Fig. 4.
CH4- and PEG-induced NO production was sensitive to the PTIO, and the alleviation caused by CH4 was sensitive to tungstate and L-NAME. Mung bean seeds were presoaked with solutions containing 1.3 mM CH4, 100 μM SNP, 100 μM old SNP, 500 μM PTIO, 1 mM tungstate, 500 μM L-NAME, alone or their combinations for 12 h, and then shifted to 20% PEG-6000 for another 12 h. Afterwards, about 200 μm transversal sections from the root tips were loaded with 4-amino-5-methylamino-2’,7’-difluorofluorescein diacetate (DAF-FM DA), and detected by laser scanning confocal microscopy (LSCM; a). Bars = 25 μm. DAF-FM DA fluorescence densities according to (a) were also given (b). At least six individual samples were randomly selected and measured per treatment. Meanwhile, the content of NO in root tissues was determined by Griess reagent assay (c). Besides, the relationship between CH4 and tungstate, L-NAME was also analysed (d). Treatment with distilled water was regarded as control (Con). Data are means ± SE of three independent experiments with at least three replicates for each. Bars with different letters denote significant difference at P < 0.05 according to Duncan’s multiple range test