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(A) Gene structure ofSTAR2. STAR2contains one exon and no introns. (B) Phylogenetic relationship of the STAR2 protein with homologs in maize,Arabidopsis, V. vinefera, P. patens, T. ethanolicus, and E. coli.The sequences used to generate the phylogeny are presented in Supplemental Data Set 2 online. Bootstrap values from 1000 trials are indicated. The 0.1 scale shows substitution distance. (C)Relative root transcript level ofSTAR2in two independent transgenic RNAi lines, 52-4 and 97-1. Actin1was used as an internal control, and values are relative to the level ofSTAR2in the vector control. (D) Effect ofSTAR2suppression by RNAi silencing on aluminum tolerance. The seedlings (four leaves stage) were exposed to a solution without aluminum for 1 d and then to a solution with 100mM aluminum for another day. The relative root elongation (root elongation with Al/root elongation without Alx100) is shown. Data are means6SDof biological replicates (n= 6).