Functional Analysis of Organic Acids on Different Oilseed Rape Species in Phytoremediation of Cadmium Pollution.

Shi Li,Rui Wang,Yun Zhao,Sixiu Le,Jiuyuan Bai,Xin Wang

doi:10.3390/plants9070884

Abstract

Cadmium (Cd) pollution in soil is becoming increasingly serious due to anthropogenic activities, which not only poses a threat to the ecological environment, but also causes serious damage to human health via the biological chain. Consequently, special concerns should be paid to develop and combine multiple remediation strategies. In this study, different subspecies of oilseed rape, Brassica campestris, Brassica napus and Brassica juncea were applied, combined with three organic acids, acetic acid, oxalic acid and citric acid, in a simulated Cd-contaminated soil. Various physiological and biochemical indexes were monitored in both plant seedling, growth period and mature stage. The results showed that organic acids significantly promoted the growth of Brassica campestris and Brassica juncea under Cd stress. The photosynthesis and antioxidant enzyme activities in Brassica campestris and Brassica juncea were induced at seedling stage, while that in Brassica napus were suppressed and disturbed. The enrichment of Cd in oilseed rape was also obviously increased. Brassica juncea contained relatively high resistance and Cd content in plant but little Cd in seed. Among the three acids, oxalic acids exhibited the most efficient promoting effect on the accumulation of Cd by oilseed rape. Here, a comprehensive study on the combined effects of oilseed rape and organic acids on Cd contaminated soil showed that Brassica juncea and oxalic acid possessed the best effect on phytoremediation of Cd contaminated soil. Our study provides an optimal way of co-utilizing oilseed rape and organic acid in phytoremediation of Cd contaminated soil.

Highlights

Soil pollution is becoming increasingly fierce with the development of industry, agriculture and urbanization on a global scale
In the absence of organic acid treatment (Control), the plant DW in Brassica campestris and Brassica juncea was apparently higher than Brassica napus, which indicated a stronger growth capacity and higher biomass in the two varieties
Compared with Brassica campestris and Brassica juncea, three organic acids all could greatly increase plant dry weight in Brassica campestris, while only oxalic acid held the capacity to significantly enhance both two indexes in Brassica juncea, in which the root dry weight and plant height were notably increased by each organic acid

Summary

Introduction

Soil pollution is becoming increasingly fierce with the development of industry, agriculture and urbanization on a global scale. Inorganic contaminants (mainly heavy metals, HMs) concentrated in soil has aroused major concerns in line with a growing number of reports about heavy metal pollution emerged in an endless stream. 82.8% soil contamination is caused by inorganic contaminants in China while 34.8% present in soil and groundwater in Europe [1,2]. Compared with diverse soil heavy metal pollution elements, cadmium (Cd) is the most serious one and contributes 7%. To the HMs contaminated soil in China [3]. Cd is generally considered as a kind of highly mobile, toxic, absorbed elements by plants and is difficult to degrade [4,5]. It is commonly understood that Cd is not an essential element and does not have any physiological function in plants. Even excessive Cd in plants destroys the structure of plant cells, but it disturbs the normal physiological process, Plants 2020, 9, 884; doi:10.3390/plants9070884 www.mdpi.com/journal/plants

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Conclusion