The <i>Arabidopsis</i> transcription factor ABIG1 relays ABA signaled growth inhibition and drought induced senescence.

Liu, Tie; Longhurst, Adam D; Talavera-Rauh, Franklin; Hokin, Samuel A; Barton, M Kathryn · Elife · 2016

basic_science · Level V

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Abstract

Drought inhibits plant growth and can also induce premature senescence. Here we identify a transcription factor, ABA INSENSITIVE GROWTH 1 (ABIG1) required for abscisic acid (ABA) mediated growth inhibition, but not for stomatal closure. <i>ABIG1</i> mRNA levels are increased both in response to drought and in response to ABA treatment. When treated with ABA, <i>abig1</i> mutants remain greener and produce more leaves than comparable wild-type plants. When challenged with drought, <i>abig1</i> mutants have fewer yellow, senesced leaves than wild-type. Induction of ABIG1 transcription mimics ABA treatment and regulates a set of genes implicated in stress responses. We propose a model in which drought acts through ABA to increase <i>ABIG1</i> transcription which in turn restricts new shoot growth and promotes leaf senescence. The results have implications for plant breeding: the existence of a mutant that is both ABA resistant and drought resistant points to new strategies for isolating drought resistant genetic varieties.

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