SAUR17 and SAUR50 Differentially Regulate PP2C-D1 during Apical Hook Development and Cotyledon Opening in Arabidopsis

AbstractThe unique apical hook in dicotyledonous plants protects the shoot apical meristem and cotyledons when seedlings emerge through the soil. Its formation involves differential cell growth under the coordinated control of plant hormones, especially ethylene and auxin. Microtubules are essential players in plant cell growth that are regulated by multiple microtubule-associated proteins (MAPs). However, the role and underlying mechanisms of MAP-microtubule modules in differential cell growth are poorly understood. In this study, we found that the previously uncharacterized Arabidopsis MAP WAVE-DAMPENED2-LIKE4 (WDL4) protein plays a positive role in apical hook opening. WDL4 exhibits a temporal expression pattern during hook development in dark-grown seedlings that is directly regulated by ethylene signaling. WDL4 mutants showed a delayed hook opening phenotype while overexpression of WDL4 resulted in enhanced hook opening. In particular, wdl4-1 mutants exhibited stronger auxin accumulation in the concave side of the apical hook. Furthermore, the regulation of the auxin maxima and trafficking of the auxin efflux carriers PIN-FORMED1 (PIN1) and PIN7 in the hook region is critical for WDL4-mediated hook opening. Together, our study demonstrates that WDL4 positively regulates apical hook opening by modulating auxin distribution, thus unraveling a mechanism for MAP-mediated differential plant cell growth.

Download Full-text

On hormonal regulation of the dynamic apical hook development

New Phytologist ◽

10.1111/nph.15626 ◽

2018 ◽

Vol 222 (3) ◽

pp. 1230-1234 ◽

Cited By ~ 5

Author(s):

Yichuan Wang ◽

Hongwei Guo

Keyword(s):

Hormonal Regulation ◽

Apical Hook

Download Full-text

TMK1-mediated auxin signalling regulates differential growth of the apical hook

Nature ◽

10.1038/s41586-019-1069-7 ◽

2019 ◽

Vol 568 (7751) ◽

pp. 240-243 ◽

Cited By ~ 36

Author(s):

Min Cao ◽

Rong Chen ◽

Pan Li ◽

Yongqiang Yu ◽

Rui Zheng ◽

...

Keyword(s):

Differential Growth ◽

Apical Hook ◽

Auxin Signalling

Download Full-text

FRUITFULL Is a Repressor of Apical Hook Opening in Arabidopsis thaliana

International Journal of Molecular Sciences ◽

10.3390/ijms21176438 ◽

2020 ◽

Vol 21 (17) ◽

pp. 6438

Author(s):

Miriam Führer ◽

Angelika Gaidora ◽

Peter Venhuizen ◽

Jedrzej Dobrogojski ◽

Chloé Béziat ◽

...

Keyword(s):

Arabidopsis Thaliana ◽

In Silico ◽

Target Genes ◽

Growth Promotion ◽

In Silico Analysis ◽

Regulatory Elements ◽

Suitable Model ◽

Differential Growth ◽

Apical Hook ◽

Growth Transitions

Plants adjust their architecture to a constantly changing environment, requiring adaptation of differential growth. Despite their importance, molecular switches, which define growth transitions, are largely unknown. Apical hook development in dark grown Arabidopsis thaliana (A. thaliana) seedlings serves as a suitable model for differential growth transition in plants. Here, we show that the phytohormone auxin counteracts the light-induced growth transition during apical hook opening. We, subsequently, identified genes which are inversely regulated by light and auxin. We used in silico analysis of the regulatory elements in this set of genes and subsequently used natural variation in gene expression to uncover correlations between underlying transcription factors and the in silico predicted target genes. This approach uncovered that MADS box transcription factor AGAMOUS-LIKE 8 (AGL8)/FRUITFULL (FUL) modulates apical hook opening. Our data shows that transient FUL expression represses the expression of growth stimulating genes during early phases of apical hook development and therewith guards the transition to growth promotion for apical hook opening. Here, we propose a role for FUL in setting tissue identity, thereby regulating differential growth during apical hook development.

Download Full-text

Role of myo-inositol during skotomorphogenesis in Arabidopsis

Scientific Reports ◽

10.1038/s41598-020-73677-x ◽

2020 ◽

Vol 10 (1) ◽

Author(s):

Naveen Sharma ◽

Chanderkant Chaudhary ◽

Paramjit Khurana

Keyword(s):

Abiotic Stress ◽

Stress Tolerance ◽

Growth And Development ◽

Inositol Phosphate ◽

Abiotic Stress Tolerance ◽

Hypocotyl Growth ◽

Essential Requirement ◽

Apical Hook ◽

Ethylene Response

Abstract Myo-inositol is a ubiquitous metabolite of plants. It is synthesized by a highly conserved enzyme L-myo-inositol phosphate synthase (MIPS; EC 5.5.1.4). Myo-inositol is well characterized during abiotic stress tolerance but its role during growth and development is unclear. In this study, we demonstrate that the apical hook maintenance and hypocotyl growth depend on myo-inositol. We discovered the myo-inositol role during hook formation and its maintenance via ethylene pathway in Arabidopsis by supplementation assays and qPCR. Our results suggest an essential requirement of myo-inositol for mediating the ethylene response and its interaction with brassinosteroid to regulate the skotomorphogenesis. A model is proposed outlining how MIPS regulates apical hook formation and hypocotyl growth.

Download Full-text

A new genus and ten new species of jumping plant lice (Hemiptera: Triozidae) from Allocasuarina (Casuarinaceae) in Australia

Zootaxa ◽

10.11646/zootaxa.3009.1.1 ◽

2011 ◽

Vol 3009 (1) ◽

pp. 1 ◽

Cited By ~ 15

Author(s):

GARY S. TAYLOR ◽

JOHN T. JENNINGS ◽

MATTHEW F. PURCELL ◽

ANDY D. AUSTIN

Keyword(s):

New Species ◽

Fore Wing ◽

New Genus ◽

Hind Tibia ◽

Antennal Segment ◽

Apical Margin ◽

Apical Hook ◽

Segment 8 ◽

Host Associations

Twelve species of jumping plant lice, Hemiptera: Psylloidea, in two genera are recognised from plants of the genus Allocasuarina (Casuarinaceae) in Australia. Aacanthocnema Tuthill & Taylor comprises two species that are here redescribed, Aa. casuarinae (Froggatt) and Aa. dobsoni (Froggatt), together with four new species, Aa. burckhardti Taylor, Aa. huegelianae Taylor, Aa. luehmannii Taylor, and Aa. torulosae Taylor. A new genus, Acanthocasuarina Taylor, comprises six new species: Ac. acutivalvis Taylor, Ac. campestris Taylor, Ac. diminutae Taylor, Ac. muellerianae Taylor, Ac. tasmanica Taylor, and Ac. verticillatae Taylor. Both genera are characterised by an elongate habitus, short Rs and short, triangular radial and cubital fore wing cells, ventrally produced genal processes beneath angular, overhanging apical margin of vertex, antennae short, and nymphs characteristically elongate, heavily sclerotised and scale-like. Species of Acanthocasuarina have rhinaria on antennal segments 4, 6, 8 and 9, the hind tibia has 1 outer and 2 inner spurs and the female proctiger has a posterior apical hook. In contrast, species of Aacanthocnema lack rhinaria on antennal segment 8 and sclerotised spurs on the hind tibia, and the female lacks a posterior apical hook on the proctiger. Trioza banksiae Froggatt stat. rev. is removed from Aacanthocnema. Keys to genera and species are provided, together with notes on their biology, host associations and biogeography.

Download Full-text

Abscission and dehiscence in the squirting cucumber, Ecballium elaterium. Regulation by ethylene

Canadian Journal of Botany ◽

10.1139/b72-179 ◽

1972 ◽

Vol 50 (7) ◽

pp. 1465-1471 ◽

Cited By ~ 21

Author(s):

Michael B. Jackson ◽

Ielene B. Morrow ◽

Daphne J. Osborne

Keyword(s):

Carbon Dioxide ◽

Ethylene Production ◽

Carbon Dioxide Production ◽

Abscission Zone ◽

Anatomical Features ◽

Ethylene Treatment ◽

Apical Hook ◽

Fruit Abscission ◽

Male Flowers ◽

Regulation Of Growth

When treated with ethylene, mature fruits of the squirting cucumber (Ecballium elaterium (L.) A. Rich) abscind and dehisce prematurely. Abscission of male flowers is also accelerated by ethylene. Visible signs of senescence, a rise in ethylene production, and reduced carbon dioxide production always precede abscission or dehiscence in untreated fruits and flowers. The amounts of diffusible cellulase increase in tissues on both sides of the fruit abscission zone after exposure to ethylene. Anatomical features of this abscission zone are described.The leaves of Ecballium do not abscind although the blade and petiole produce large amounts of ethylene at senescence, nor do they separate when ethylene is supplied. Ethylene treatment of attached fruit peduncles accelerates their rate of elongation in the growing zone below the apical hook. The regulation of growth and abscission in these organs is discussed.

Download Full-text

Sperm morphology of the Rattini – are the interspecific differences due to variation in intensity of intermale sperm competition?

Reproduction Fertility and Development ◽

10.1071/rd17431 ◽

2018 ◽

Vol 30 (11) ◽

pp. 1434 ◽

Cited By ~ 4

Author(s):

Tessa Pahl ◽

Hanna J. McLennan ◽

Yun Wang ◽

Anang S. Achmadi ◽

Kevin C. Rowe ◽

...

Keyword(s):

Sexual Selection ◽

Sperm Competition ◽

Sperm Morphology ◽

Tail Length ◽

Sperm Head ◽

Apical Hook ◽

Interspecific Differences ◽

Murine Rodent ◽

Murine Rodents ◽

Sperm Size

It is widely accepted that in mammals a causal relationship exists between postcopulatory sexual selection and relative testes mass of the species concerned, but how much it determines sperm size and shape is debatable. Here we detailed for the largest murine rodent tribe, the Rattini, the interspecific differences in relative testes mass and sperm form. We found that residual testes mass correlates with sperm head apical hook length as well as its angle, together with tail length, and that within several lineages a few species have evolved highly divergent sperm morphology with a reduced or absent apical hook and shorter tail. Although most species have a relative testes mass of 1–4%, these derived sperm traits invariably co-occur in species with much smaller relative testes mass. We therefore suggest that high levels of intermale sperm competition maintain a sperm head with a long apical hook and long tail, whereas low levels of intermale sperm competition generally result in divergent sperm heads with a short or non-existent apical hook and shorter tail. We thus conclude that sexual selection is a major selective force in driving sperm head form and tail length in this large tribe of murine rodents.

Download Full-text

Differential growth at the apical hook: all roads lead to auxin

Frontiers in Plant Science ◽

10.3389/fpls.2013.00441 ◽

2013 ◽

Vol 4 ◽

Cited By ~ 52

Author(s):

Mohamad Abbas ◽

David Alabadí ◽

Miguel A. Blázquez

Keyword(s):

Differential Growth ◽

Apical Hook

Download Full-text