AUTHOR=Lim Benson , Smirnoff Nicholas , Cobbett Christopher S. , Golz John F. 

TITLE=Ascorbate-Deficient vtc2 Mutants in Arabidopsis Do Not Exhibit Decreased Growth

JOURNAL=Frontiers in Plant Science

VOLUME=7

YEAR=2016

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2016.01025

DOI=10.3389/fpls.2016.01025

ISSN=1664-462X

ABSTRACT=<p>In higher plants the <sc>L</sc>-galactose pathway represents the major route for ascorbate biosynthesis. The first committed step of this pathway is catalyzed by the enzyme GDP-<sc>L</sc>-galactose phosphorylase and is encoded by two paralogs in <italic>Arabidopsis</italic> – <italic>VITAMIN C2</italic> (<italic>VTC2</italic>) and <italic>VTC5</italic>. The first mutant of this enzyme, <italic>vtc2-1</italic>, isolated via an EMS mutagenesis screen, has approximately 20–30% of wildtype ascorbate levels and has been reported to have decreased growth under standard laboratory conditions. Here, we show that a T-DNA insertion into the <italic>VTC2</italic> causes a similar reduction in ascorbate levels, but does not greatly affect plant growth. Subsequent segregation analysis revealed the growth defects of <italic>vtc2-1</italic> mutants segregate independently of the <italic>vtc2-1</italic> mutation. These observations suggest that it is the presence of an independent cryptic mutation that affects growth of <italic>vtc2-1</italic> mutants, and not the 70–80% decrease in ascorbate levels that has been assumed in past studies.</p>