The CaM KMT KO Mutant Shows Increased Resistance to Salt Stress during Germination and Early Seedling Growth.
(A) to (C) Germination of seeds of the mutant KO lines under NaCl stress conditions occurred earlier than for Col-0 and CaM KMT OX-7 lines. Seeds were placed on AGM without (A) or with 150 (B) and 200 mM (C) NaCl, and germination was measured after the indicated period. After stratification at 4°C for 2 d, the plates were transferred to a growth chamber (16-h-light/8-h-dark cycle at 22°C). For the phenotypic measurement of germination, seeds with a protruding radicle were scored daily from days 1 through 6 after stratification. All assays were repeated three times using ∼50 seeds for each experiment. Values are mean ± sd (n = 3).
(D) and (E) Cotyledon greening under NaCl stress of the mutant KO and OX-7 seedlings occurred sooner and later, respectively, than that of Col-0. Col-0, KO, and OX-7 seeds were placed on AGM without (D) or with 150 mM NaCl (E), and cotyledon greening was measured after the indicated period. After stratification at 4°C for 2 d, the plates were transferred to a growth chamber (16-h-light/8-h-dark cycle at 22°C) and subsequently analyzed. The seedlings with green cotyledons were scored daily from days 1 through 7 after stratification. All assays were repeated three times using ∼50 seeds for each experiment. Values are mean ± sd (n = 3).
(F) Phenotypes of seedlings of the Col-0, KO, and OX-7 lines grown without (0) or with the indicated concentrations of NaCl. Photos were taken 3 d after stratification. Bar = 1 mm.
(G) Effect of salt stress on root growth of seedlings of the different lines. After stratification, the Col-0, KO, RNAi-6, and OX-7 seeds were sown in AGM for 4 d, and subsequently two seedlings of each type were grown vertically in AGM without or with 100 mM NaCl for an additional 7 d before being photographed. OX-7 lines showed stunted growth and reduced lateral root formation (indicated by red arrow). The experiment was repeated at least three times with similar results.