Auxin Signaling-Mediated Apoplastic pH Modification Functions in Petal Conical Cell Shaping

Xie Dang; Binqing Chen; Fenglian Liu; Huibo Ren; Xin Liu; Jie Zhou; Yuan Qin; Deshu Lin

doi:10.1016/j.celrep.2020.02.087

Reactive oxygen species mediate conical cell shaping in Arabidopsis thaliana petals

PLoS Genetics ◽

10.1371/journal.pgen.1007705 ◽

2018 ◽

Vol 14 (10) ◽

pp. e1007705 ◽

Cited By ~ 6

Author(s):

Xie Dang ◽

Peihang Yu ◽

Yajun Li ◽

Yanqiu Yang ◽

Yu Zhang ◽

...

Keyword(s):

Reactive Oxygen Species ◽

Arabidopsis Thaliana ◽

Reactive Oxygen ◽

Oxygen Species ◽

Cell Shaping ◽

Conical Cell

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Auxin steers root cell expansion via apoplastic pH regulation in Arabidopsis thaliana

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1613499114 ◽

2017 ◽

Vol 114 (24) ◽

pp. E4884-E4893 ◽

Cited By ~ 89

Author(s):

Elke Barbez ◽

Kai Dünser ◽

Angelika Gaidora ◽

Thomas Lendl ◽

Wolfgang Busch

Keyword(s):

Arabidopsis Thaliana ◽

Cell Wall ◽

Cell Expansion ◽

Ph Regulation ◽

Root Cell ◽

Auxin Signaling ◽

Acid Growth ◽

Gravitropic Response ◽

Apoplastic Ph ◽

Cellular Resolution

Plant cells are embedded within cell walls, which provide structural integrity, but also spatially constrain cells, and must therefore be modified to allow cellular expansion. The long-standing acid growth theory postulates that auxin triggers apoplast acidification, thereby activating cell wall-loosening enzymes that enable cell expansion in shoots. Interestingly, this model remains heavily debated in roots, because of both the complex role of auxin in plant development as well as technical limitations in investigating apoplastic pH at cellular resolution. Here, we introduce 8-hydroxypyrene-1,3,6-trisulfonic acid trisodium salt (HPTS) as a suitable fluorescent pH indicator for assessing apoplastic pH, and thus acid growth, at a cellular resolution in Arabidopsis thaliana roots. Using HPTS, we demonstrate that cell wall acidification triggers cellular expansion, which is correlated with a preceding increase of auxin signaling. Reduction in auxin levels, perception, or signaling abolishes both the extracellular acidification and cellular expansion. These findings jointly suggest that endogenous auxin controls apoplastic acidification and the onset of cellular elongation in roots. In contrast, an endogenous or exogenous increase in auxin levels induces a transient alkalinization of the extracellular matrix, reducing cellular elongation. The receptor-like kinase FERONIA is required for this physiological process, which affects cellular root expansion during the gravitropic response. These findings pinpoint a complex, presumably concentration-dependent role for auxin in apoplastic pH regulation, steering the rate of root cell expansion and gravitropic response.

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Cortical Microtubule Organization during Petal Morphogenesis in Arabidopsis

International Journal of Molecular Sciences ◽

10.3390/ijms20194913 ◽

2019 ◽

Vol 20 (19) ◽

pp. 4913 ◽

Cited By ~ 1

Author(s):

Yanqiu Yang ◽

Weihong Huang ◽

Endian Wu ◽

Chentao Lin ◽

Binqing Chen ◽

...

Keyword(s):

Cell Expansion ◽

Cortical Microtubule ◽

Experimental System ◽

Confocal Imaging ◽

Cellulose Microfibrils ◽

Microtubule Organization ◽

Abaxial Epidermis ◽

Adaxial Epidermis ◽

Cell Shaping ◽

Conical Cell

Cortical microtubules guide the direction and deposition of cellulose microfibrils to build the cell wall, which in turn influences cell expansion and plant morphogenesis. In the model plant Arabidopsis thaliana (Arabidopsis), petal is a relatively simple organ that contains distinct epidermal cells, such as specialized conical cells in the adaxial epidermis and relatively flat cells with several lobes in the abaxial epidermis. In the past two decades, the Arabidopsis petal has become a model experimental system for studying cell expansion and organ morphogenesis, because petals are dispensable for plant growth and reproduction. Recent advances have expanded the role of microtubule organization in modulating petal anisotropic shape formation and conical cell shaping during petal morphogenesis. Here, we summarize recent studies showing that in Arabidopsis, several genes, such as SPIKE1, Rho of plant (ROP) GTPases, and IPGA1, play critical roles in microtubule organization and cell expansion in the abaxial epidermis during petal morphogenesis. Moreover, we summarize the live-confocal imaging studies of Arabidopsis conical cells in the adaxial epidermis, which have emerged as a new cellular model. We discuss the microtubule organization pattern during conical cell shaping. Finally, we propose future directions regarding the study of petal morphogenesis and conical cell shaping.

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