Effect of Drought Stress on Capsaicin and Antioxidant Contents in Pepper Genotypes at Reproductive Stage

Tahir Mahmood; Rashid Mehmood Rana; Sunny Ahmar; Saima Saeed; Asma Gulzar; Muhammad Azam Khan; Fahad Masoud Wattoo; Xiukang Wang; Ferdinando Branca; Freddy Mora-Poblete; Gabrielle Sousa Mafra; Xionming Du

doi:10.3390/plants10071286

Effect of Drought Stress on Capsaicin and Antioxidant Contents in Pepper Genotypes at Reproductive Stage

Plants (Basel). 2021 Jun 24;10(7):1286. doi: 10.3390/plants10071286.

Affiliations

¹ Department of Plant Breeding and Genetics, PMAS-Arid Agriculture University, Rawalpindi 46000, Pakistan.
² Institute of Biological Sciences, Campus Talca, Universidad de Talca, Talca 3465548, Chile.
³ Department of Horticulture, PMAS-Arid Agriculture University, Rawalpindi 46000, Pakistan.
⁴ College of Life Sciences, Yan'an University, Yan'an 716000, China.
⁵ Department of Agriculture, Food and Environment (Di3A), University of Catania, 95123 Catania, Italy.
⁶ Centro de Ciências Agrárias, Universidade Estadual da Região Tocantina do Maranhão, R. Godofredo Viana, 1300, Imperatriz 65901-480, MA, Brazil.
⁷ State Key Laboratory of Cotton Biology, Institute of Cotton Research, Chinese Academy of Agricultural Sciences (ICR, CAAS), Anyang 455000, China.

Abstract

Pepper is one of the most important vegetables and spices in the world. Principal pungency is contributed by secondary metabolites called capsaicinoids, mainly synthesized in the placenta of pepper fruit. Various factors, including drought, limit pepper production. Flowering is one of the most sensitive stages affected by drought stress. The current study was conducted to determine the effect of drought on different pepper genotypes at the flowering and pod formation stages. Hot pepper (Pusajuala and Ghotki) and Bell pepper (Green Wonder and PPE-311) genotypes were subjected to drought (35% field capacity) at two different stages (flowering (DF) and pod formation (DP) stage). In comparison, control plants were maintained at 65% field capacity. The data regarding flowering survival rates, antioxidant protein activity, and proline content, were collected. Results indicated that parameters like flower survival percentage, number of fruits per plant, and fruit weight had significant differences among the genotypes in both treatments. A high proline level was observed in Green Wonder at the pod formation stage compared to other genotypes. Capsaicin contents of hot pepper genotypes were affected at the pod formation stage. Antioxidants like GPX were highly active (190 units) in Ghotki at pod formation. Bell pepper genotypes had a high APX activity, highly observed (100 units) in PPE-311 at pod formation, and significantly differ from hot pepper genotypes. In the catalase case, all the genotypes had the highest values in DP compared to control and DF, but Pusajuala (91 units) and Green Wonder (83 units) performed best compared to other genotypes. Overall, the results indicate that drought stress decreased reproductive growth parameters and pungency of pepper fruit as most of the plant energy was consumed in defense molecules (antioxidants). Therefore, water availability at the flowering and pod formation stage is critical to ensure good yield and pepper quality.

Keywords: ROS; antioxidant; capsaicin; drought; metabolomics; pepper; reactive oxygen species.

Grants and funding

1201973/The study was financially supported by the Chilean National Fund for Scientific and Technological 357 Development (FONDECYT) grant number 1201973.