Manganese Repairs the Oxygen-Evolving Complex (OEC) in Maize ( Zea mays L.) Damage During Seawater Vulnerability
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ORIGINAL PAPER
Manganese Repairs the Oxygen-Evolving Complex (OEC) in Maize (Zea mays L.) Damage During Seawater Vulnerability Ramwant Gupta 1 Received: 14 October 2019 / Accepted: 2 March 2020 # Sociedad Chilena de la Ciencia del Suelo 2020
Abstract This study was aimed to investigate how exogenous manganese (Mn) would limit damage in the oxygen-evolving complex (OEC) and photosynthetic apparatus of maize seedlings caused during seawater vulnerability. In this study, seawater was applied in 2-week-old maize (Zea mays L.) seedling, and the degree of damage of photosynthetic pigment pool, the OEC, and net electron transport rate were observed. Mn supplement was also added in maize seedlings to limit the damage of the OEC and photosynthetic apparatus caused during salinity. Leaf relative water content (RWC), fresh weight (FW), and photosynthetic pigment pool (chlorophyll a, chlorophyll b, and carotenoids) sharply declined after 7 days of treatment; however, Mn supplement increased these values. Chlorophyll fluorescence induction (OJIP) transients showed low Fv/Fo, an additional K step, enhanced variable fluorescence (VK) and degree of damage to the OEC (WK) during salinity, and indicates damage of OEC at electron donor side of photosystem II (PSII). The OEC intact within PSII was a primary damage center during salinity which inhibited electron transport process that resulted in a huge loss of maximum quantum yield of PSII (Fv/Fm), but a significant recovery in photosynthetic apparatus was observed after exogenous application of manganese. Structural and functional integrity of the photosynthetic apparatus was recovered up to a certain extent after exogenous application of Mn. Findings from this study should help to understand the basic knowledge of photosynthetic apparatus efficiency in response to damage caused by exposure to seawater. Outcomes of this study will be used to mitigate salinity problem with Mn supplement for growth and development of crops. Keywords Salinity . Oxygen-evolving complex (OEC) . Mn . Photosynthetic apparatus . Maize
1 Introduction Maize (Zea mays L.) is a primary cereal crop and important for global food security. Salinity is one of the major abiotic stresses that overwhelmed crop performance especially in arid and semiarid regions and has affected 6% of the total land areas of the world (Munns and Tester 2008; Godfray et al. 2011; Foley et al. 2011; Wu and Guclu 2013). Salt concentration and electrical conductivity in affected lands are close to seawater (Shannon 1998). It is assumed that the salt-affected area of cultivated lands will increase by over 40% by 2050 (Mahajan and Tuteja 2005). The negative impacts on plants of salinity
* Ramwant Gupta [email protected]; [email protected] 1
Department of Biology, School of Pure Sciences, College of Engineering Science and Technology, Fiji National University, PO Box 5529, Natabua, Suva, Fiji
begin with lowering the osmotic potential of soil that reduces water uptake and ends up with an increase in the concentration of certa
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