Ion contents of mtm1-i, mtm2, and mtm1-i
mtm2 mutant plants in response to MnCl2 treatment
To investigate the impact of metal ion homeostasis through AtMTM1 and
AtMTM2 that have been classified as the mitochondrial carriers (Picault,
Hodges, Palmieri, & Palmieri, 2004), we applied 100 μM
MnCl2 treatment on mtm1-i , mtm2 , andmtm1-i mtm2 mutants, and used ICP-OES to measure metal ion
contents. The index of metal retention ability represents the ratio of
the ion content in Mn treatment to that in control (Figure 13,
Supplemental Figure S15) .
The mtm1-i , mtm2 , and mtm1-i mtm2 mutant lines had
decreased Mn content in root compared with the WT under Mn treatment,
and mtm2 had lower Mn content before treatment (Figure
13A, top) . Specially, the mtm1-i mtm2 -double mutant had
decreased Mn retention ability by 1.3-fold in root compared with the WT.
On the contrary, all three mutants had increased Mn content in shoot
compared with the WT under Mn treatment (Figure 13A, bottom) ,
implying the discrepancy of Mn regulation was in root and shoot via
AtMTM1 and AtMTM2.
Altered Fe homeostasis with a reciprocal trend was also observed in root
and shoot of these single and double mutants under Mn treatment(Figure 13B) . Fe retention ability was reduced significantly in
root of these mutants, even in the control of mtm1-i mtm2 -double
mutant (Figure 13B, top) . On the contrary, all three mutants
had increased Fe content in shoot before and after treatments.
Particularly, the double mutant had increased Fe retention ability by
1.3-fold in shoot compared with the WT (Figure 13B, bottom) .
Taken together, the reciprocal regulation of Mn and Fe contents in root
and shoot were detected in single and double mutants, especially inmtm1-i mtm2 -double mutant, indicating Mn and Fe homeostasis are
closely regulated by AtMTM1 and AtMTM2. Besides, the fluctuations of
other metal contents and retention abilities of Ca, Mg, Zn, K, and Na
were observed in single or double mutants before or after Mn treatment(Supplemental Figure S15) , implying AtMTM1 andAtMTM2 may extensively affect cellular ion homeostasis.