Effect of Phosphorus on the Cadmium Transfer and ROS-scavenging Capacity of Rice Seedlings

Abstract

Environmental toxicity due to cadmium (Cd) pollution in croplands causes critical problems worldwide. Rice (Oryza sativa L.) is an important crop in Asia, including South Korea, and numerous studies have evaluated the relationship between Cd and antioxidants to alleviate Cd uptake from the soil into plants. However, information about the relationship between phosphorus (P) and antioxidants in rice seedlings is still limited with regard to Cd phytotoxicity. We therefore investigated the physiological responses of rice (Oryza sativa L. cv 'Dongjin') seedlings to Cd toxicity and the effect of P application on reactive oxygen species (ROS) and antioxidant changes. The exposure of rice seedlings to 30 µM Cd inhibited plant growth; increased the contents of superoxide, hydrogen peroxide, and malondialdehyde; and induced Cd uptake by the roots and leaves. Application of P to Cd-exposed seedlings decreased Cd-induced oxidative stress by enhancing the capacity of ascorbate (AsA) production and ROS-scavenging, and decreased Cd transfer from the roots to the leaves. These results suggest that P application alleviated Cd-induced growth inhibition and oxidative damage by restricting Cd translocation from the roots to the leaves and maintaining sufficient levels of AsA.Keywords: Antioxidant, Cadmium, Phosphorus, Reactive oxygen species (ROS), Rice ) in roots (A, C) and leaves (B, D) of rice plants grown in the 30 µM Cd-treated hydroponics with or without 6 mM phosphorus (P) application at the four-leaf stage after 14 days.Ⓒ The Korean Society of Soil Science and Fertilizer. This is an Open Access article distributed under the terms of the Creative Commons Attribution NonCommercial License (http://creativecommons.org/licenses/by-nc/4.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. Science and Fertilizer Vol. 50, No. 4, 2017 Introduction 세계적인 산업화 및 도시화는 농경지, 농업용수 그리고 생활용수 등의 오염수준을 급속히 증가시키고 있다 (Galiulin et al., 2001;Kirkham, 2006). 카드뮴 오염은 환경적으로 부정적인 영향을 끼칠 뿐만 아니라 먹이사슬의 최 정상에 위치한 인간의 건강을 위협하는 치명적인 위해요소로 간주되고 있다 (Jan et al., 2015;Nagajyoti et al., 2010). • Korean Journal of Soil카드뮴은 전반적인 식물생장에 부정적으로 작용하며 세포분열을 방해하여 뿌리의 신장을 억제할 뿐만 아니라 보조인 자로 필수금속이온 (Cu, Zn, Mn, Fe 등)을 포함한 단백질들의 금속이온을 치환함으로써 펜톤반응 (fenton reaction)활성산소종 (reactive oxygen species, ROS)을 발생시켜 세포 내에서 지질과산화작용을 야기함으로써 세포막을 파괴 하고 최종적으로 세포를 사멸시킨다 (Barceló et al., 1988;Jung et al., 2015Jung et al., , 2016Lagriffoul et al., 1998;. 특히 카드뮴에 의해 발생된 산화적 스트레스는 활성산소종의 세포 내 축 적으로 인하여 탄수화물, 단백질, 지질 및 핵산의 생합성에 부정적인 영향을 미치고 산화 ․ 환원 항상성을 교란하여 정 상적인 생체 기능을 저해한다 (Gayomba et al., 2013;Singh and Agrawal, 2010;Singh et al., 2006, Xu et al., 2014. (Fig. 2). 이상의 결과에 근거하여, 벼 뿌리 및 잎으로의 카드뮴전이에 P의 시용효과가 확인되었다. 뿌리에서 16% 감소를 나타냈고, 특히 지상 부인 잎으로의 전이를 44% 감소시킴으로써 전반적인 카드뮴독성을 완화시키는 것으로 판단된다 (Jiang et al., 2007;Mishra et al., 2014;Sajwan et al., 2002). Table 1. Effects of the application of phosphorus (P) on the plant growth characteristics in rice plants grown in the 30 µM cadmium (Cd)-treated hydroponics ...

Phosphorus Regulates the Level of Signaling Molecules in Rice to Reduce Cadmium Toxicity

“…Antioxidant enzymes in plant cells scavenge the reactive oxygen species, protecting the plant from damage [ 24 ]. Rice treated with Cd will have a higher concentration of reactive oxygen such as H 2 O 2 and O 2− , as well as increased activity of antioxidant enzymes such as SOD, POD, and CAT [ 25 , 26 ]. In cadmium-toxic plants, phosphorus has an irregular effect on antioxidant enzyme activity.…”

“…In cadmium-toxic plants, phosphorus has an irregular effect on antioxidant enzyme activity. In Juan’s study, phosphorus treatment increased rice ASA but not GSH [ 25 ]. By contrast, Dai’s study established that increasing the phosphorus treatment significantly increased the GSH content of mangrove seedlings [ 21 ].…”