., 2016 ; Tosetti et al., 2020 ) and brassinosteroid ( Ayub et al., 2018b ; Ayub et al., 2018a ) may affect strawberry fruit ripening.…”

Abscisic Acid: Role in Fruit Development and Ripening

“…Similar results were observed in the case of other non-climacteric fruit such as strawberry and pepper. They observed ethylene mediated ABA accumulation in strawberry and activation of acyltransferase gene transcription due to overexpression of ethylene regular FveERF (FvH4_5g04470.1) ( Tosetti et al, 2020 ). In pepper ( Capsicum ), ethylene was shown to regulate fruit color, influencing carotenoid biosynthesis positively.…”

The Physiological and Molecular Mechanism of Abscisic Acid in Regulation of Fleshy Fruit Ripening

“…Although ethylene is well known as a key regulator in climacteric fruit ripening ( Liu et al, 2015 ), this gaseous molecule also participates in non-climacteric fruit ripening through its interaction with ABA ( Li et al, 2020 ; Tosetti et al, 2020 ). In postharvest strawberry fruit, ethylene facilitates ABA accumulation in receptacle tissue but does not affect ABA catabolism ( Tosetti et al, 2020 ). Overexpression of FveERF (FvH4_5g04470.1), an ethylene response regulator, activates both acyltransferase (AAT) gene transcription and ester accumulation during strawberry fruit ripening ( Li et al, 2020 ).…”