CYTOKININ OXIDASE/DEHYDROGENASE3 maintains cytokinin homeostasis during root and nodule development in Lotus japonicus

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CYTOKININ OXIDASE/DEHYDROGENASE3 maintains cytokinin homeostasis during root and nodule development in Lotus japonicus. / Reid, Dugald Elgin; Heckmann, Anne Birgitte; Novak, Ondrej; Kelly, Simon; Stougaard, Jens.

In: Plant Physiology, Vol. 170, No. 2, 2016, p. 1060-1074.

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@article{1ec5d96727cd46cb9d01a34982d6daef,
title = "CYTOKININ OXIDASE/DEHYDROGENASE3 maintains cytokinin homeostasis during root and nodule development in Lotus japonicus",
abstract = "Cytokinins are required for symbiotic nodule development in legumes and cytokinin signalling responses occur locally in nodule primordia and in developing nodules. Here we show that the Lotus japonicus Ckx3 cytokinin oxidase/dehydrogenase gene is induced by Nod Factor during the early phase of nodule initiation. At the cellular level, pCkx3::YFP reporter-gene studies revealed that the Ckx3 promoter is active during the first cortical cell divisions of the nodule primordium and in growing nodules. Cytokinin measurements in ckx3 mutants confirmed that CKX3 activity negatively regulates root cytokinin levels. Particularly tZ and DHZ type cytokinins in both inoculated and uninoculated roots were elevated in ckx3 mutants suggesting that these are targets for degradation by the CKX3 cytokinin oxidase/dehydrogenase. The effect of CKX3 on the positive and negative roles of cytokinin in nodule development, infection and regulation was further clarified using ckx3 insertion mutants. Phenotypic analysis indicated that ckx3 mutants have reduced nodulation, infection thread formation and root growth. We also identify a role for cytokinin in regulating nodulation and nitrogen fixation in response to nitrate as ckx3 phenotypes are exaggerated at increased nitrate levels. Together, these findings show that cytokinin accumulation is tightly regulated during nodulation in order to balance the requirement for cell divisions with negative regulatory effects of cytokinin on infection events and root development.",
author = "Reid, {Dugald Elgin} and Heckmann, {Anne Birgitte} and Ondrej Novak and Simon Kelly and Jens Stougaard",
note = "{\textcopyright} 2015 American Society of Plant Biologists. All rights reserved.",
year = "2016",
doi = "10.1104/pp.15.00650",
language = "English",
volume = "170",
pages = "1060--1074",
journal = "Plant Physiology",
issn = "0032-0889",
publisher = "American Society of Plant Biologists",
number = "2",

}

RIS

TY - JOUR

T1 - CYTOKININ OXIDASE/DEHYDROGENASE3 maintains cytokinin homeostasis during root and nodule development in Lotus japonicus

AU - Reid, Dugald Elgin

AU - Heckmann, Anne Birgitte

AU - Novak, Ondrej

AU - Kelly, Simon

AU - Stougaard, Jens

N1 - © 2015 American Society of Plant Biologists. All rights reserved.

PY - 2016

Y1 - 2016

N2 - Cytokinins are required for symbiotic nodule development in legumes and cytokinin signalling responses occur locally in nodule primordia and in developing nodules. Here we show that the Lotus japonicus Ckx3 cytokinin oxidase/dehydrogenase gene is induced by Nod Factor during the early phase of nodule initiation. At the cellular level, pCkx3::YFP reporter-gene studies revealed that the Ckx3 promoter is active during the first cortical cell divisions of the nodule primordium and in growing nodules. Cytokinin measurements in ckx3 mutants confirmed that CKX3 activity negatively regulates root cytokinin levels. Particularly tZ and DHZ type cytokinins in both inoculated and uninoculated roots were elevated in ckx3 mutants suggesting that these are targets for degradation by the CKX3 cytokinin oxidase/dehydrogenase. The effect of CKX3 on the positive and negative roles of cytokinin in nodule development, infection and regulation was further clarified using ckx3 insertion mutants. Phenotypic analysis indicated that ckx3 mutants have reduced nodulation, infection thread formation and root growth. We also identify a role for cytokinin in regulating nodulation and nitrogen fixation in response to nitrate as ckx3 phenotypes are exaggerated at increased nitrate levels. Together, these findings show that cytokinin accumulation is tightly regulated during nodulation in order to balance the requirement for cell divisions with negative regulatory effects of cytokinin on infection events and root development.

AB - Cytokinins are required for symbiotic nodule development in legumes and cytokinin signalling responses occur locally in nodule primordia and in developing nodules. Here we show that the Lotus japonicus Ckx3 cytokinin oxidase/dehydrogenase gene is induced by Nod Factor during the early phase of nodule initiation. At the cellular level, pCkx3::YFP reporter-gene studies revealed that the Ckx3 promoter is active during the first cortical cell divisions of the nodule primordium and in growing nodules. Cytokinin measurements in ckx3 mutants confirmed that CKX3 activity negatively regulates root cytokinin levels. Particularly tZ and DHZ type cytokinins in both inoculated and uninoculated roots were elevated in ckx3 mutants suggesting that these are targets for degradation by the CKX3 cytokinin oxidase/dehydrogenase. The effect of CKX3 on the positive and negative roles of cytokinin in nodule development, infection and regulation was further clarified using ckx3 insertion mutants. Phenotypic analysis indicated that ckx3 mutants have reduced nodulation, infection thread formation and root growth. We also identify a role for cytokinin in regulating nodulation and nitrogen fixation in response to nitrate as ckx3 phenotypes are exaggerated at increased nitrate levels. Together, these findings show that cytokinin accumulation is tightly regulated during nodulation in order to balance the requirement for cell divisions with negative regulatory effects of cytokinin on infection events and root development.

U2 - 10.1104/pp.15.00650

DO - 10.1104/pp.15.00650

M3 - Journal article

C2 - 26644503

VL - 170

SP - 1060

EP - 1074

JO - Plant Physiology

JF - Plant Physiology

SN - 0032-0889

IS - 2

ER -