The signalling peptide EPFL9 is a positive regulator of stomatal development

Abstract

Summary• The putative secretory peptides epidermal patterning factor 1 (EPF1) and EPF2 act as negative regulators of stomatal clustering and density early in Arabidopsis leaf development.• Here, we investigated whether the related peptide gene epidermal patterning factor-like 9 (EPFL9), which is coexpressed with EPF1 and stomatal density and distribution 1 (SDD1), also plays a role in controlling stomatal development.• Plants manipulated to constitutively overexpress EPFL9 showed increased stomatal density and clustering, and those manipulated to have reduced EPFL9 expression showed reduced stomatal density with no clustering, confirming that EPFL9 is a regulator of stomatal development. Genetic analysis was consistent with EPFL9 acting independently of EPF1 to control stomatal clustering, independently of EPF2 to regulate stomatal density, and independently of SDD1 to control both stomatal clustering and density.• These findings demonstrate that at least three secretory peptides independently regulate stomatal development. Surprisingly, EPFL9 acts to increase, rather than decrease, stomatal density and clustering. However, in common with EPF1 and EPF2, EPFL9 is unlikely to be a substrate for proteolysis by SDD1.

The NMR structure of stomagen reveals the basis of stomatal density regulation by plant peptide hormones

“…The anti-parallel β-sheet is packed with the amino-terminal region, which contains a one-turn 3 10 -helix (residues 10-13), supported by three disulphide bonds, the locations of which (Cys8-Cys41, Cys13-Cys20, and Cys16-Cys43) were identical to those previously obtained by enzymatic digestion and mass spectrometry (MS) 11 . This stomagen core, consisting of the β-sheet and a one-turn 3 10 -helix, does not correspond to a single continuous stretch in the aminoacid sequence; it is separated into N-and carboxy-terminal regions (residues 8-24 and 39-44). These two regions, corresponding to the core, were found to cover relatively conserved regions in the aminoacid sequence alignment of the family (Fig.…”

“…The functions of the other members remain unclear. Interestingly, it is currently known that stomagen (EPFL9) acts as a positive regulator [10][11][12] . One of the most intriguing questions in this area is how and why peptides from the same family can produce opposite effects on stomatal density.…”

The Plant Peptidome: An Expanding Repertoire of Structural Features and Biological Functions

“…Overexpression of EPF1, EPF2, EPFL4, and EPFL5 inhibits stomatal development when ectopically overexpressed (Hara et al, 2009). In contrast, overexpression of EPFL9 (STOMAGEN) results in increased stomatal density and clustering (Hunt et al, 2010). EPFL9 was recently shown to be involved in the light response of the stomatal pathway (Hronková et al, 2015).…”

Lineage-specific stem cells, signals and asymmetries during stomatal development

“…In contrast to EPF1 and EPF2, STOMAGEN (also known as EPFL9) promotes stomatal differentiation (Hunt et al, 2010;Kondo et al, 2010;Sugano et al, 2010). STOMAGEN overexpression results in increased numbers of stomata that are often clustered and, conversely, its antisense suppression reduces the number of stomata (Sugano et al, 2010).…”