Ethylene promotes pectin degradation and fruit softening by negatively regulating PavSPL7 in sweet cherry (Prunus avium)

Abstract

Fruit softening significantly impacts the shelf-life and economic value of fruits. Sweet cherries (Prunus avium L.) are particularly prone to damage during transportation due to softening. While ethylene regulates cell wall degradation and fruit softening in various crops, its role and underlying mechanism in sweet cherry softening remain largely unclear. This study demonstrates that 1-aminocyclopropane-1-carboxylic acid (ACC), a key precursor in the synthesis of ethylene, steadily increases throughout sweet cherry fruit development and ripening, while ethylene treatment reduces fruit firmness. Ethylene treatment negatively regulates the transcriptional level of PavSPL7, a gene encoding a plant-specific SQUAMOSA Promoter Binding Protein-Like 7 (SPL) family protein. Overexpression of PavSPL7 suppresses the transcriptional levels of genes involved in cell wall loosening (the expansin A6 gene PavEXPA6), pectin degradation (the pectin methyl esterase gene PavPMEI2 and the pectate lyase gene PavPL8), and ethylene biosynthesis (the ACC synthase gene PavACS7), thereby inhibiting fruit softening. These results suggest that ethylene and PavSPL7 antagonistically regulate fruit softening in sweet cherry through negative feedback loop. It is thus proposed that ethylene promotes pectin degradation by downregulating PavSPL7 expression, thereby facilitating fruit softening. Our work gains insight into molecular mechanism underlying ethylene-mediated regulation of fruit softening in sweet cherry and provides potential targets for manipulation of fruit development and ripening.

Keywords

Sweet cherry / Fruit softening / Ethylene / Cell wall / Pectin degradation / PavSPL7

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Funding

the National Natural Science Foundation of China(32272686)

the National Key Research and Development Program(2022YFD1200501)

the Construction of Beijing Science and Technology Innovation and Service Capacity in Top Subjects(CEFF–PXM2019_014207_000032)

the 2115 Talent Development Program of China Agricultural University

RIGHTS & PERMISSIONS

The Author(s)