AUTHOR=Yang Liming , Ji Jianhui , Wang Hongliang , Harris-Shultz Karen R. , Abd_Allah Elsayed F. , Luo Yuming , Guan Yanlong , Hu Xiangyang 

TITLE=Carbon Monoxide Interacts with Auxin and Nitric Oxide to Cope with Iron Deficiency in Arabidopsis

JOURNAL=Frontiers in Plant Science

VOLUME=7

YEAR=2016

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2016.00112

DOI=10.3389/fpls.2016.00112

ISSN=1664-462X

ABSTRACT=<p>To clarify the roles of carbon monoxide (CO), nitric oxide (NO), and auxin in the plant response to iron deficiency (–Fe), and to establish how the signaling molecules interact to enhance Fe acquisition, we conducted physiological, genetic, and molecular analyses that compared the responses of various <italic>Arabidopsis</italic> mutants, including <italic>hy1</italic> (CO deficient), <italic>noa1</italic> (NO deficient), <italic>nia1/nia2</italic> (NO deficient), <italic>yuc1</italic> (auxin over-accumulation), and <italic>cue1</italic> (NO over-accumulation) to –Fe stress. We also generated a HY1 over-expression line (named HY1-OX) in which CO is over-produced compared to wild-type. We found that the suppression of CO and NO generation using various inhibitors enhanced the sensitivity of wild-type plants to Fe depletion. Similarly, the <italic>hy1</italic>, <italic>noa1</italic>, and <italic>nia1</italic>/<italic>nia2</italic> mutants were more sensitive to Fe deficiency. By contrast, the <italic>yuc1</italic>, <italic>cue1</italic>, and HY1-OX lines were less sensitive to Fe depletion. The <italic>hy1</italic> mutant with low CO content exhibited no induced expression of the Fe uptake-related genes <italic>FIT1</italic> and <italic>FRO2</italic> as compared to wild-type plants. On the other hand, the treatments of exogenous CO and NO enhanced Fe uptake. Likewise, <italic>cue1</italic> and HY1-OX lines with increased endogenous content of NO and CO, respectively, also exhibited enhanced Fe uptake and increased expression of bHLH transcriptional factor FIT1as compared to wild-type plants. Furthermore, we found that CO affected auxin accumulation and transport in the root tip by altering the PIN1 and PIN2 proteins distribution that control lateral root structure under –Fe stress. Our results demonstrated the integration of CO, NO, and auxin signaling to cope with Fe deficiency in <italic>Arabidopsis</italic>.</p>