Abscisic acid- and ethylene-induced abscission of yellow lupine flowers is mediated by jasmonates

The appropriate timing of organ abscission determines plant growth, development, reproductive success, and yield in relation to crop species. Among these, yellow lupine is an example of a crop species that loses many fully developed flowers, which limits the formation of pods with high-protein seeds and affects its economic value. Lupine flower abscission, similarly to the separation of other organs, depends on a complex regulatory network functioning in the cells of the abscission zone (AZ). In the present study, genetic, biochemical, and cellular methods were used to highlight the complexity of the interactions among strong hormonal stimulators of abscission, including abscisic acid (ABA), ethylene, and jasmonates (JAs) precisely in the AZ cells, with all results supporting that the JA-related pathway has an important role in the phytohormonal cross-talk leading to flower abscission in yellow lupine. Based on obtained results, we conclude that ABA and ET have positive influence on JAs biosynthesis and signaling pathway in time-dependent manner. Both phytohormones changes lipoxygenase (LOX) gene expression, affects LOX protein abundance, and JA accumulation in AZ cells. We have also shown that the signaling pathway of JA is highly sensitive to ABA and ET, given the accumulation of COI1 receptor and MYC2 transcription factor in response to these phytohormones. The results presented provide novel information about the JAs-dependent separation of organs and provide insight and details about the phytohormone-related mechanisms of lupine flower abscission.

Automated summary

The appropriate timing of organ abscission plays a crucial role in determining plant growth, development, reproductive success, and yield in crop species such as yellow lupine. This study investigated the complex interactions among hormonal stimulators of abscission, including abscisic acid (ABA), ethylene, and jasmonates (JAs), and their role in yellow lupine flower abscission using genetic, biochemical, and cellular methods. The results showed that the JA-related pathway is important in the phytohormonal cross-talk leading to flower abscission. ABA and ET positively influenced JAs biosynthesis and signaling pathway, affecting LOX gene expression, LOX protein abundance, and JA accumulation in AZ cells. The study also revealed that the signaling pathway of JA is highly sensitive to ABA and ET. These findings provide novel insights into the phytohormone-related mechanisms of lupine flower abscission.