Nitric oxide modulates polyamine homeostasis in sunflower seedling cotyledons under salt stress

Figures & data

Figure 1. (a,b) Modulation of spermine content in various fractions obtained from sunflower seedling (2 d old) cotyledons (as estimated post-dansylation followed by quantification of TLC fractions by spectrofluorometry). Statistical significance of changes was analyzed by one-way ANOVA using SPSS 22.0 and changes were found to be significant (*P < .05, **P < .001, ***P < .0001) in comparison to the control. Data represent mean values from triplicates. (c–f) Modulation of expression of PA biosynthetic enzymes [ADC (Arginine decarboxylase), ODC (Ornithine decarboxylase) and SAMDC (S-adenosylmethionine decarboxylase)] in seedling cotyledons by NaCl (120 mM) and NO donor (DETA, 250 μM) application.

Figure 2. Immunolocalization of the three PA biosynthetic enzymes ADC, ODC and SAMDC using CLSM. (a) Immunolocalization of the three PA biosynthetic enzymes was performed by CLSM imaging of 7 µm thick transverse sections of cotyledons harvested from 2 d-old-dark-grown seedlings raised in the absence or presence of salt stress (120 mM NaCl) or those raised in Hoagland nutrient medium supplemented with 250 µM of DETA in the absence or presence of 120 mM NaCl. (b–d) Quantification of fluorescence units for ADC, ODC and SAMDC, respectively. Statistical significance of changes was analyzed by one-way ANOVA using SPSS 22.0 and changes were found to be significant (*P < .05, **P < .001) in comparison to control. Data represent mean values from triplicates [Magnification: 200×; Scale bar: 60 µm].

Table 1. Alteration in the activity of the two polyamine catabolic enzymes, diamine oxidase (DAO) and polyamine oxidase (PAO) in sunflower seedling cotyledons in response to salt stress and treatment with NO donor (DETA). Data represent mean values from triplicates and the standard errors. Statistical significance of changes was analyzed by one-way ANOVA using SPSS 22.0 and changes were found to be significant (*P < .05, **P < .001) in comparison with control.

	Treatments		Specific activity (mol.µg^−Citation1 protein.min^−Citation1 × 10^−Citation10)
			Diamine oxidase	Polyamine oxidase
	Control	(−) NaCl	79.85 (± 5.26)	27.46 (± 4.38)
		(+) NaCl	86.71 (± 4.06)	55.38 (± 0.67)**
	DETA	(−) NaCl	87.32 (± 5.93)	45.91 (± 3.49)*
		(+) NaCl	86.56 (± 8.38)	39.26 (± 2.26)*

Figure 3. Nitric oxide and salt stress-mediated modulation of polyamine biosynthetic and catabolic routes.

Table

ABA	abscisic acid
ADC	arginine decarboxylase
DAO	diamine oxidase
dcSAM	decarboxylated S-adenosylmethionine
DETA	diethylenetriamine
GABA	γ-aminobutyric acid
NO	nitric oxide
ODC	ornithine decarboxylase
PA	polyamine
PAO	polyamine oxidase
Put	putrescine
SAM	S-adenosylmethionine
SAMDC	S-adenosylmethionine decarboxylase
Spd	spermidine
SPDS	spermidine synthase
Spm	spermine
SPMS	spermine synthase

Alcázar R, Altabella T, Marco F, Bortolotti C, Reymond M, Knocz C, Carrasco P, Tiburcio AF. Polyamines: molecules with regulatory functions in plant abiotic stress tolerance. Planta. 2010;231:1–6. PMID:20221631. doi:10.1007/s00425-010-1130-0.

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