EPIP-Evoked Modifications of Redox, Lipid, and Pectin Homeostasis in the Abscission Zone of Lupine Flowers

Abstract

Yellow lupine is a great model for abscission-related research given that excessive flower abortion reduces its yield. It has been previously shown that the EPIP peptide, a fragment of LlIDL (INFLORESCENCE DEFICIENT IN ABSCISSION) amino-acid sequence, is a sufficient molecule to induce flower abortion, however, the question remains: What are the exact changes evoked by this peptide locally in abscission zone (AZ) cells? Therefore, we used EPIP peptide to monitor specific modifications accompanied by early steps of flower abscission directly in the AZ. EPIP stimulates the downstream elements of the pathway—HAESA and MITOGEN-ACTIVATED PROTEIN KINASE6 and induces cellular symptoms indicating AZ activation. The EPIP treatment disrupts redox homeostasis, involving the accumulation of H2O2 and upregulation of the enzymatic antioxidant system including superoxide dismutase, catalase, and ascorbate peroxidase. A weakening of the cell wall structure in response to EPIP is reflected by pectin demethylation, while a changing pattern of fatty acids and acyl lipids composition suggests a modification of lipid metabolism. Notably, the formation of a signaling molecule—phosphatidic acid is induced locally in EPIP-treated AZ. Collectively, all these changes indicate the switching of several metabolic and signaling pathways directly in the AZ in response to EPIP, which inevitably leads to flower abscission.

Transcriptome and targeted hormone metabolome reveal the molecular mechanisms of flower abscission in camellia

“…In the current work, RNA-seq analysis indicated bidirectional changes in the expression of cell wall-related genes, which may be involved in both the continuing abscission process and the growth of undescended organs ( Merelo et al., 2017 ; Wu et al., 2021 ). Pathways associated with cell wall formation, including cell wall biogenesis, galactose and mannose metabolism, aminoglycan, pectin synthesis, and other related genes, exhibited divergent patterns at various phases of CHF and CF ( Wilmowicz et al., 2021 ; Gupta et al., 2021 ). Cell wall production is accompanied by active cell division; several cell wall-related genes may play highly specialized roles in cell wall modification, and some of these gene products may be essential for the optimal function of other genes.…”

A Non-Shedding Fruit Elaeis oleifera Palm Reveals Perturbations to Hormone Signaling, ROS Homeostasis, and Hemicellulose Metabolism

“…ROS production is involved in the abscission of different organs, including Arabidopsis floral organs, lupine flowers, cotton leaves, water-deficit-stress-induced cassava leaves and carbohydrate-stress-induced longan fruit abscission [73][74][75][76][77][78]. During Arabidopsis floral organ abscission, differential ROS distribution characterizes the AZ residuum cells (RECs), which have a higher accumulation of superoxide (O 2 − ) and secession cells (SECs), with a higher accumulation of hydrogen peroxide (H 2 O 2 ).…”

The transcriptional control of LcIDL1–LcHSL2 complex by LcARF5 integrates auxin and ethylene signaling for litchi fruitlet abscission

“…The IDA protein, as well as IDA-like proteins, contains a highly conserved C-terminal EPIP (extended PIP) domain that is crucial for its signaling activity (Butenko et al, 2003(Butenko et al, , 2014Stenvik et al, 2008). The EPIP domain interacts with the extracellular region of the HAE/HSL2 receptor, leading to its autophosphorylation (Wilmowicz et al, 2021). The formation of the IDA-HAE/HSL2 complex triggers a mitogen-activated protein kinase cascade, which regulates the expression of cell wall remodeling enzymes necessary for cell separation in the AZ (Cho et al, 2008).…”