FERONIA Is a Key Modulator of Brassinosteroid and Ethylene Responsiveness in Arabidopsis Hypocotyls

Abstract

Ethylene signaling is a complex pathway that has been intensively analyzed partly due to its importance to the manifestation of horticultural phenomena, including fruit ripening and tissue senescence. In order to further our understanding of how this pathway is regulated, a screen for Arabidopsis mutants with increased ethylene response was conducted. From this, a mutant was identified as having a dark-grown hypocotyl that is indistinguishable from Col-0 wt in the presence of the ethylene perception inhibitor AgNO₃, yet has extreme responsiveness to even low levels of ethylene. Map-based cloning of the mutation revealed a T-DNA insertion in the coding sequence of the receptor-like kinase FERONIA, which is required for normal pollen tube reception and cell elongation in a currently unknown capacity. In contrast to a previous report, analysis of our feronia knockout mutant shows it also has altered responsiveness to brassinosteroids, with etiolated fer-2 seedlings being partially brassinosteroid insensitive with regard to promotion of hypocotyl elongation. Our results indicate that FERONIA-dependent brassinosteroid response serves to antagonize the effect of ethylene on hypocotyl growth of etiolated seedlings, with loss of proper brassinosteroid signaling disrupting this balance and leading to a greater impact of ethylene on hypocotyl shortening.

Hypocotyl Directional Growth in Arabidopsis: A Complex Trait

“…biosynthesis and response (Deslauriers and Larsen, 2010). In contrast to these findings, BR randomizes hypocotyl growth by antagonizing ethylene signaling at low as well as high concentrations.…”

“…For example, BR-induced hook formation depends on ethylene biosynthesis (De Grauwe et al, 2005). BR antagonizes the negative effects of ethylene on hypocotyl growth at a low level but, at higher levels, inhibits hypocotyl elongation through an increase in both ethylene biosynthesis and response (Deslauriers and Larsen, 2010). The ethylene receptor mutant ethylene resistant1-1 (etr1-1) and the signaling mutant ethylene insensitive2 (ein2-1) exhibited a high response, suggesting an antagonistic role in the ethylene signal transduction pathway.…”

FERONIA receptor kinase pathway suppresses abscisic acid signaling in Arabidopsis by activating ABI2 phosphatase

“…The FER gene was first identified as a regulator in the male-female interaction during pollen tube reception (13)(14)(15). FER was later shown to function in several other growth regulatory pathways, including root hair elongation regulated by auxin and cell growth induced by other hormones (10,(16)(17)(18).…”

Receptor-like cytoplasmic kinase MARIS functions downstream of Cr RLK1L-dependent signaling during tip growth

“…7-9). FER, the most thoroughly studied member of this subfamily, controls many developmental processes, such as intercellular communication during fertilization (10)(11)(12), cell elongation (13), calcium and hormone signaling (10,14,15), mechanosensing (16), plant Significance Plant cells constantly survey their environment to fine-tune their internal processes. Plant receptor-like kinases (RLKs) of the Catharanthus roseus RLK1-like (CrRLK1L) subfamily have been implicated in many signaling processes, including the coordination of the intracellular growth machinery with the performance of the extracellular matrix, i.e.…”