Reducing phenanthrene uptake and translocation, and accumulation in the seeds by overexpressing OsNRT2.3b in rice

Xiaowen Wang; Ajay Jain; Xu Huang; Xiaoxia Lan; Li Xu; Gengmao Zhao; Xin Cong; Zhantian Zhang; Xiaorong Fan; Feng Hu

doi:10.1016/j.scitotenv.2020.143690

Reducing phenanthrene uptake and translocation, and accumulation in the seeds by overexpressing OsNRT2.3b in rice

Sci Total Environ. 2021 Mar 20:761:143690. doi: 10.1016/j.scitotenv.2020.143690. Epub 2020 Nov 23.

Authors

Xiaowen Wang¹, Ajay Jain², Xu Huang³, Xiaoxia Lan³, Li Xu⁴, Gengmao Zhao⁵, Xin Cong⁶, Zhantian Zhang⁷, Xiaorong Fan³, Feng Hu⁸

Affiliations

¹ Soil Ecology Lab, College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing 210095, China; College of Horticulture, Nanjing Agricultural University, Nanjing 210095, China.
² Amity Institute of Biotechnology, Amity University Rajasthan, Jaipur, India.
³ State Key Laboratory of Crop Genetics and Germplasm Enhancement, Key Laboratory of Plant Nutrition and Fertilization in Low-Middle Reaches of the Yangtze River, Ministry of Agriculture, Nanjing Agricultural University, Nanjing 210095, China.
⁴ Soil Ecology Lab, College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing 210095, China.
⁵ College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing 210095, China.
⁶ College of Horticulture, Nanjing Agricultural University, Nanjing 210095, China.
⁷ Institute of Plant Protection & Resource and Environment, Yantai Academy of Agricultural Sciences, Yantai 265500, China.
⁸ Soil Ecology Lab, College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing 210095, China. Electronic address: fenghu@njau.edu.cn.

PMID: 33348216
DOI: 10.1016/j.scitotenv.2020.143690

Abstract

The uptake and accumulation of polycyclic aromatic hydrocarbons (PAHs) in crops have gained much attention due to their toxicity to humans. Nitrogen (N) is an essential element for plant growth and has also been implicated in the acquisition and acropetal translocation of PAHs. OsNRT2.3b encodes a nitrate (NO₃^-) transporter that is involved in the acquisition and mobilization of N in rice. Here, we investigated whether overexpression of OsNRT2.3b would exert any mitigating influence on the uptake and translocation of phenanthrene (Phe, a model PAH) in transgenic rice (Oryza sativa). The wild-type seedlings exhibited a reduction in plant height, primary root length, and shoot biomass when grown hydroponically in a medium supplemented with Phe. Acquisition of Phe by the roots and its subsequent translocation to shoots increased concomitantly with an increase in Phe concentration in the medium and duration of the treatment. OsNRT2.3b-overexpressing lines (Ox-6 and Ox-8) were generated independently. Compared with the wild-type, the concentration of Phe in Ox-6 and Ox-8 were significantly lower in the roots (47%-54%) and shoots (22%-31%) grown hydroponically with Phe (1 mg/L). Further, the wild-type and Ox lines were grown to maturity in a pot soil under Phe conditions and the concentrations of Phe and total N were assayed in the culms and flag leaves. Compared with the wild-type, in Ox lines the concentration of total N significantly increased in the culms (288%-366%) and flag leaves (12%-25%), while that of Phe significantly reduced in the culms (25%-28%) and flag leaves (18%-21%). The results revealed an antagonistic correlation between the concentration of total N and Phe. The concentration of Phe was also significantly lower (29%-38%) in the seeds of Ox lines than the wild-type. The study highlighted the efficacy of overexpressing OsNRT2.3b in mitigating the Phe toxicity by attenuating its acquisition, mobilization, and allocation to the seeds.

Keywords: Nitrogen; OsNRT2.3b; Phenanthrene; Rice (Oryza sativa); Seed.

MeSH terms

Anion Transport Proteins / genetics
Anion Transport Proteins / metabolism
Gene Expression Regulation, Plant
Humans
Oryza* / genetics
Oryza* / metabolism
Phenanthrenes*
Plant Proteins / metabolism
Plant Roots / metabolism
Seeds / metabolism

Substances

Anion Transport Proteins
Phenanthrenes
Plant Proteins