Offsetting pb induced oxidative stress in Vicia faba plants by foliar spray of chitosan through adjustment of morpho-biochemical and molecular indices

Abstract

In the course of their life, plants face a multitude of environmental anomaly that affects their growth and production. In recent decades, lead (Pb) gained an increasing attention as it is among the most significant contaminants in the environment. Therefore, in this study the effects of Pb concentrations (0, 50 and 100 ppm) on Vicia faba plants and attempts to alleviate this stress using chitosan (Chs; 0 and 0.1%) were performed. The results validated that with increasing Pb concentrations, a decline in growth, pigments and protein contents was observed. In the same time, a significant upsurge in the stress markers, both malondialdehyde (MDA) and H₂O₂, was observed under Pb stress. Nonetheless, foliar spraying with Chs improves the faba bean growth, pigment fractions, protein, carbohydrates, reduces MDA and H₂O₂ contents and decreases Pb concentrations under Pb stress. Pb mitigation effects by Chs are probably related with the activity of antioxidant enzymes, phenylalanine ammonia lyase (PAL) and proline. The application of Chs enhanced the activities of peroxidase, catalase and PAL by 25.77, 17.71 and 20.07%, respectively at 100 ppm Pb compared to their control. Plant genomic material exhibits significant molecular polymorphism, with an average polymorphism of 91.66% across all primers. To assess the genetic distance created among treatments, the dendrogram was constructed and the results of the similarity index ranged from 0.75 to 0.95, indicating genetic divergence. Our research offers a thorough comprehension of the role of Chs in lessening the oxidative stress, which will encourage the use of Chs in agricultural plant protection.

Keywords: Vicia faba; Antioxidant; Chitosan; ISSR marker; Lead stress; Oxidative stress; Phenylalanine ammonia lyase.

Fig. 1

Effect of Chs application on V. faba plants grown under different Pb concentrations. T1: Control, T2: Chs, T3: 50 ppm Pb, T4: Chs + 50 ppm Pb, T5: 100 ppm Pb, T6: Chs + 100 ppm Pb

Fig. 2

Effect of Chs application on (a) protein and (b) carbohydrates contents of V. faba plants grown under different Pb concentrations. T1, T3 and T5 represent V. faba plants grown under 0, 50 and 100 ppm Pb concentrations, while T2, T4 and T6 represent V. faba plants foliar sprayed by Chs under 0, 50 and 100 ppm Pb concentrations. Results are the mean of three replicates ± SE. Different letters above bars indicate significant differences between the treatments and control plants (p < 0.05) as measured by Duncan test

Fig. 3

Effect of Chs application on (a) lipid peroxidation (malondialdehyde, MDA) and (b) hydrogen peroxide (H₂O₂) contents of V. faba plants grown under different Pb concentrations. T1, T3 and T5 represent V. faba plants grown under 0, 50 and 100 ppm Pb concentrations, while T2, T4 and T6 represent V. faba plants foliar sprayed by Chs under 0, 50 and 100 ppm Pb concentrations. Results are the mean of three replicates ± SE. Different letters above bars indicate significant differences between the treatments and control plants (p < 0.05) as measured by Duncan test

Fig. 4

Effect of Chs application on the activity of (a) catalase (CAT), (b) peroxidase (POX), (c) phenylalanine ammonia lyase (PAL) and (d) proline contents of V. faba plants grown under different Pb concentrations. T1, T3 and T5 represent V. faba plants grown under 0, 50 and 100 ppm Pb concentrations, while T2, T4 and T6 represent V. faba plants foliar sprayed by Chs under 0, 50 and 100 ppm Pb concentrations. Results are the mean of three replicates ± SE. Different letters above bars indicate significant differences between the treatments and control plants (p < 0.05) as measured by Duncan test

Fig. 5

Effect of Chs application on Pb concentration in shoots V. faba grown under different Pb concentrations. T1, T3 and T5 represent V. faba plants grown under 0, 50 and 100 ppm Pb concentrations, while T2, T4 and T6 represent V. faba plants foliar sprayed by Chs under 0, 50 and 100 ppm Pb concentrations. Results are the mean of three replicates ± SE. Different letters above bars indicate significant differences between the treatments and control plants (p < 0.05) as measured by Duncan test

Fig. 6

Heatmap constructed between different measured parameters. T1, T3 and T5 represent V. faba plants grown under 0, 50 and 100 ppm Pb concentrations, while T2, T4 and T6 represent V. faba plants foliar sprayed by Chs under 0, 50 and 100 ppm Pb concentrations

Fig. 7

(a) The Inter Simple Sequence Repeats (ISSR) products of genomic DNA extracted from leaves of V. faba plants using six primers, where arrow indicating appearance or disappearance of bands (b) Matrix plot constructed using the Past-pc showing band number of amplified DNA markers produced by ISSR marker, C1-C3 for (AC)8GG, C4-C9 for (CTC)6, C10 to C14 for (TG)8AA, C15-C18 for (AG)8T, C19-C21 for (TG)8AA and C22-C27 for (CA)8T. T1, T3 and T5 represent V. faba plants grown under 0, 50 and 100 ppm Pb concentrations, while T2, T4 and T6 represent V. faba plants foliar sprayed by Chs under 0, 50 and 100 ppm Pb concentration

Fig. 8

(a) UPGAMA Distance tree based on Euclidean, constructed using the Past-pc, showing the genetic distance between different treatments. (b) PCA constructed using the Past-pc showing band number of amplified DNA markers produced by ISSR marker. C1-C3 for (AC)8GG, C4-C9 for (CTC)6, C10 to C14 for (TG)8AA, C15-C18 for (AG)8T, C19-C21 for (TG)8AA and C22-C27 for (CA)8T. T1, T3 and T5 represent V. faba plants grown under 0, 50 and 100 ppm Pb concentrations, while T2, T4 and T6 represent V. faba plants foliar sprayed by Chs under 0, 50 and 100 ppm Pb concentrations