Figure 4.

Germination of the ntm2-1 seeds is less sensitive to high salinity. A, NTM2 expression in germinating seeds. Seeds of transgenic plants expressing the pNTM2-GUS reporter were cold imbibed and allowed to germinate for 2 d on MS-agar plates containing 150 mm NaCl before GUS staining. B and C, Effects of high salinity on the germination of ntm2-1 seeds. Cold-imbibed seeds were germinated on MS-agar plates containing varying concentrations of NaCl and photographed 7 d after cold imbibition (B). Germination percentages were calculated 4 d after cold imbibition (C). Radicle emergence was used as a morphological marker for germination. Three measurements, each consisting of approximately 50 to 60 seeds, were averaged for each plant group. Error bars indicate se (* P < 0.01). S100, S150, and S200, NaCl at 100 mm, 150 mm, and 200 mm, respectively. D, Complementation of the ntm2-1 mutant. The ntm2-1 mutant was transformed with the NTM2 gene with its own promoter, resulting in pNTM2:NTM2/ntm2-1 (rescue). Two independent lines were subject to germination assays as described in B. E, Effects of ABA on the germination of ntm2-1 seeds. Germination assays were carried out as described in B, but ABA was used instead of NaCl. F, Effects of PAC on the germination of ntm2-1 seeds. Germination assays were carried out as described in B, but PAC was used instead of NaCl.