Plant homeodomain proteins provide a mechanism for how leaves grow wide

Conklin, Phillip A.; Johnston, Robyn; Conlon, Brianne R; Shimizu, Rena; Scanlon, Michael J.

doi:10.1242/dev.193623

Cited by 16 publications

(29 citation statements)

References 53 publications

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“…These hormones also modulate PD growth and leaf length by controlling the size of the division zone during steady‐state growth (Nelissen et al ., 2012; De Vos et al ., 2020). Auxin, on the contrary, is involved in ML patterning via the regulation of adaxial–abaxial polarity by small regulatory RNAs (Douglas et al ., 2010; Dotto et al ., 2014), delineation of the margins (Johnston et al ., 2015), and promotion of marginal outgrowth by duplicate WOX3 ( WUSCHEL‐RELATED HOMEOBOX3 ) genes NARROWSHEATH1/2 ( NS1/2 ), which are the maize co‐orthologs of PRESSED FLOWER ( PRS ) in Arabidopsis (Matsumoto & Okada, 2001; Nardmann et al ., 2004; Conklin et al ., 2020). While these studies have discovered links between auxin, CK, and GA in axial patterning, a comprehensive understanding of how these plant hormones control ML growth and vein formation remains elusive.…”

Section: Introductionmentioning

confidence: 99%

Hormonal control of medial–lateral growth and vein formation in the maize leaf

Robil

McSteen

2023

New Phytologist

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Summary Parallel veins are characteristic of monocots, including grasses (Poaceae). Therefore, how parallel veins develop as the leaf grows in the medial–lateral (ML) dimension is a key question in grass leaf development. Using fluorescent protein reporters, we mapped auxin, cytokinin (CK), and gibberellic acid (GA) response patterns in maize (Zea mays) leaf primordia. We further defined the roles of these hormones in ML growth and vein formation through combinatorial genetic analyses and measurement of hormone concentrations. We discovered a novel pattern of auxin response in the adaxial protoderm that we hypothesize has important implications for the orderly formation of 3° veins early in leaf development. In addition, we found an auxin transport and response pattern in the margins that correlate with the transition from ML to proximal–distal growth. We present evidence that auxin efflux precedes CK response in procambial strand development. We also determined that GA plays an early role in the shoot apical meristem as well as a later role in the primordium to restrict ML growth. We propose an integrative model whereby auxin regulates ML growth and vein formation in the maize leaf through control of GA and CK.

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Section: Introductionmentioning

confidence: 99%

Hormonal control of medial–lateral growth and vein formation in the maize leaf

Robil

McSteen

2023

New Phytologist

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“…The formation of tube-shaped leaves in maize can be induced by incubation with the auxin inhibitor NPA (Scanlon, 2003) which leads to a failure of sheath margin separation, and this correlates with a high accumulation of ZmPIN1a in this region at the P4 stage of leaf development (Johnston et al, 2015). Recent work has also shown that NS1 is induced by auxin treatment (Conklin et al, 2021). This suggests that ZmIAA28 may be involved in translation of the auxin concentration signal to leaf margin specification and later margin development.…”

Section: Discussionmentioning

confidence: 99%

“…Mediolateral development in the leaf is driven by WOX gene activity (Conklin et al, 2021; Zhang et al, 2020). Our transcriptional analyses highlight wide-spread miss-regulation of WOX gene expression in Oja , with most significant downregulation associated with potential tube leaf formation, and failure of leaf initiation.…”

Section: Discussionmentioning

confidence: 99%

TheHoja loca1Mutant and AUX/IAA Function in Phytomer Development

Richardson

Sluis

Hake

2020

Preprint

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Auxin plays a vital role in plant organ development, influencing organ initiation and patterning across all axes. The diversity in auxin patterning results from changes in the activities and expression of auxin signaling components, including the AUX/IAA repressors. Higher land plants have multigene AUX/IAA families, which leads to functional redundancy and a lack of phenotype in loss of function mutants. Instead, dominant mutations, which prevent AUX/IAA degradation in response to auxin, have highlighted the importance of these proteins in organ development. Here we report a new dominant AUX/IAA mutant in maize, Hoja loca1 (Oja). Oja has a mutation in the degron motif of ZmIAA28 and affects aerial organ initiation and medio-lateral patterning in the leaf. These phenotypes contrast with other maize AUX/IAA mutants that affect the root or inflorescence only. Oja illustrates the role of auxin signaling in the tight coordination of phytomer unit development and provides evidence of species-specific sub-functionalization of the AUX/IAAs.One Line SummaryThe maize AUX/IAA ZmIAA38 is involved in phytomer coordination, aerial organ initiation and mediolateral patterning, and illustrates species specific sub-functionalization of the AUX/IAAs.

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“…A close examination of Streptochaeta may provide insight into how leaf angle is controlled in diverse grasses. Leaf width in maize is controlled particularly by the WOX3 -like homeodomain proteins NARROWSHEATH1 ( NS1 ) and NS2 , which function in cells at the margins of leaves ( Scanlon et al, 1996 ; Conklin et al, 2020 ). Duplication patterns and expression of NS1 and NS2 genes in the Streptochaeta genome could test whether the models developed for maize were present in the earliest of grasses.…”

Section: Discussionmentioning

confidence: 99%

The Streptochaeta Genome and the Evolution of the Grasses

Seetharam

Bélanger

et al. 2021

Front. Plant Sci.

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In this work, we sequenced and annotated the genome of Streptochaeta angustifolia, one of two genera in the grass subfamily Anomochlooideae, a lineage sister to all other grasses. The final assembly size is over 99% of the estimated genome size. We find good collinearity with the rice genome and have captured most of the gene space. Streptochaeta is similar to other grasses in the structure of its fruit (a caryopsis or grain) but has peculiar flowers and inflorescences that are distinct from those in the outgroups and in other grasses. To provide tools for investigations of floral structure, we analyzed two large families of transcription factors, AP2-like and R2R3 MYBs, that are known to control floral and spikelet development in rice and maize among other grasses. Many of these are also regulated by small RNAs. Structure of the gene trees showed that the well documented whole genome duplication at the origin of the grasses (ρ) occurred before the divergence of the Anomochlooideae lineage from the lineage leading to the rest of the grasses (the spikelet clade) and thus that the common ancestor of all grasses probably had two copies of the developmental genes. However, Streptochaeta (and by inference other members of Anomochlooideae) has lost one copy of many genes. The peculiar floral morphology of Streptochaeta may thus have derived from an ancestral plant that was morphologically similar to the spikelet-bearing grasses. We further identify 114 loci producing microRNAs and 89 loci generating phased, secondary siRNAs, classes of small RNAs known to be influential in transcriptional and post-transcriptional regulation of several plant functions.

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Plant homeodomain proteins provide a mechanism for how leaves grow wide

Cited by 16 publications

References 53 publications

Hormonal control of medial–lateral growth and vein formation in the maize leaf

Hormonal control of medial–lateral growth and vein formation in the maize leaf

TheHoja loca1Mutant and AUX/IAA Function in Phytomer Development

The Streptochaeta Genome and the Evolution of the Grasses

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