Rosa hybrida RhERF1 and RhERF4 mediate ethylene‐ and auxin‐regulated petal abscission by influencing pectin degradation. (26th June 2019)

• Record Type: Journal Article
• Authors: Gao, Yuerong; Liu, Yang; Liang, Yue; Lu, Jingyun; Jiang, Chuyan; Fei, Zhangjun; Jiang, Cai‐Zhong; Ma, Chao; Gao, Junping
• Is Part Of: Plant journal. Volume 99:Number 6(2019)
• Page Start: 1159
• Page End: 1171
• Publication Date: 2019-06-26
• Subjects: carbohydrate metabolism -- cell wall -- hormones -- hormone signaling -- plant growth -- regulation of gene expression -- signaling pathways -- transcription factors; Plant molecular biology -- Periodicals; Plant cells and tissues -- Periodicals; Botany -- Periodicals; 580
• DOI: 10.1111/tpj.14412
• Languages: English
• ISSNs: 0960-7412

Abstract

Summary: The timing of plant organ abscission is modulated by the balance of two hormones, ethylene and auxin, while the mechanism of organ shedding depends on the loss of middle lamella pectin in the abscission zone (AZ). However, the mechanisms involved in sensing the balance of auxin and ethylene and that affect pectin degradation during abscission are not well understood. In this study, we identified two members of the APETALA2/ethylene‐responsive factor (AP2/ERF) transcription factor family in rose ( Rosa hybrida ), RhERF1 and RhERF4 which play a role in petal abscission. The expression of RhERF1 and RhERF4 was influenced by ethylene and auxin, respectively. Reduced expression of RhERF1 or RhERF4 was observed to accelerate petal abscission. Global expression analysis and real‐time PCR assays revealed that RhERF1 and RhERF4 modulate the expression of genes encoding pectin‐metabolizing enzymes. A reduction in the abundance of pectin epitopes was detected in the AZs of RhERF1 and RhERF4 ‐silenced plants by immunofluorescence microscopy analysis. In addition, RhERF1 and RhERF4 were shown to bind to the promoter of the pectin‐metabolizing gene β ‐ GALACTOSIDASE 1 ( RhBGLA1 ), and reduced expression of RhBGLA1 delayed petal abscission. We conclude that during petal abscission, RhERF1 and RhERF4 integrate and coordinate ethylene and auxin signals to modulate pectin metabolism, in part by regulating the expression of RhBGLA1 . Significance Statement: This study reports a mechanism for sensing the auxin/ethylene balance associated with modulating petal abscission via degradation of pectin. We found that the expression levels of RhERF1 and RhERF4 are influenced by ethylene and auxin, respectively, and that RhERF1 and RhERF4 act together to modulate pectin degradation in the abscission zone by directly regulating the β‐galactosidase gene RhBGLA1 .