Fig fruit ripening is regulated by the interaction between ethylene and abscisic acid

Abstract

Fleshy fruit ripening is typically regulated by ethylene in climacteric fruits and abscisic acid (ABA) in non‐climacteric fruits. Common fig (Ficus carica) shows a dual‐ripening mechanism, which is not fully understood. Here, we detected separate peaks of ethylene and ABA in fig fruits at the onset‐ and on‐ripening stages, in conjunction with a sharp rise in glucose and fructose contents. In a newly‐designed split‐fruit system, exogenous ethylene failed to rescue fluridone‐inhibited fruit ripening, whereas exogenous ABA rescued 2‐amino‐ethoxy‐vinyl glycine (AVG)‐inhibited fruit ripening. Transcriptome analysis revealed changes in the expression of genes key to both ABA and ethylene biosynthesis and perception during fig fruit ripening. At the de‐greening stage, downregulation of FcACO2 or FcPYL8 retarded ripening, but downregulation of FcETR1/2 did not; unexpectedly, downregulation of FcAAO3 promoted ripening, but it inhibited ripening only before the de‐greening stage. Furthermore, we detected an increase in ethylene emissions in the FcAAO3‐RNAi ripening fruit and a decrease in ABA levels in the FcACO2‐RNAi unripening fruit. Importantly, FcPYL8 can bind to ABA, suggesting that it functions as an ABA receptor. Our findings support the hypothesis that ethylene regulates the fig fruit ripening in an ABA‐dependent manner. We propose a model for the role of the ABA–ethylene interaction in climacteric/non‐climacteric processes.

Polyphenols in fig: a review on their characterisation, biochemistry during ripening, antioxidant activity and health benefits

“…The transcriptome analysis of figs reported alteration in the expression of genes important to both abscisic acid and ethylene biosynthesis during the ripening process. Qiao et al (2021) documented an enhancement in the ethylene emissions in the Ficus carica abscisic aldehyde oxidase -RNA interfered ripening fruit; and a decrease in abscisic acid levels in the Ficus carica aconitase 2 -RNA interfered unripening fruit.…”

“…Qiao et al . (2021) documented an enhancement in the ethylene emissions in the Ficus carica abscisic aldehyde oxidase – RNA interfered ripening fruit; and a decrease in abscisic acid levels in the Ficus carica aconitase 2 – RNA interfered unripening fruit.…”

Metabolomic and transcriptomic analyses reveal new insights into the role of abscisic acid in modulating mango fruit ripening

“…Dissection of the physiological and molecular mechanism of fruit development and ripening is quite important to service breeding practice and postharvest management. It is commonly believed that climacteric fruit ripening is mainly triggered by elevated ethylene levels, while the ripening of non-climacteric fruits is usually activated by an increase in ABA production with fruit development [ 12 ]. Although mango is considered a climacteric fruit, and application of exogenous ethylene obviously stimulated and hastened the ripening process [ 7 , 39 , 51 , 52 ], endogenous ethylene production often varied greatly in different mango cultivars [ 53 ] or in different years in the same cultivar [ 54 ].…”

“…Although fruit species and types are diverse, fruits are, in general, categorized into two types: climacteric (such as tomato) and non-climacteric fruits (such as grape) depending on whether there is a characteristic burst of respiration during fruit development [ 2 , 3 , 9 – 11 ]. It is commonly believed that climacteric fruit ripening is mainly triggered by elevated ethylene levels during fruit development and ripening, while the ripening of non-climacteric fruits is usually activated by an increase in abscisic acid (ABA) production with fruit development [ 12 ]. The involvement of ethylene in fruit ripening has been well documented, and changes in ethylene accumulation with fruit development greatly impact physiological responses, signal transduction, and gene transcription, triggering the processes of fruit ripening [ 3 , 13 ].…”

“…Increasing evidence has shown that ABA accumulation in climacteric fruits (such as tomato, fig, and peach) participates in the regulation of and affects the processes behind fruit ripening [ 12 , 23 , 24 ]. Specifically, the ABA signal triggers ethylene biosynthesis or interacts with the ethylene signal, clearly affecting the fruit ripening processes in tomato, fig, and banana fruits [ 25 ].…”