Physiological and biochemical responses of two chili pepper (Capsicum annuum L.) genotypes to heavy metal stress

Aseel Hakim Mahdi, Salma Khalid Yassen, Abdul Mueen Shabeeb Hamad

Abstract


Heavy metal contamination adversely affects plant growth by disrupting physiological and biochemical processes. This study evaluated the responses of two chili pepper (Capsicum annuum L.) genotypes (Cayenne and ID15) to combined nickel (Ni), lead (Pb), and cadmium (Cd) stress by assessing total leaf chlorophyll, total soluble sugar, and fruit protein contents. Significant differences were observed among genotypes, heavy metal treatments, and most genotype × treatment interactions. Cayenne maintained significantly higher total leaf chlorophyll (2.782 mg g-1 fresh weight) than ID15 (2.532 mg g-1), indicating greater tolerance to heavy metal-induced damage to the photosynthetic apparatus. Chlorophyll content declined progressively with increasing heavy metal concentrations, from 4.129 mg g-1 in the control to 2.115 mg g-1 under severe stress. In contrast, ID15 accumulated slightly higher soluble sugars (2.544%) than Cayenne (2.490%), while sugar content initially increased under low metal stress (2.942%) before declining to 2.087% at the highest metal level, reflecting impaired carbohydrate metabolism under severe toxicity. Genotype had no significant effect on fruit protein content; however, heavy metal treatments significantly reduced protein concentration from 1.362% in the control to 0.880% under the highest stress level, indicating inhibition of nitrogen metabolism and enhanced protein degradation. Significant genotype × treatment interactions further demonstrated contrasting adaptive responses of the two genotypes. Overall, Cayenne exhibited greater tolerance through superior chlorophyll retention, whereas ID15 showed relatively better osmotic adjustment through soluble sugar accumulation. These findings highlight genotype-dependent mechanisms of heavy metal tolerance and provide useful information for selecting chili pepper genotypes suitable for cultivation in metal-contaminated soils.

Keywords


Capsicum annuum L., Heavy metal stress, Physiological responses, Biochemical responses, Stress tolerance

Full Text:

PDF

References


Abbas, M.F., Abbas, M.J., 1992. Practical Handling and Storage of Fruits and Vegetables. Ministry of Higher Education and Scientific Research, University of Basrah, Dar Al-Hikma Printing Press, Iraq.

Ali, M., Kumar, D., Sharma, R., Parkirti, Sharma, A., Manhas, R.K., Kapoor, N., Bhardwaj, R. and Ohri, P., 2024. Morphological, physiological and cellular responses of plants to cadmium toxicity. In Plant Responses to Cadmium Toxicity: Insights into Physiology and Defense Mechanisms (pp. 89-108). Cham: Springer Nature Switzerland.

Al-Rawi, K.M., Khalaf Allah, A.M., 1980. Design and analysis of agricultural experiments. University of Mosul, Ministry of Higher Education and Scientific Research, Dar Alkutub for Printing and Publishing, Republic of Iraq. pp. 214.

Al-Rubaie, B.J.H., 2021. Heavy Metals and Their Effects on Plants, 1st ed., Part 1. College of Agriculture, Al-Muthanna University, Iraq. ISBN: 978-9922-9402-8-1.

Altaf, M.A., Hao, Y., He, C., Mumtaz, M.A., Shu, H., Fu, H. and Wang, Z., 2022. Physiological and biochemical responses of pepper (Capsicum annuum L.) seedlings to nickel toxicity. Frontiers in Plant Science, 13, p.950392.

Altaf, M.A., Shahid, R., Ren, M.X., Altaf, M.M., Jahan, M.S., Khan, L.U., 2021. Melatonin mitigates nickel toxicity by improving nutrient uptake fluxes, root architecture system, photosynthesis, and antioxidant potential in tomato seedling. Journal of Soil Science and Plant Nutrition 21, 1842-1855.

Barboza, G.E., Carrizo García, C., Bianchetti, L.D.B., Romero, M.V., Scaldaferro, M., 2022. Monograph of wild and cultivated chili peppers (Capsicum L., Solanaceae). PhytoKeys 200, 1-423.

Barrita, J.L.S., Sánchez, M., 2013. Antioxidant role of ascorbic acid and its protective effects on chronic diseases oxidative stress. In: Chronic Degenerative Diseases: Role of Antioxidants, pp. 449-484.

Brahim, N., Hassen, M., Lajnef, M., 2024. Oxidative stress responses in plants exposed to heavy metal pollution. Environmental and Experimental Botany 210, 105012.

Chakrabarty, R., Das, S., Das, P., 2017. Nutritional benefits and pharmaceutical potentialities of chili: A review. Food and Agriculture Spectrum Journal 4, 11-18.

Cheng, C., Liu, J., Liu, J., Gao, Z., Yang, Y., Zhu, B., Yao, F. and Ye, Q., 2025. Selenium Alleviates Cadmium Toxicity in Pepper (Capsicum annuum L.) by Reducing Accumulation, Enhancing Stress Resistance, and Promoting Growth. Plants, 14(9), p. 1291.

El-Sappah, A.H., Li, J., Yan, K., Zhu, C., Huang, Q., Zhu, Y., Chen, Y., El-Tarabily, K.A., AbuQamar, S.F., 2024. Fibrillin gene family and its role in plant growth, development, and abiotic stress. Frontiers in Plant Science 15, 1453974.

Joslyn, M.N., 1970. Methods in Food Analysis, 2nd ed. Academic Press, New York.

Liu, Y., Chen, S., Zhao, W., Wang, Z., Guo, Y., 2021. Impact of heavy metals on nutrient uptake in plants: A review. Ecotoxicology and Environmental Safety 223, 112529.

Lowry, O.H., Rosebrough, N.J., Farr, A.L., Randall, R.J., 1951. Protein measurement with the Folin phenol reagent. Journal of Biological Chemistry 193, 265-275.

Mahdavian, K., Ghaderian, S.M., Schat, H., 2021. Effect of cadmium and lead on growth and physiology of Capsicum annuum. Environmental Science and Pollution Research 28, 1582-1590.

Neto, L.B., Paiva, A.S., Machado, R.D., Arenhart, R.A., Pinheiro, M.M., 2017. Interaction between plant hormones and heavy metal responses. Genetics and Molecular Biology 40, 373-386.

Sana, S., Ramzan, M., Ejaz, S., Danish, S., Salmen, S.H. and Ansari, M.J., 2024. Differential responses of chili varieties grown under cadmium stress. BMC Plant Biology, 24(1), p.7.

Schacterle, G.R., Pollak, E., 1973. A simplified method for the quantitative assay of small amounts of protein in biological samples. Analytical Biochemistry 51, 654-655.

Tripodi, P., 2024. Genomic structure and marker-trait association for plant and fruit traits in Capsicum chinense and Capsicum baccatum germplasm. BMC Research Notes 17, 231.

Usman, S., Shah, A.A., Kaleem, M., Noreen, Z., Xu, W., Mahmoud, E.A. and Elansary, H.O., 2025. Chitosan-Copper Nanocomposites Exterminate Cd Toxicity in Capsicum annuum L. through Improving Photosynthetic Attributes, Antioxidant Defense, and Reduced Cd Uptake. ACS omega, 10(30), pp.32879-32894.

Wang, T., Yang, Z., Li, Y., Wang, H. and Wang, H., 2026. Multiple defense networks in cadmium-excluding plants: from adaptive mechanisms to agricultural applications. Annals of Botany, p.mcag210.

Yang, Y., Wang, S., Zhao, C., Jiang, X., Gao, D., 2024. Responses of non-structural carbohydrates under heavy metal treatment. Science of the Total Environment 906, 168559.

Zaki, M., Habib, A., Hakmaoui, A., Debbi, F., Ouatmane, A., 2013. Assessment of color, capsaicinoids, carotenoids and fatty acid composition in paprika produced from Moroccan pepper cultivars (Capsicum annuum L.). Assessment 3, 111-119.

Zulfiqar, F., Moosa, A., Alshehri, D., Younis, T., Sadique, M.A., Alghanem, S.M.S., Rehman, T., Usama, H.M., Chen, J., Şimşek, Ö. and ul Zahra, U., 2024. Trehalose and melatonin interactions alleviate cadmium-incited oxidative stress via activating defense related genes and improve ornamental pepper growth. Plant Growth Regulation, 104(3), pp.1549-1562.




DOI: https://doi.org/10.33804/pp.010.04.6195

Refbacks

  • There are currently no refbacks.