Promoting effect of biogenic AgNPs on Echinops macrochaetus for improving growth parameters and mitigating the toxic effect caused by salinity stress

Figures & data

Figure 1. Characterization of biogenically synthesized AgNPs: (a) transmission electron microscopy (TEM); (b) Fourier transmission infrared (FTIR) spectroscopy (transmittance versus wavenumber); (c) UV-visible spectrum (absorbance versus wavelength; (d) zeta potential (total count versus apparent zeta potential).

Figure 2. Percentage seed germination of E. macrochaetus; C (Control, distilled water); Ag-40 (40 µmol/L AgNPs); Ag-80 (80 µmol/L AgNPs); Ag-160 (160 µmol/L AgNPs); Ag-300 (300 µmol/L AgNPs); Ag-400 (400 µmol/L AgNPs); NaCl-40 (40 mmol/L NaCl); NaCl-80 (80 mmol/L NaCl) and NaCl-120 (120 mmol/L NaCl). The percentage germination was determined on day 7 after sowing.

Figure 3. Plumule and radicle lengths in germinated seeds of E. macrochaetus; (a) Control; (b) 40 µmol/L AgNPs; (c) 80 µmol/L AgNPs; (d) 160 µmol/L AgNPs; (e) 300 µmol/L AgNPs; (f) 400 µmol/L AgNPs; (g) 40 mmol/L NaCl; (h) 80 mmol/L NaCl; (i) 120 mmol/L NaCl. Note: Seed priming with AgNPs (24 h) and unprimed seeds germinated under salt solution (seven days). Pictures were taken on the seventh day after sowing.

Figure 4. Effect of biogenic AgNPs and NaCl on plumule and radicle lengths in seed germination study. C (Control, distilled water); Ag-40 (40 µmol/L AgNPs); Ag-80 (80 µmol/L AgNPs); Ag-160 (160 µmol/L AgNPs); Ag-300 (300 µmol/L AgNPs); Ag-400 (400 µmol/L AgNPs); NaCl-40 (40 mmol/L NaCl); NaCl-80 (80 mmol/L NaCl) and NaCl-120 (120 mmol/L NaCl); data are means of three replicates (mean ± SD). Different letters on bar graph indicate significant differences (p < .05). Note: Measurements were made on the seventh day after sowing.

Figure 5. Morphological characteristics of E. macrochaetus with AgNPs and NaCl treatment in pot experiment; (a) T1p (Control, distilled water); (b) T2p (40 µmol/L AgNPs); (c) T3p (80 µmol/L AgNPs); (d) T4p (40 mmol/L NaCl); (e) T5p (80 mmol/L NaCl); (f) T6p (120 mmol/L NaCl); (g) T7p (40 mmol/L NaCl + 40 µmol/L AgNPs); (h) T8p (80 mmol/L NaCl + 40 µmol/L AgNPs); (i) T9p (120 mmol/L NaCl + 40 µmol/L AgNPs); (j) T10p (40 mmol/L NaCl + 80 µmol/L AgNPs); (k) T11p (80 mmol/L NaCl + 80 µmol/L AgNPs); (l) T12p (120 mmol/L NaCl + 80 µmol/L AgNPs). Note: Treatment duration was 90 days and photographs were taken after 120 days of sowing.

Table 1. Effect of biogenic AgNPs alone and in combined treatment (AgNPs + NaCl) on biomass of different parts of E. macrochaetus.

Treatment	Root FW (g)	Root DW (g)	Leaves FW (g)	Leaves DW (g)	Stem FW (g)	Stem DW (g)	Shoot length (cm)
T1p	2.36 ± 0.15^d	0.56 ± 0.03 ^cd	17.85 ± 1.22^b	4.67 ± 0.03^c	3.28 ± 0.11^b	0.58 ± 0.02^b	5.99 ± 0.57^de
T2p	5.00 ± 0.52^a	0.86 ± 0.01^a	25.11 ± 0.67^a	6.18 ± 0.36^ab	5.70 ± 0.51^a	0.61 ± 0.02^a	8.81 ± 0.53^a
T3p	4.23 ± 0.10^b	0.56 ± 0.02^a	23.10 ± 0.82^a	6.67 ± 0.22^a	5.58 ± 0.14^a	0.54 ± 0.01^a	8.73 ± 0.15^a
T4p	3.66 ± 0.20c	0.64 ± 0.01^a	23.56 ± 0.57^a	5.70 ± 0.75^b	3.65 ± 0.26^b	0.45 ± 0.01^c	7.46 ± 0.9b^c
T5p	2.23 ± 0.11^d	0.42 ± 0.00^b	14.52 ± 0.63 ^cd	3.70 ± 0.23^d	2.76 ± 0.28^c	0.37 ± 0.01^d	4.36 ± 0.40^f
T6p	1.63 ± 0.15^e	0.34 ± 0.03^e	12.15 ± 1.11^e	2.56 ± 0.19^e	1.80 ± 0.04^e	0.43 ± 0.01^f	2.70 ± 0.10^g
T7p	4.76 ± 0.47^ab	0.81 ± 0.06^a	24.15 ± 0.22^a	6.12 ± 0.39^ab	3.58 ± 0.23^b	0.48 ± 0.01^c	8.26 ± 0.40^ab
T8p	4.53 ± 0.20^ab	0.82 ± 0.04^b	16.63 ± 1.27^b	3.69 ± 0.23^d	2.90 ± 0.06^b	0.37 ± 0.11^c	6.63 ± 0.86 ^cd
T9p	3.60 ± 0.10^c	0.56 ± 0.02^bc	16.04 ± 2.24^bc	3.73 ± 0.25^d	2.33 ± 0.08^d	0.44 ± 0.01^e	5.46 ± 0.78^e
T10p	4.86 ± 0.45^a	0.76 ± 0.07^a	24.82 ± 0.57^a	4.93 ± 0.35^c	3.40 ± 0.17^b	0.43 ± 0.02^c	6.66 ± 0.23 ^cd
T11p	3.56 ± 0.15^c	0.53 ± 0.02^b	16.67 ± 1.52^b	3.70 ± 0.24^d	2.34 ± 0.10^d	0.32 ± 0.00^d	6.46 ± 0.66 ^cd
T12p	2.76 ± 0.45^d	0.36 ± 0.01^de	13.27 ± 1.00^de	2.76 ± 0.16^e	1.52 ± 0.04^e	0.27 ± 0.00^g	3.63 ± 0.25^fg

Notes: T1p (Control, distilled water); T2p (40 µmol/L AgNPs); T3p (80 µmol/L AgNPs); T4p (40 mmol/L NaCl); T5p (80 mmol/L NaCl); T6p (120 mmol/L NaCl); T7p (40 mmol/L NaCl + 40 µmol/L AgNPs); T8p (80 mmol/L NaCl + 40 µmol/L AgNPs); (i) T9p (120 mmol/L NaCl + 40 µM AgNPs); T10p (40 mmol/L NaCl + 80 µmol/L AgNPs); T11p (80 mmol/L NaCl + 80 µmol/L AgNPs); T12p (120 mmol/L NaCl + 80 µmol/L AgNPs). FW: fresh weight; DW: dry weight. Data are means of three replicates (mean ± SD). Different letters within each column indicate significant differences (p < .05).

Table 2. Proline content, total chlorophyll and antioxidant enzyme activities (APX and GR) in treated (AgNPs and NaCl) and untreated plants of E. macrochaetus.

Treatment	Proline (µg/g FW)	Chlorophyll content (µg/g FW)	APX (U/mg protein/min)	GR (U/mg protein/min)
T1p	95.30 ± 5.8^j	209.30 ± 0.87^b	0.32 ± 0.04^f	0.11 ± 0.02^f
T2p	99.70 ± 2.5^i	304.00 ± 5.56^a	0.41 ± 0.04e^f	0.11 ± 0.02^f
T3p	100.8 ± 3.4^h	214.18 ± 4.02^b	0.50 ± 0.01^def	0.28 ± 0.04^de
T4p	190.3 ± 7.6^g	152.36 ± 4.60^d	0.61 ± 0.03^de	0.19 ± 0.03^ef
T5p	227.5 ± 5.8^f	138.12 ± 6.47^e	0.86 ± 0.04^bc	0.31 ± 0.04 ^cd
T6p	291.4 ± 5.3^d	123.27 ± 4.17^f	1.03 ± 0.01^b	0.42 ± 0.00^ab
T7p	259.2 ± 4.1^e	165.191 ± 3.27^c	0.64 ± 0.03^cde	0.22 ± 0.07e
T8p	308.1 ± 9.4^d	162.81 ± 5.95^c	1.08 ± 0.04^b	0.39 ± 0.07^abc
T9p	356.4 ± 5.8^c	127.68 ± 0.44^f	1.39 ± 0.05^a	0.48 ± 0.06^a
T10p	402.0 ± 6.60^b	126.66 ± 2.40^f	0.67 ± 0.02 c^d	0.38 ± 0.01^bc
T11p	429.2 ± 6.9^a	103.56 ± 4.97^g	0.90 ± 0.06^b	0.47 ± 0.09^ab
T12p	340.0 ± 6.0^b	71.21 ± 1.51^h	0.92 ± 0.01^b	0.28 ± 0.05^de

Notes: T1p (Control, distilled water); T2p (40 µmol/L AgNPs); T3p (80 µmol/L AgNPs); T4p (40 mmol/L NaCl); T5p (80 mmol/L NaCl); T6p (120 mmol/L NaCl); T7p (40 mmol/L NaCl + 40 µmol/L AgNPs); T8p (80 mmol/L NaCl + 40 µmol/L AgNPs); T9p (120 mmol/L NaCl + 40 µmol/L AgNPs); T10p (40 mmol/L NaCl + 80 µmol/L AgNPs); T11p (80 mmol/L NaCl + 80 µmol/L AgNPs); T12p (120 mmol/L NaCl + 80 µmol/L AgNPs). Data are means of three replicates (mean ± SD). Different letters within each column represent significant differences (p < .05).

Figure 6. Histogram display of DNA content from leaves of E. macrochaetus measured by flow cytometry. Figures and their corresponding treatments; (a) T1p (Control, distilled water); (b) T2p (40 µmol/L AgNPs); (c) T3p (80 µmol/L AgNPs); (d) T4p (40 mmol/L NaCl); (e) T5p (80 mmol/L NaCl); (f) T6p (120 mmol/L NaCl); (g) T7p (40 mmol/L NaCl + 40 µmol/L AgNPs); (h) T8p (80 mmol/L NaCl + 40 µmol/L AgNPs); (i) T9p (120 mmol/L NaCl + 40 µmol/L AgNPs); (j) T10p (40 mmol/L NaCl + 80 µmol/L AgNPs); (k) T11p (80 mmol/L NaCl + 80 µmol/L AgNPs); (l) T12p (120 mmol/L NaCl + 80 µmol/L AgNPs).

Table 3. Assessment of genotoxicity in E. macrochaetus exposed to NaCl stress and biogenic AgNPs.

Treatment	DNA amount (pg) per 2C (G0/G1) (mean ± SD)	DNA amount (pg) per 4C S phase (mean ± SD)	Mitotic index (4C/2C)
T1p	2.252 ± 0.085^bc	3.965 ± 0.036^ab	1.761
T2p	2.005 ± 0.08^e	3.687 ± 0.122^cde	1.838
T3p	2.248 ± 0.08^b	3.978 ± 0.077^a	1.769
T4p	2.182 ± 0.00^bc	3.846 ± 0.048^abc	1.762
T5p	2.021 ± 0.09^de	3.542 ± 0.153^e	1.753
T6p	2.359 ± 0.06^a	3.969 ± 0.025^a	1.682
T7p	2.016 ± 0.02^e	3.800 ± 0.068^bc	1.885
T8p	2.011 ± 0.04^e	3.620 ± 0.078^de	1.799
T9p	2.144 ± 0.04^bcd	3.774 ± 0.064^bcd	1.760
T10p	2.224 ± 0.02^bc	3.990 ± 0.060^a	1.794
T11p	2.181 ± 0.06^bc	3.874 ± 0.032^ab	1.776
T12p	2.104 ± 0.08^bcd	3.626 ± 0.113^bcd	1.723

Notes: T1p (Control, distilled water); T2p (40 µmol/L AgNPs); T3p (80 µmol/L AgNPs); T4p (40 mmol/L NaCl); T5p (80 mmol/L NaCl); T6p (120 mmol/L NaCl); T7p (40 mmol/L NaCl + 40 µmol/L AgNPs); T8p (80 mmol/L NaCl + 40 µmol/L AgNPs); T9p (120 mmol/L NaCl + 40 µmol/L AgNPs); T10p (40 mmol/L NaCl + 80 µmol/L AgNPs); T11p (80 mmol/L NaCl + 80 µmol/L AgNPs); T12p (120 mmol/L NaCl + 80 µmol/L AgNPs). Data represent mean values from three biological replicates (mean ± SD). Different letters within each column denote significant differences (p < .05).

Data availability statement

The data supporting the findings of the present study are available in this article and are accessible from corresponding author upon reasonable request.