The nramp1-1 Knockout Allele of NRAMP1 Is Hypersensitive to Mn Deficiency.
(A) The nramp1-1 mutant contains a T-DNA inserted in the 9th exon of the NRAMP1 gene and results in complete loss of accumulation of NRAMP1 mRNA as shown by RT-PCR.
(B) Test of tolerance to Mn deficiency of wild-type and nramp1-1 plants grown in vitro for 14 d either in Mn-replete conditions (20 μM MnSO4), in Mn-free medium (no added Mn), or in Mn excess medium (750 μM MnSO4) as indicated.
(C) Biomass production of plants grown as in (B). Data are from one representative experiment (n = 2). Error bars represent sd. **, Significant difference between the wild type and nramp1-1, P < 0.001, n = 8 (Student's t test). FW, fresh weight.
(D) Root elongation rate of wild-type and nramp1-1 plants grown in vitro in either Mn-replete (+Mn, 20 μM MnSO4) or Mn-free (−Mn, no added Mn) medium. Values are the means of 20 plants. Data are from one representative experiment (n = 2). Error bars represent sd.