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AXR1 promotes the Arabidopsis cytokinin response by facilitating ARR5 proteolysis
Author(s) -
Li Yan,
Kurepa Jasmina,
Smalle Jan
Publication year - 2013
Publication title -
the plant journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.058
H-Index - 269
eISSN - 1365-313X
pISSN - 0960-7412
DOI - 10.1111/tpj.12098
Subject(s) - proteolysis , arabidopsis , cytokinin , biology , chemistry , biochemistry , gene , auxin , mutant , enzyme
Summary The plant hormone cytokinin plays essential roles in many aspects of growth and development. The cytokinin signal is transmitted by a multi‐step phosphorelay to the members of two functionally antagonistic classes of Arabidopsis response regulators ( ARR s): type B ARR s (response activators) and type A ARR s (negative‐feedback regulators). Previous studies have shown that mutations in AXR 1 , encoding a subunit of the E1 enzyme in the RUB (related to ubiquitin) modification pathway, lead to decreased cytokinin sensitivity. Here we show that the cytokinin resistance of axr1 seedlings is suppressed by loss of function of the type A ARR family member ARR 5 . Based on the established role of the RUB pathway in ubiquitin‐dependent proteolysis, these data suggest that AXR 1 promotes the cytokinin response by facilitating type A ARR degradation. Indeed, both genetic ( axr1 mutants) and chemical ( MLN 4924) suppression of RUB E1 increased ARR 5 stability, suggesting that the ubiquitin ligase that promotes ARR 5 proteolysis requires RUB modification for optimal activity.