Bacillus megaterium strain A12 ameliorates salinity stress in tomato plants through multiple mechanisms

Figures & data

Table 1. Changes in growth parameters of tomato plants under influence of salinity and BMA12.

Parameters	With salinity		Without salinity
	Control	BMA12	Control	BMA12
Plant height (cm)	21.36 ± 1.32^D	29.34 ± 1.70^BC	33.85 ± 1.25^B	41.58 ± 2.78^A
Root length (cm)	09.58 ± 05.36^D	13.87 ± 0.83^C	19.27 ± 0.73^B	26.47 ± 1.07^A
Fresh biomass (g)	23.87 ± 1.07^D	38.57 ± 2.50^C	57.68 ± 3.29^B	74.05 ± 5.32^A
Dry biomass (g)	01.98 ± 0.28^CD	02.82 ± 0.19^C	4.33 ± 0.26^B	6.07 ± 0.44^A
Leaf area (cm^2)	11.28 ± 0.93^CD	13.56 ± 1.61^C	17.23 ± 0.99^B	21.58 ± 1.91^A

Note: Data presented here are mean values of replicates of same treatment. Vales with ± represents standard error. Capital letters represents level of significance as governed by ANOVA and DNMRT at p = 0.05.

Figure 1. Effect of Bacillus megaterium strain A12 (BMA12) and salinity stress on chlorophyll and carotenoids contents of tomato plants. Results provided here are mean values of two independent experiments. Vertical bard represents standard error. Small letters represent level of significance among different treatments as governed by ANOVA and DNMRT at = p ≥ 0.05.

Table 2. Change in the photosynthetic parameters of tomato plants under influence of salinity and BMA12.

Treatment	Photosynthetic rate (μmol m^−1 s^−1)	Transpiration rate (mmol m^−2 s^−1)	Stomatal conductance (mmol m^−2 s^−1)	WUE (μmol mol^−1)
Control	12.76 ± 0.64^B	7.96 ± 0.35^BC	0.62 ± 0.02^B	1.60 ± 0.30^AB
NaCl	07.49 ± 0.33^D	5.12 ± 0.71^D	0.41 ± 0.03^D	1.46 ± 0.29^C
BMA12	15.83 ± 0.71^A	8.65 ± 0.54^AB	0.74 ± 0.05^A	1.83 ± 0.68^A
BMA12 + NaCl	10.66 ± 0.62^BC	9.02 ± 0.60^A	0.51 ± 0.02^C	1.18 ± 0.75^D

Note: Data presented here are mean values of replicates of same treatment. Vales with ± represents standard error. Capital letters represents level of significance as governed by ANOVA and DNMRT at p = 0.05.

Table 3. Changes in activities of antioxidant enzymes in leaves of tomato plants under influence of salinity and BMA12.

Parameters	With salinity		Without salinity
	Control	BMA12	Control	BMA12
SOD (U g^−1 fresh weight)	157 ± 08.36^C	398 ± 23.87^A	127 ± 09.47^CD	236 ± 18.80^B
CAT (mm H2O2 min^−1)	08.36 ± 0.45^C	12.58 ± 1.77^A	06.57 ± 0.83^CD	10.15 ± 0.47^B
APX (mol ASA min^−1)	16.23 ± 1.73^D	37.92 ± 09.07^A	21.30 ± 1.28^C	28.58 ± 1.31^B
POD (µmol oxidized guaicol)	09.54 ± 0.32^D	14.80 ± 0.67^B	12.58 ± 0.59^C	17.20 ± 1.36^A
PPO (µmol quinones)	05.36 ± 0.38^C	11.36 ± 0.75^B	12.57 ± 0.43^B	19.48 ± 1.20^A
H2O2 (µmol/g FW)	2.87 ± 0.16^A	1.59 ± 0.38^B	1.03 ± 0.02^CD	1.26 ± 0.07^BC

Note: Data presented here are mean values of replicates of same treatment. Vales with ± represents standard error. Capital letters represents level of significance as governed by ANOVA and DNMRT at p = 0.05.

Table 4. Changes in reduced and oxidized ascorbate and glutathione contents in the leaves of tomato plants under influence of salinity and BMA12.

Parameters	With salinity		Without salinity
	Control	BMA12	Control	BMA12
ASC (nmol/g fresh weight)	387.5 + 12.64^A	236.8 + 09.76^B	118.3 + 05.21^C	123.9 + 07.66^C
DHA (nmol/g fresh weight)	143.3 + 10.57^B	169.6 + 05.66^A	109.3 + 04.90^CD	123.6 + 07.81^C
GSH (mmol/g fresh weight)	01.67 + 0.23^B	03.38 + 0.19^A	00.96 + 0.07^C	01.12 + 0.09^BC
GSSG (mmol/g fresh weight)	0.367 + 0.02^B	0.58 + 0.04^A	0.26 + 0.02^CD	0.31 + 0.02^BC

Note: Data presented here are mean values of replicates of same treatment. Vales with ± represents standard error. Capital letters represents level of significance as governed by ANOVA and DNMRT at p = 0.05.

Figure 2. Effect of Bacillus megaterium strain A12 (BMA12) and salinity stress on phytohormones profile of tomato plants. Results provided here are mean values of two independent experiments. Vertical bard represents standard error. Small letters represent level of significance among different treatments as governed by ANOVA and DNMRT at = p ≥ 0.05.

Figure 3. Effect of Bacillus megaterium strain A12 (BMA12) and salinity stress on expression of some photosynthesis and redox homeostasis related genes of tomato plants. Gene expression was analyzed one week after treatments applications. Results provided here are mean values of two independent experiments. Vertical bard represents standard error. * represents level of significance among different treatments as governed by ANOVA. (* = p ≥ 0.05, ** = p ≥ 0.01).

Table 5. Changes in soluble sugar contents, soluble protein contents, free amino acid contents and some stress related metabolites in tomato plants under influence of salinity and BMA12.

Parameters	With salinity		Without salinity
	Control	BMA12	Control	BMA12
SSC (mg g^−1 FW)	77.28 ± 8.37^D	128.26 ± 7.63^B	102.40 ± 9.34^BC	136.39 ± 12.70^A
SPC (mg g^−1 FW)	06.98 ± 4.36^C	11.15 ± 0.62^B	12.07 ± 1.51^B	15.28 ± 0.88^A
FAAC (mg g^−1 FW)	13.25 ± 1.25^CD	16.39 ± 1.50^C	21.84 ± 1.67^B	29.35 ± 2.48^A
SC (µg g^−1 FW)	08.37 ± 0.64^D	13.25 ± 0.86^B	11.67 ± 1.33^BC	17.98 ± 0.95^A
PC (µmol g^−1 FW)	05.67 ± 0.68^B	07.27 ± 0.40^A	03.35 ± 0.27^C	4.91 ± 0.58^B
ß-carotene (µg g^−1 FW)	0.29 ± 0.032^D	0.37 ± 0.019^C	0.58 ± 0.067^AB	0.62 ± 0.081^A

Note: Data presented here are mean values of replicates of same treatment. Vales with ± represents standard error. Capital letters represents level of significance as governed by ANOVA and DNMRT at p = 0.05.

Figure 4. Changes in metabolomics of tomato plants induced by Effect of Bacillus megaterium strain A12 (BMA12) and salinity stress. Metabolites were quantified by UPLC/ESI MS/MS after one week after treatments applications. Metabolites were extracted from leaf samples of tomato plants. Results provided here are mean values of two independent experiments.

Figure 5. Possible mechanisms of induced salinity tolerance in tomato plants mediated by Bacillus megaterium strain A12 (BMA12).