Auxin Regulates Sucrose Transport to Repress Petal Abscission in Rose (Rosa hybrida)

Abstract

Developmental transitions in plants require adequate carbon resources, and organ abscission often occurs due to competition for carbohydrates/assimilates. Physiological studies have indicated that organ abscission may be activated by sucrose deprivation; however, an underlying regulatory mechanism that links sucrose transport to organ shedding has yet to be identified. Here, we report that transport of sucrose and the phytohormone auxin to petals through the phloem of the abscission zone (AZ) decreases during petal abscission in rose (Rosa hybrida), and that auxin regulates sucrose transport into the petals. Expression of the sucrose transporter RhSUC2 decreased in the AZ during rose petal abscission. Similarly, silencing of RhSUC2 reduced the sucrose content in the petals and promotes petal abscission. We established that the auxin signaling protein RhARF7 binds to the promoter of RhSUC2, and that silencing of RhARF7 reduces petal sucrose contents and promotes petal abscission. Overexpression of RhSUC2 in the petal AZ restored accelerated petal abscission caused by RhARF7 silencing. Moreover, treatment of rose petals with auxin and sucrose delayed ethylene-induced abscission, while silencing of RhARF7 and RhSUC2 accelerated ethylene-induced petal abscission. Our results demonstrate that auxin modulates sucrose transport during petal abscission, and that this process is regulated by a RhARF7-RhSUC2 module in the AZ.

Multi-scale comparative transcriptome analysis reveals key genes and metabolic reprogramming processes associated with oil palm fruit abscission

“…carbon and nitrogen compound shortage caused by phloem flux arrest, or/and by internal hormonal factors (ethylene, JA, ABA). A recent report provided a link between metabolism and the mechanisms of auxin and ethylene regulated abscission [118]. The report demonstrated that auxin regulates sucrose transport during rose petal abscission, antagonistically to ethylene induced abscission.…”

Cross-talk between transcriptome, phytohormone and HD-ZIP gene family analysis illuminates the molecular mechanism underlying fruitlet abscission in sweet cherry (Prunus avium L)

“…Usually, the balance between ethylene and auxin plays a crucial role in the shedding process [ 1 ]. Besides, the lack of carbohydrates can also contribute to the abscission of plant organs [ 7 , 15 ]. Consequently, genes that synthesize these phytohormones and signal transduction pathways also play a key role in the plant organ abscission mechanism [ 16 , 17 ].…”

Potato tuber degradation is regulated by carbohydrate metabolism: Results of transcriptomic analysis

“…Organ abscission is crucial for the natural development of plant parts, such as leaves, flowers, and fruits (Aloni et al, 1997 ; Gómez‐Cadenas et al, 2000 ; Reichardt et al, 2020 ; Zhu et al, 2011 ). Many studies have observed that organ abscission is often induced by competition for carbohydrates, reflected in “early flower drop” in many plants (Gómez‐Cadenas et al, 2000 ; Liang et al, 2020 ). Abscission is not always negative: The “June drop” seen in fruit tree cultivars can help apple growers avoid the negative impact of excessive fruit bearing (McFadyen et al, 2011 ).…”