Assessment of selenium spatial distribution using mu-XFR in cowpea (Vigna unguiculata (L.) Walp.) plants: Integration of physiological and biochemical responses

Author(s)

Lanza, Maria Gabriela Dantas Bereta ^[1] ; Silva, Vinicius Martins ^[1] ; Montanha, Gabriel Sgarbiero ^[2] ; Lavres, Jose ^[2] ; de Carvalho, Hudson Wallace Pereira ^[2] ; dos Reis, Andre Rodrigues ^{[3, 1]}

Affiliation

^[1] Sao Paulo State Univ UNESP, Via Acesso Prof Paulo Donato Castellane S-N, BR-14884900 Jaboticabal, SP - Brazil

^[2] Univ Sao Paulo, Ave Centenario, 303, BR-13400970 Piracicaba, SP - Brazil

^[3] Sao Paulo State Univ UNESP, Rua Domingos Costa Lopes 780, BR-17602496 Tupa, SP - Brazil

• Document type: Journal article
• Source: ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY; v. 207, JAN 1 2021.
• Web of Science Citations: 0

Abstract

Low concentrations of selenium (Se) are beneficial for plant growth. Foliar Se application at high concentrations is toxic to plants due to the formation of reactive oxygen species (ROS). This study characterized Se toxicity symptoms using X-ray fluorescence (XRF) technique in response to foliar Se application in cowpea plants. Five Se concentrations (0, 10, 25, 50, 100 e 150 g ha(-1)) were sprayed on leaves as sodium selenate. The visual symptoms of Se toxicity in cowpea leaves were separated into two stages: I) necrotic points with an irregular distribution and internerval chlorosis at the leaf limb border (50-100 g ha(-1)); II) total chlorosis with the formation of dark brown necrotic lesions (150 g ha(-1)). Foliar Se application at 50 g ha(-1) increased photosynthetic pigments and yield. Ultrastructural analyses showed that Se foliar application above 50 g ha(-1) disarranged the upper epidermis of cowpea leaves. Furthermore, Se application above 100 g ha(-1) significantly increased the hydrogen peroxide concentration and lipid peroxidation inducing necrotic leaf lesions. Mapping of the elements in leaves using the XRF revealed high Se intensity, specifically in leaf necrotic lesions accompanied by calcium (Ca) as a possible attenuating mechanism of plant stress. The distribution of Se intensities in the seeds was homogeneous, without specific accumulation sites. Phosphorus (P) and sulfur (S) were found primarily located in the embryonic region. Understanding the factors involved in Se accumulation and its interaction with Ca support new preventive measurement technologies to prevent Se toxicity in plants. (AU)

• FAPESP's process: 15/26817-9 - Selenium application forms in cowpea plants aiming agronomic biofortification and improvement of bean nutritional quality
• Grantee: Maria Gabriela Dantas Bereta Lanza
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• FAPESP's process: 18/15490-7 - Evaluation of ureide metabolism and nitrogen compounds in cowpea plants in response to selenium application and its relation to grain nutritional quality
• Grantee: Maria Gabriela Dantas Bereta Lanza
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• FAPESP's process: 15/19121-8 - Multi-User Equipment approved in grant 2015/05942-0: micro X-Ray Fluorescence system
• Grantee: Hudson Wallace Pereira de Carvalho
• Support Opportunities: Multi-user Equipment Program
• FAPESP's process: 15/05942-0 - Shedding light on the metabolism of nanomaterials absorbed by plants with X-ray and vibrational spectroscopy
• Grantee: Hudson Wallace Pereira de Carvalho
• Support Opportunities: Research Grants - Young Investigators Grants