Arabidopsis lonely guy (LOG) multiple mutants reveal a central role of the LOG‐dependent pathway in cytokinin activation
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<jats:title>Summary</jats:title><jats:p>Cytokinins are phytohormones that play key roles in the maintenance of stem cell activity in plants. Although alternative single‐step and two‐step activation pathways for cytokinin have been proposed, the significance of the single‐step pathway which is catalyzed by LONELY GUY (LOG), is not fully understood. We analyzed the metabolic flow of cytokinin activation in Arabidopsis <jats:italic>log</jats:italic> multiple mutants using stable isotope‐labeled tracers and characterized the mutants’ morphological and developmental phenotypes. In tracer experiments, cytokinin activation was inhibited most pronouncedly by <jats:italic>log7</jats:italic>, while the other <jats:italic>log</jats:italic> mutations had cumulative effects. Although sextuple or lower‐order mutants did not show drastic phenotypes in vegetative growth, the <jats:italic>log1log2log3log4log5log7log8</jats:italic> septuple T‐DNA insertion mutant in which the LOG‐dependent pathway is impaired, displayed severe retardation of shoot and root growth with defects in the maintenance of the apical meristems. Detailed observation of the mutants showed that <jats:italic>LOG7</jats:italic> was required for the maintenance of shoot apical meristem size. <jats:italic>LOG7</jats:italic> was also suggested to play a role for normal primary root growth together with <jats:italic>LOG3</jats:italic> and <jats:italic>LOG4</jats:italic>. These results suggest a dominant role of the single‐step activation pathway mediated by LOGs for cytokinin production, and overlapping but differentiated functions of the members of the <jats:italic>LOG</jats:italic> gene family in growth and development.</jats:p>
収録刊行物
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- The Plant Journal
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The Plant Journal 69 (2), 355-365, 2011-11-08
Wiley