Journal of Plant Pathology & Microbiology Research Article 1 J Plant Pathol Microbiol, Vol. 11 Iss. 10 No: 519 OPEN ACCESS Freely available online J o u r n a l o f P l a n t P a t h ol o g y & M i c r o b i o l o g y ISSN: 2157-7471 Effect of Phytoplasma Infection on Primary and Secondary Metabolites and Antioxidative Enzyme Activities of Sweet Orange (Citrus sinenses L.) Asia Rasool 1 , Muhammad Shah Jahan 2 , Umbreen Shazad 3 , Arsia Tariq 1 , Phoebe Nemenzo Calica 4 * 1 Government College University, Faisalabad, Layyah Campus, Punjab, Pakistan; 2 Agriculture College, Bahauddin Zakariya University, Bahadur Sub-Campus Layyah, Punjab, Pakistan; 3 Department of Plant Pathology, PMAS-Arid Agriculture University, Rawalpindi, Punjab, Pakistan; 4 Environmental Science Department, Ateneo de Davao University, Davao City, Philippines ABSTRACT Sweet orange (Citrus sinensis L.) is one of the most economically important citrus crops in the world and is the most commonly grown citrus fruit in the world. Nonetheless, its production is constantly threatened by pathogens that cause considerable economic losses and severe social impacts including phytoplasma. Phytoplasma is an emerging threat to sweet orange production which leads to severe yield losses worldwide. Phytoplasmas are phloem-limited pleomorphic bacteria, mainly transmitted through leafhoppers but also by plant propagation materials and seeds. This study aimed to evaluate the biochemical alterations in sweet orange plant as a response to phytoplasma infection. Phytoplasma-infected plants in this study, showed symptoms, such as yellowing of leaves, stunted and rolled foliage, unripened shoots and fruits, stunted roots or plant and “witches' broom”. Nested PCR confirmed the presence of phytoplasma in all the infected plants. Primary metabolites including chlorophyll a, b and total chlorophyll contents were significantly reduced. Meanwhile, carotenoid, proline and soluble protein were increased while soluble sugar, hydrogen peroxide and malondialdehyde were decreased in phytoplasma-infected plants. The secondary metabolites including phenolics, glycine betaine and anthocyanin were increased while ascorbic acid was decreased in the phytoplasma-infected plants. The activities of the antioxidative enzymes: ascorbate peroxidase, superoxide dismutase, catalase, and peroxidase activities were increased in phytoplasma-infected plants. On the basis of comparing our findings with previous reports, it is clear that the responses of host plants to phytoplasma infection are complex and may vary among plants. Keywords: Citrus sinensis L; Phytoplasma infection; Primary metabolites; Secondary metabolites; Antioxidative enzymes INTRODUCTION Sweet orange (Citrus sinensis L.) belongs to the family Rutaceae. It is a small, shallow-rooted evergreen shrub or tree growing about 6 - 13 meters tall with an enclosed conical top and mostly spiny branches [1]. Oranges are very wellknown fruit, widely available in countries around the world. The tree is commonly cultivated for its fruit in warm temperate, subtropical and tropical zones. It prefers a prominent change in the seasons and so is not so suited to the tropics, where it is grown more as a garden tree, but is widely grown commercially in the subtropics. Orange starts flowering and bearing fruit after 3-5 years. Trees aged 3-4 years produce 2.5-5 t/ha of fruit and 8-12 year old trees produce 20-40 t/ha of fruit. Single trees may live up to 100 years, but the economic is 30 years [1]. Orange fruits contain high concentrations of flavonoids beneficial to human health [2]. Citrus is the most economically important tree fruit crop in the world and orange is the most commonly grown citrus fruit in the world [3]. In 2018, 11.6 tonnes per hectare of oranges were grown in Pakistan [4]. The majority of citrus arrives at market in the form of processed products, such as single-strength orange juice and frozen juice concentrate [3]. Nonetheless, citrus production is constantly threatened by pathogens that cause considerable economic losses and severe social impacts. Among the major citrus diseases are phytoplasma-associated diseases [5]. The primary visible symptoms of these diseases are yellowing leaves, stunted and rolled foliage and unripened shoots and fruits. Other symptoms of phytoplasma infection might be stunted plants, stunted roots, aerial tubers, a “witches' broom” appearance on terminal new bud growth, and even die back of entire portions of the plant [6]. Witches' broom was first observed in Oman, and later was found to be present in United Arab Emirates [7], India [8] and Iran [9]. It occurs as an Correspondence to: Phoebe Nemenzo Calica, Environmental Science Department, Ateneo de Davao University, Davao City, Philippines, Tel: +63822212411; E-mail: pncalica@addu.edu.ph Received: September 01, 2020; Accepted: October 16, 2020; Published: October 23, 2020 Citation: Rasool A, Jahan MS, Shazad U, Tariq A, Calica PN (2020) Effect of Phytoplasma Infection on Primary and Secondary Metabolites and Antioxidative Enzyme Activities of Sweet Orange (Citrus sinenses L.). J Plant Pathol Microbiol 11:519. doi: 10.35248/2157-7471.20.11.519 Copyright: © 2020 Rasool A, et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.