title: Nitric oxide-cytokinin interplay influences selenite sensitivity in Arabidopsis.
abstract: Selenite oppositely modifies cytokinin and nitric oxide metabolism in Arabidopsis organs. A mutually negative interplay between the molecules exists in selenite-exposed roots; and their overproduction causes selenite insensitivity. Selenium-induced phytotoxicity is accompanied by developmental alterations such as primary root (PR) shortening. Growth changes are provoked by the modulation of hormone status and signalling. Cytokinin (CK) cooperates with the nitric oxide (NO) in many aspects of plant development; however, their interaction under abiotic stress has not been examined. Selenite inhibited the growth of Arabidopsis seedlings and reduced root meristem size through cell division arrest. The CK-dependent pARR5::GUS activity revealed the intensification of CK signalling in the PR tip, which may be partly responsible for the root meristem shortening. The selenite-induced alterations in the in situ expressions of cytokinin oxidases (AtCKX4::GUS, AtCKX5::GUS) are associated with selenite-triggered changes of CK signalling. In wild-type (WT) and NO-deficient nia1nia2 root, selenite led to the diminution of NO content, but CK overproducer ipt-161 and -deficient 35S:CKX2 roots did not show NO decrease. Exogenous NO (S-nitroso-N-acetyl-DL-penicillamine, SNAP) reduced the pARR5::GFP and pTCS::GFP expressions. Roots of the 35S:CKX and cyr1 plants suffered more severe selenite-triggered viability loss than the WT, while in ipt-161 and gsnor1-3 no obvious viability decrease was observed. Exogenous NO ameliorated viability loss, but benzyladenine intensified it. Based on the results, selenite impacts development by oppositely modifying CK signalling and NO level. In the root system, CK signalling intensifies which possibly contributes to the nitrate reductase-independent NO diminution. A mutually negative CK-NO interplay exists in selenite-exposed roots; however, overproduction of both molecules worsens selenite sensing. Hereby, we suggest novel regulatory interplay and role for NO and CK in abiotic stress signalling.
authors.affiliation: Department of Plant Physiology, Umeå Plant Science Centre, Umeå University, Umeå, Sweden.
authors.forename: Nóra
authors.initials: N
authors.lastname: Lehotai
authors.affiliation: Department of Plant Biology, Faculty of Science and Informatics, University of Szeged, Közép fasor 52, 6726, Szeged, Hungary.
authors.forename: Gábor
authors.initials: G
authors.lastname: Feigl
authors.affiliation: Department of Plant Biology, Faculty of Science and Informatics, University of Szeged, Közép fasor 52, 6726, Szeged, Hungary.
authors.forename: Ágnes
authors.initials: Á
authors.lastname: Koós
authors.affiliation: Department of Plant Biology, Faculty of Science and Informatics, University of Szeged, Közép fasor 52, 6726, Szeged, Hungary.
authors.forename: Árpád
authors.initials: Á
authors.lastname: Molnár
authors.affiliation: Department of Plant Biology, Faculty of Science and Informatics, University of Szeged, Közép fasor 52, 6726, Szeged, Hungary.
authors.forename: Attila
authors.initials: A
authors.lastname: Ördög
authors.affiliation: Department of Plant Biology, Faculty of Science and Informatics, University of Szeged, Közép fasor 52, 6726, Szeged, Hungary.
authors.forename: Andrea
authors.initials: A
authors.lastname: Pető
authors.affiliation: Department of Plant Biology, Faculty of Science and Informatics, University of Szeged, Közép fasor 52, 6726, Szeged, Hungary.
authors.forename: László
authors.initials: L
authors.lastname: Erdei
authors.affiliation: Department of Plant Biology, Faculty of Science and Informatics, University of Szeged, Közép fasor 52, 6726, Szeged, Hungary. kolzsu@bio.u-szeged.hu.
authors.forename: Zsuzsanna
authors.identifier: http://orcid.org/0000-0002-7819-4672
authors.initials: Z
authors.lastname: Kolbert
mesh_terms: D017360:Arabidopsis / Q000187:drug effects / Q000502:physiology*; D003583:Cytokinins / Q000378:metabolism*; D005966:Glucuronidase / Q000378:metabolism; D018519:Meristem / Q000033:anatomy & histology / Q000187:drug effects; D009569:Nitric Oxide / Q000378:metabolism*; D009929:Organ Size / Q000187:drug effects; D018517:Plant Roots / Q000187:drug effects / Q000378:metabolism; D018520:Plant Shoots / Q000187:drug effects / Q000378:metabolism; D036226:Seedlings / Q000187:drug effects / Q000254:growth & development; D020887:Selenious Acid / Q000494:pharmacology*; D012643:Selenium / Q000378:metabolism; D013312:Stress, Physiological / Q000187:drug effects; D013455:Sulfur / Q000378:metabolism
chemical_list: D003583:Cytokinins; D009569:Nitric Oxide; D013455:Sulfur; D005966:Glucuronidase; D020887:Selenious Acid; D012643:Selenium
keywords: Cytokinin; Nitric oxide; Root growth; Selenite