Foliar spraying of indoleacetic acid (IAA) enhances the phytostabilization of Pb in naturally tolerant ryegrass by limiting the root-to-shoot transfer of Pb and improving plant growth

Chengqiang Zhu; Runhai Jiang; Shaofu Wen; Tiyuan Xia; Saiyong Zhu; Xiuli Hou

doi:10.7717/peerj.16560

Foliar spraying of indoleacetic acid (IAA) enhances the phytostabilization of Pb in naturally tolerant ryegrass by limiting the root-to-shoot transfer of Pb and improving plant growth

PeerJ. 2023 Dec 15:11:e16560. doi: 10.7717/peerj.16560. eCollection 2023.

Authors

Chengqiang Zhu¹, Runhai Jiang¹, Shaofu Wen¹, Tiyuan Xia¹, Saiyong Zhu^{2

3}, Xiuli Hou¹

Affiliations

¹ Kunming University, Kunming, China.
² Zhejiang Ecological Civilization Academy, Huzhou, China.
³ College of Environmental & Resource Sciences of Zhejiang University, Hangzhou, China.

Abstract

Exogenous addition of IAA has the potential to improve the metal tolerance and phytostabilization of plants, but these effects have not been systematically investigated in naturally tolerant plants. Ryegrass (Lolium perenne L.) is a typical indigenous plant in the Lanping Pb/Zn mining area with high adaptability. This study investigated the phytostabilization ability and Pb tolerance mechanism of ryegrass in response to Pb, with or without foliar spraying of 0.1 mmol L^-1 IAA. The results indicated that appropriate IAA treatment could be used to enhance the phytostabilization efficiency of naturally tolerant plants. Foliar spraying of IAA increased the aboveground and belowground biomass of ryegrass and improved root Pb phytostabilization. Compared to Pb-treated plants without exogenous IAA addition, Pb concentration in the shoots of ryegrass significantly decreased, then increased in the roots after the foliar spraying of IAA. In the 1,000 mg kg^-1 Pb-treated plants, Pb concentration in the shoots decreased by 69.9% and increased by 79.1% in the roots after IAA treatment. IAA improved plant growth, especially in soils with higher Pb concentration. Foliar spraying of IAA increased shoot biomass by 35.9% and root biomass by 109.4% in 1,000 mg kg^-1 Pb-treated plants, and increased shoot biomass by 196.5% and root biomass by 71.5% in 2,000 mg kg^-1 Pb-treated plants. In addition, Pb stress significantly decreased the content of photosynthetic pigments and anti-oxidase activities in ryegrass, while foliar spraying of IAA remedied these negative impacts. In summary, foliar spraying of IAA could increase the biomass and improve the Pb tolerance of ryegrass.

Keywords: Anti-oxidase; Foliar spraying; Heavy metal; IAA; Phytostabilization.

MeSH terms

Biodegradation, Environmental
Lead / toxicity
Lolium*
Soil Pollutants* / analysis

Substances

indoleacetic acid
Lead
Soil Pollutants

Grants and funding

This work was supported by the National Natural Science Foundation of China(42167009, 31300349, U1902202), the Special Project of Basic Research in Yunnan Local Colleges and Universities (2018FH001-004), the International Joint Innovation Team for Yunnan Plateau Lakes and Great Lakes of North America which is sponsored by the Yunnan Provincial Education Department (XC) and the Major Program for Basic Research Project of Yunnan Province(202101BC070002). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.