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A current perspective on the role of AGCVIII kinases in PIN-mediated apical hook development.

Willige BC, Chory J - Front Plant Sci (2015)

Bottom Line: As predicted by the Cholodny-Went theory, the cause for differential growth is the unequal distribution of the phytohormone auxin.Their localization and activity are regulated by two subfamilies of AGCVIII protein kinases: the D6 PROTEIN KINASEs as well as PINOID and its two closely related WAG kinases.This mini-review focuses on the regulatory mechanism of these AGCVIII kinases as well as their role in apical hook development of Arabidopsis thaliana.

View Article: PubMed Central - PubMed

Affiliation: Salk Institute for Biological Studies , La Jolla, CA, USA.

ABSTRACT
Despite their sessile lifestyle, seed plants are able to utilize differential growth rates to move their organs in response to their environment. Asymmetrical growth is the cause for the formation and maintenance of the apical hook-a structure of dicotyledonous plants shaped by the bended hypocotyl that eases the penetration through the covering soil. As predicted by the Cholodny-Went theory, the cause for differential growth is the unequal distribution of the phytohormone auxin. The PIN-FORMED proteins transport auxin from cell-to-cell and control the distribution of auxin in the plant. Their localization and activity are regulated by two subfamilies of AGCVIII protein kinases: the D6 PROTEIN KINASEs as well as PINOID and its two closely related WAG kinases. This mini-review focuses on the regulatory mechanism of these AGCVIII kinases as well as their role in apical hook development of Arabidopsis thaliana.

No MeSH data available.


Related in: MedlinePlus

Potential PIN-dependent auxin transport routes for establishing the apical hook’s auxin maximum. Gray arrows represent basipetal auxin transport in the stele, whereas red arrows illustrate the potential auxin routes establishing and maintaining the maximum in the apical hook. (A) Model proposed by Zádníková et al. (2010): Higher PIN abundance in the cortex and epidermis of the convex side of the hook enhances the draining of auxin to establish an auxin gradient between both sides. (B) Differential PIN abundance, activity or localization might lead to a preferential auxin transport from the stele through the endodermis into the outer cell files of the concave side. (C) Independent of the basipetal auxin transport in the stele, auxin might be transported through the epidermis from the cotyledons into the concave side of the apical hook. (D) In addition to the other potential auxin routes, polar transport might trap the hormone in order to maintain a local maximum. cot.: cotyledons, hook: apical hook, hyp.: hypocotyl.
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Figure 2: Potential PIN-dependent auxin transport routes for establishing the apical hook’s auxin maximum. Gray arrows represent basipetal auxin transport in the stele, whereas red arrows illustrate the potential auxin routes establishing and maintaining the maximum in the apical hook. (A) Model proposed by Zádníková et al. (2010): Higher PIN abundance in the cortex and epidermis of the convex side of the hook enhances the draining of auxin to establish an auxin gradient between both sides. (B) Differential PIN abundance, activity or localization might lead to a preferential auxin transport from the stele through the endodermis into the outer cell files of the concave side. (C) Independent of the basipetal auxin transport in the stele, auxin might be transported through the epidermis from the cotyledons into the concave side of the apical hook. (D) In addition to the other potential auxin routes, polar transport might trap the hormone in order to maintain a local maximum. cot.: cotyledons, hook: apical hook, hyp.: hypocotyl.

Mentions: Nevertheless, the following mechanism was proposed based on the observation of higher PIN levels in the epidermis and cortex of the convex side: In the hook, auxin transported in the stele is transferred laterally through the endodermis to the outer cell files. Here, the increased PIN levels on the convex side raise the draining of auxin from the outer side out of the hook and hence establish an auxin gradient between both sides (Zádníková et al., 2010, Figure 2A).


A current perspective on the role of AGCVIII kinases in PIN-mediated apical hook development.

Willige BC, Chory J - Front Plant Sci (2015)

Potential PIN-dependent auxin transport routes for establishing the apical hook’s auxin maximum. Gray arrows represent basipetal auxin transport in the stele, whereas red arrows illustrate the potential auxin routes establishing and maintaining the maximum in the apical hook. (A) Model proposed by Zádníková et al. (2010): Higher PIN abundance in the cortex and epidermis of the convex side of the hook enhances the draining of auxin to establish an auxin gradient between both sides. (B) Differential PIN abundance, activity or localization might lead to a preferential auxin transport from the stele through the endodermis into the outer cell files of the concave side. (C) Independent of the basipetal auxin transport in the stele, auxin might be transported through the epidermis from the cotyledons into the concave side of the apical hook. (D) In addition to the other potential auxin routes, polar transport might trap the hormone in order to maintain a local maximum. cot.: cotyledons, hook: apical hook, hyp.: hypocotyl.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4593951&req=5

Figure 2: Potential PIN-dependent auxin transport routes for establishing the apical hook’s auxin maximum. Gray arrows represent basipetal auxin transport in the stele, whereas red arrows illustrate the potential auxin routes establishing and maintaining the maximum in the apical hook. (A) Model proposed by Zádníková et al. (2010): Higher PIN abundance in the cortex and epidermis of the convex side of the hook enhances the draining of auxin to establish an auxin gradient between both sides. (B) Differential PIN abundance, activity or localization might lead to a preferential auxin transport from the stele through the endodermis into the outer cell files of the concave side. (C) Independent of the basipetal auxin transport in the stele, auxin might be transported through the epidermis from the cotyledons into the concave side of the apical hook. (D) In addition to the other potential auxin routes, polar transport might trap the hormone in order to maintain a local maximum. cot.: cotyledons, hook: apical hook, hyp.: hypocotyl.
Mentions: Nevertheless, the following mechanism was proposed based on the observation of higher PIN levels in the epidermis and cortex of the convex side: In the hook, auxin transported in the stele is transferred laterally through the endodermis to the outer cell files. Here, the increased PIN levels on the convex side raise the draining of auxin from the outer side out of the hook and hence establish an auxin gradient between both sides (Zádníková et al., 2010, Figure 2A).

Bottom Line: As predicted by the Cholodny-Went theory, the cause for differential growth is the unequal distribution of the phytohormone auxin.Their localization and activity are regulated by two subfamilies of AGCVIII protein kinases: the D6 PROTEIN KINASEs as well as PINOID and its two closely related WAG kinases.This mini-review focuses on the regulatory mechanism of these AGCVIII kinases as well as their role in apical hook development of Arabidopsis thaliana.

View Article: PubMed Central - PubMed

Affiliation: Salk Institute for Biological Studies , La Jolla, CA, USA.

ABSTRACT
Despite their sessile lifestyle, seed plants are able to utilize differential growth rates to move their organs in response to their environment. Asymmetrical growth is the cause for the formation and maintenance of the apical hook-a structure of dicotyledonous plants shaped by the bended hypocotyl that eases the penetration through the covering soil. As predicted by the Cholodny-Went theory, the cause for differential growth is the unequal distribution of the phytohormone auxin. The PIN-FORMED proteins transport auxin from cell-to-cell and control the distribution of auxin in the plant. Their localization and activity are regulated by two subfamilies of AGCVIII protein kinases: the D6 PROTEIN KINASEs as well as PINOID and its two closely related WAG kinases. This mini-review focuses on the regulatory mechanism of these AGCVIII kinases as well as their role in apical hook development of Arabidopsis thaliana.

No MeSH data available.


Related in: MedlinePlus