Light Quality and Sucrose-Regulated Detached Ripening of Strawberry with Possible Involvement of Abscisic Acid and Auxin Signaling

Abstract

The regulation of detached ripening is significant for prolonging fruit shelf life. Although light quality and sucrose affecting strawberry fruit ripening have been widely reported, little information is available about how they co-regulate the strawberry detached ripening process. In this study, different light qualities (red light—RL, blue light—BL, and white light—WL) and 100 mM sucrose were applied to regulate the ripening of initial red fruits detached from the plant. The results showed RL-treated samples (RL + H2O, RL + 100 mM sucrose) had brighter and purer skin color with a higher L*, b*, and C* value, and promoted the ascorbic acid. Almost all light treatments significantly decreased TSS/TA (total soluble solid/titratable acid) and soluble sugar/TA ratio, which is exacerbated by the addition of sucrose. Blue or red light in combination with sucrose notably increased total phenolic content and decreased malondialdehyde (MDA) accumulation. In addition, blue or red light combined with sucrose increased abscisic acid (ABA) content and promoted ABA signaling by inducing ABA-INSENSITIVE 4 (ABI4) expression and inhibiting SUCROSE NONFERMENTING1-RELATED PROTEIN KINASE 2.6 (SnRK2.6) expression. The strawberries exposed to blue and red light significantly improved auxin (IAA) content compared to the control (0 d), whereas the addition of sucrose inhibited IAA accumulation. Moreover, sucrose treatment suppressed the AUXIN/INDOLE-3-ACETIC ACID 11 (AUX/IAA11) and AUXIN RESPONSE FACTOR 6 (ARF6) expression under different light qualities. Overall, these results indicated that RL/BL + 100 mM sucrose might promote the detached ripening of strawberries by regulating abscisic acid and auxin signaling.

Changes in Phytohormones and Transcriptomic Reprogramming in Strawberry Leaves under Different Light Qualities

“…The light quality affects the content of phytohormones in strawberry plants [ 13 ]. In this study, RL2, BL2, and RBL2 decreased the indole-3-acetic acid (IAA) content compared with NL2.…”

“…Phytohormones participate in light response processes. For example, blue and red light treatments significantly increase the content of indole-3-acetic acid (IAA) in fruit, and a treatment comprising red/blue (100 μmol·m −2 ·s −1 ) + 100 mM of sucrose promotes the detached ripening of strawberries by regulating the signalings of abscisic acid (ABA) and IAA [ 13 ]. Light and ABA independently regulate FaMYB10 (an R2R3 MYB transcription factor) [ 14 ] and FaWRKY71 ( WRKY DNA-binding protein 71) [ 15 ] during the ripening of strawberry fruits.…”

Application of γ-aminobutyric acid improves the postharvest marketability of strawberry by maintaining fruit quality and enhancing antioxidant system

“…The external color of strawberries was determined using a CR-400 chromometer (Konica Minolta, Japan) to obtain a* (redness), b* (yellowness) and L* (brightness) values, according to Jiang et al (2023) method. Firmness was evaluated using a WDGY-4 digital fruit sclerometer (Beijing, China) and defined as newton (N).…”

“…After centrifugation, 1 mL of clear solution was diluted 10-fold for further analysis. The measurement of soluble sugar was conducted using the protocol outlined by Jiang et al (2023) . Titratable acidity was measured titrimetrically with 0.1 M sodium hydroxide (NaOH) and expressed as percentage citric acid equivalents.…”

“…Sample powder (0.4 g) was suspended with 2 mL 5 % (w/v) trichloroacetic acid, and then spined at 8000 g for 20 min at 4 °C. The upper phase was pooled and used to measure ascorbic acid (AsA) content according to the method of Jiang et al (2023) . AsA content was read at 534 nm and expressed as g AsA kg −1 FW.…”