AUTHOR=Sotta Naoyuki , Sakamoto Takuya , Kamiya Takehiro , Tabata Ryo , Yamaguchi Katsushi , Shigenobu Shuji , Yamada Masashi , Hasebe Mitsuyasu , Sawa Shinichiro , Fujiwara Toru 

TITLE=NAC103 mutation alleviates DNA damage in an Arabidopsis thaliana mutant sensitive to excess boron

JOURNAL=Frontiers in Plant Science

VOLUME=14

YEAR=2023

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2023.1099816

DOI=10.3389/fpls.2023.1099816

ISSN=1664-462X

ABSTRACT=<p>Excess boron (B) is toxic to plants and thereby causes DNA damage and cell death in root meristems. However, the underlying mechanisms which link boron and DNA damage remain unclear. It has been reported that the <italic>rpt5a-6</italic> mutant of the 26S proteasome is sensitive to excess boron, resulting in more frequent cell death in root meristem and reduced root elongation. In this study, we showed that a reduction in root growth in the <italic>rpt5a</italic> mutant in the presence of high boron levels is repressed by a mutation in NAC domain containing transcription factor NAC103, a substrate of the proteasome, which functions in the unfolded protein response pathway. The mutation in NAC103 alleviated excess-B-induced DNA damage and cell death in root meristems of the <italic>rpt5a</italic> mutant. Superoxide (<inline-formula><mml:math display="inline" id="im1" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msubsup><mml:mi>O</mml:mi><mml:mi>2</mml:mi><mml:mi>−</mml:mi></mml:msubsup></mml:mrow></mml:math></inline-formula>) staining with nitroblue tetrazolium revealed that boron stress causes <inline-formula><mml:math display="inline" id="im2" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msubsup><mml:mi>O</mml:mi><mml:mi>2</mml:mi><mml:mi>−</mml:mi></mml:msubsup></mml:mrow></mml:math></inline-formula> accumulation in root tips, which was higher in the <italic>rpt5a-6</italic> mutant, whereas the accumulation was lower in the <italic>rpt5a-6 nac103-3</italic> double mutant. Our work demonstrates the overall involvement of <italic>NAC103</italic> in maintaining healthy root meristem under excess boron conditions in the absence of <italic>RPT5A</italic> proteasome subunit.</p>