AUTHOR=Zhu Yi-Fang , Guo Jinliang , Zhang Yang , Huang Chao-Feng 

TITLE=The THO/TREX Complex Component RAE2/TEX1 Is Involved in the Regulation of Aluminum Resistance and Low Phosphate Response in Arabidopsis

JOURNAL=Frontiers in Plant Science

VOLUME=12

YEAR=2021

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2021.698443

DOI=10.3389/fpls.2021.698443

ISSN=1664-462X

ABSTRACT=<p>The C2H2-type zinc finger transcription factor SENSITIVE TO PROTON RHIZOTOXICITY 1 (STOP1) plays a critical role in aluminum (Al) resistance and low phosphate (Pi) response mainly through promoting the expression of the malate transporter-encoding gene <italic>ARABIDOPSIS THALIANA ALUMINUM ACTIVATED MALATE TRANSPORTER 1 (AtALMT1)</italic>. We previously showed that REGULATION OF ATALMT1 EXPRESSION 3 (RAE3/HPR1), a core component of the THO/TREX complex, is involved in the regulation of nucleocytoplasmic <italic>STOP1</italic> mRNA export to modulate Al resistance and low Pi response. Here, we report that RAE2/TEX1, another core component of the THO complex, is also involved in the regulation of Al resistance and low Pi response. Mutation of <italic>RAE2</italic> reduced the expression of STOP1-downstream genes, including <italic>AtALMT1</italic>. <italic>rae2</italic> was less sensitive to Al than <italic>rae3</italic>, which was consistent with less amount of malate secreted from <italic>rae3</italic> roots than from <italic>rae2</italic> roots. Nevertheless, low Pi response was impaired more in <italic>rae2</italic> than in <italic>rae3</italic>, suggesting that RAE2 also regulates AtALMT1-independent pathway to modulate low Pi response. Furthermore, unlike RAE3 that regulates <italic>STOP1</italic> mRNA export, mutating <italic>RAE2</italic> did not affect <italic>STOP1</italic> mRNA accumulation in the nucleus, although STOP1 protein level was reduced in <italic>rae2</italic>. Introduction of <italic>rae1</italic> mutation into <italic>rae2</italic> mutant background could partially recover the deficient phenotypes of <italic>rae2</italic>. Together, our results demonstrate that RAE2 and RAE3 play overlapping but distinct roles in the modulation of Al resistance and low Pi response.</p>