Abscisic acid-responsive transcription factors PavDof2/6/15 mediate fruit softening in sweet cherry

Abstract

Softening is a key step during fruit ripening that is modulated by the interplay between multiple phytohormones. The antagonistic action of abscisic acid (ABA) and auxin determines the rate of fruit ripening and softening. However, the transcription factors that integrate ABA and auxin signals to regulate fruit softening remain to be determined. In this study, we identified several DNA-binding with One Finger (Dof) transcription factors essential for ABA-promoted fruit softening, based on transcriptome analysis of two sweet cherry (Prunus avium L.) varieties with different fruit firmness. We show that PavDof6 directly binds to the promoters of genes encoding cell wall–modifying enzymes to activate their transcription, while PavDof2/15 directly repress their transcription. Transient overexpression of PavDof6 and PavDof2/15 in sweet cherry fruits resulted in precocious and delayed softening, respectively. In addition, we show that the auxin response factor PavARF8, the expression of whose encoding gene is repressed by ABA, activates PavDof2/15 transcription. Furthermore, PavDof2/6/15 and PavARF8 directly bind to the 9-cis-epoxycarotenoid dioxygenase 1 (PavNCED1) promoter and regulate its expression, forming a feedback mechanism for ABA-mediated fruit softening. These findings unveil the physiological framework of fruit softening and establish a direct functional link between the ABA-PavARF8-PavDofs module and cell wall–modifying genes in mediating fruit softening.

Identification and characterization of Dof genes in Cerasus humilis

“…In tomato ( Solanum lycopersicum ), RNA interference experiment showed the expression of SIDof1 is inhibited during fruit ripening, thus delaying the synthesis of lycopene and the process of fruit ripening ( Wang et al., 2021 ). In cherries, in the presence abscisic acid (ABA), PavDof6 directly binds to the promoter encoding the cell wall modification enzyme gene, while PavDof2/15 plays the opposite role, confirming that some members of the PavDof gene family are involved in early maturation and delayed softening of the fruit ( Zhai et al., 2022 ). Transcriptome analysis of kiwifruit showed that Dof genes play a key role in flower and fruit development ( Brian et al., 2021 ).…”

“…In Arabidopsis , VDof1 and VDof2 regulate vascular cell differentiation throughout the life cycle of a plant by targeting different genes at different developmental stages; VDof proteins negatively regulate vein formation at the seedling stage and target lignin biosynthesis at the reproductive stage ( Ramachandran et al., 2020 ). Previous studies have shown that members of the Dof gene family play a very important role in regulating fruit ripening time and delaying fruit softening in small berries such as cherry( Zhai et al., 2022 ), and kiwifruit ( Brian et al., 2021 ). The fruit of C. humilis is also characterized by hard flesh, and therefore is resistant to storage and transportation, which reduces the impact on fruit quality.…”

Banana MabHLH28 positively regulates the expression of softening-related genes to mediate fruit ripening independently or via cooperating with MaWRKY49/111

“…To date, characterization of transcriptional regulators of these softening-related genes is a focused issue in postharvest biology, for the reason that manipulating the expression of distinct upstream regulator using genetic engineering strategy may have potential for prolonging the storage time of the fruit, as is in the case of SlLOB1 in tomato [ 44 ]. Numerous TFs have been identified in fruit softening regulation through targeting the promoters of softening-related genes in various fruits, such as CpERF9 in papaya [ 45 ], SlBES1 in tomato [ 46 ], DkBZR1/2 in kiwifruit [ 47 ], PpERF/ABR1 in peach [ 48 ], FvMYB79 in strawberry [ 49 ], and PavDof2/6/15 in sweet cherry [ 50 ].…”

A 5.2‐kb insertion in the coding sequence of PavSCPL, a serine carboxypeptidase‐like enhances fruit firmness in Prunus avium

“…The trees were planted at a density of 2.5 m 9 1.0 m. In total, 204 surviving F 1 individuals were selected for investigation of fruit firmness at the mature fruit stage from 2016 to 2019. The fruit firmness of two parents ('Rainier' and 'Summit'), three extra-hard-flesh fruit individuals (EH 1, EH 2 and EH 3), three hard-flesh fruit individuals (H 1, H 2 and H 3) and three soft-flesh fruit individuals (S 1, S 2 and S 3) from the F 1 population was assessed at the yellow-white, full red or full colouring (blush type) and dark red or orange-red (blush type) stage from 2016 to 2019 (Garc ıa-G omez et al, 2020(Garc ıa-G omez et al, , 2021Zhai et al, 2022). In addition, 118 sweet cherry accessions were used as a natural segregating population for marker validation (Table S7), which were maintained and grown in the cherry germplasm resource platform of the National Horticultural Germplasm Repository, ZFRI, CAAS, located in Zhengzhou, Henan, China.…”