Duplicated antagonistic EPF peptides optimize grass stomatal initiation

Abstract

Peptide signaling has emerged as a key component of plant growth and development, including stomatal patterning, which is critical for plant productivity and survival. Although exciting progress has been made in understanding EPIDERMAL PATTERNING FACTOR (EPF) signaling in Arabidopsis, the mechanisms by which EPF peptides control different stomatal patterns and morphologies in grasses is poorly understood. Here, by examining expression patterns, overexpression transgenics, and cross-species complementation, the antagonistic stomatal ligands orthologous to Arabidopsis AtEPF2 and AtSTOMAGEN/AtEPFL9 peptides were identified in Triticum aestivum(wheat) and the grass model organism Brachypodium distachyon. Application of bioactive BdEPF2 peptides inhibited stomatal initiation, but not the progression or differentiation of stomatal precursors in Brachypodium. Additionally, the inhibitory roles of these EPF peptides during grass stomatal development were suppressed by the contrasting positive action of the BdSTOMAGEN peptide in a dose-dependent manner. These results not only demonstrate how conserved EPF peptides that control different stomatal patterns exist in nature but also suggest new strategies to improve crop yield through the utilization of plant-derived antagonistic peptides that optimize stomatal density on the plant epidermis.

Paralog editing tunes rice stomatal density to maintain photosynthesis and improve drought tolerance

“…Previous work has suggested the STOMAGEN paralog EPFL10 (LOC_Os08g41360) may function as a weak, positive regulator of stomatal development 28,29 , having arisen from a putative duplication event in the most recent common ancestor of the Poaceae species 27 . We examined evolutionary divergence of STOMAGEN and EPFL10 that may explain such functional differences.The two paralogs have accumulated divergent point mutations.…”

“…Transgenic overexpression of rice STOMAGEN and its duplicate, previously named EPFL9-2, in A. thaliana revealed a shared, though attenuated, function of EPFL9-2 as a positive regulator of stomatal development when ectopically expressed 28 . Ectopic expression of Brachypodium distachyon and Triticum aestivum (wheat) STOMAGEN and STOMAGEN paralogs in A. thaliana resulted in similar stomatal density increases 29 . In contrast, overexpression of negative regulators of stomatal development reduced stomatal density.…”

Regulation of hair cell and stomatal size by a hair-cell specific peroxidase in the grassBrachypodium distachyon

“…Many core players guiding grass stomatal de- velopment were characterized (Abrash et al, 2018;Cartwright et al, 2009;Facette et al, 2015;Humphries et al, 2011;Jangra et al, 2021;Liu et al, 2009;Nunes et al, 2020;Raissig et al, 2017Raissig et al, , 2016Wang et al, 2019;Wu et al, 2019), whereas hair cell formation remains poorly explored (Torii, 2021). Few grass trichome initiation factors such as the transcription factors HAIRY LEAF 6 (HL6) (Fei et al, 2020;Sun et al, 2017)(Angeles-Shim et al, 2012Sun et al, 2017) and SQUAMOSA PROMOTER BINDING PROTEIN-LIKE 10/14/26 (SPL10/14/26) (Kong et al, 2021) , (Lan et al, 2019; were identified in rice and maize, but factors that affect morphogenesis and size remain mostly unknown.…”

“…Yet, the mechanisms that coordinate the formation and growth of stomata and trichomes remain highly unexplored. Many core players guiding grass stomatal development were characterized 2,3,18,[43][44][45][46][47][48][49][50] , whereas grass hair cell formation remains poorly explored 41 . Few grass trichome initiation factors such as the transcription factors HAIRY LEAF 6 (HL6) [51][52][53] and SQUAMOSA PROMOTER BINDING PROTEIN-LIKE 10/14/26 (SPL10/14/26) 5,54,55 were identified in rice and maize, but factors that affect morphogenesis and size remain mostly unknown.…”