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Chen H, Liang X, Gong X, Reinfelder JR, Chen H, Sun C, Liu X, Zhang S, Li F, Liu C, Zhao J, Yi J. Comparative physiological and transcriptomic analyses illuminate common mechanisms by which silicon alleviates cadmium and arsenic toxicity in rice seedlings. J Environ Sci (China) 2021; 109:88-101. [PMID: 34607677 DOI: 10.1016/j.jes.2021.02.030] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2021] [Revised: 02/27/2021] [Accepted: 02/28/2021] [Indexed: 06/13/2023]
Abstract
The inessential heavy metal/loids cadmium (Cd) and arsenic (As), which often co-occur in polluted paddy soils, are toxic to rice. Silicon (Si) treatment is known to reduce Cd and As toxicity in rice plants. To better understand the shared mechanisms by which Si alleviates Cd and As stress, rice seedlings were hydroponically exposed to Cd or As, then treated with Si. The addition of Si significantly ameliorated the inhibitory effects of Cd and As on rice seedling growth. Si supplementation decreased Cd and As translocation from roots to shoots, and significantly reduced Cd- and As-induced reactive oxygen species generation in rice seedlings. Transcriptomics analyses were conducted to elucidate molecular mechanisms underlying the Si-mediated response to Cd or As stress in rice. The expression patterns of the differentially expressed genes in Cd- or As-stressed rice roots with and without Si application were compared. The transcriptomes of the Cd- and As-stressed rice roots were similarly and profoundly reshaped by Si application, suggesting that Si may play a fundamental, active role in plant defense against heavy metal/loid stresses by modulating whole genome expression. We also identified two novel genes, Os01g0524500 and Os06g0514800, encoding a myeloblastosis (MYB) transcription factor and a thionin, respectively, which may be candidate targets for Si to alleviate Cd and As stress in rice, as well as for the generation of Cd- and/or As-resistant plants. This study provides valuable resources for further clarification of the shared molecular mechanisms underlying the Si-mediated alleviation of Cd and As toxicity in rice.
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Affiliation(s)
- Huiqiong Chen
- College of Life Sciences, South China Agricultural University, Guangzhou 510642, China
| | - Xiaoyu Liang
- College of Life Sciences, South China Agricultural University, Guangzhou 510642, China
| | - Xiaomei Gong
- College of Life Sciences, South China Agricultural University, Guangzhou 510642, China
| | - John R Reinfelder
- Department of Environmental Sciences, Rutgers University, New Brunswick, NJ 08901, USA
| | - Huamei Chen
- College of Life Sciences, South China Agricultural University, Guangzhou 510642, China
| | - Chongjun Sun
- College of Life Sciences, South China Agricultural University, Guangzhou 510642, China
| | - Xiulian Liu
- College of Life Sciences, South China Agricultural University, Guangzhou 510642, China
| | - Shuchang Zhang
- College of Life Sciences, South China Agricultural University, Guangzhou 510642, China
| | - Fangbai Li
- Guangdong Institute of Eco-environmental Science & Technology, Guangzhou 510650, China
| | - Chuanping Liu
- Guangdong Institute of Eco-environmental Science & Technology, Guangzhou 510650, China
| | - Junliang Zhao
- Rice Research Institute & Guangdong Key Laboratory of New Technology in Rice Breeding, Guangdong Academy of Agricultural Sciences, Guangzhou 510640, China.
| | - Jicai Yi
- College of Life Sciences, South China Agricultural University, Guangzhou 510642, China.
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Oard SV. Deciphering a mechanism of membrane permeabilization by α-hordothionin peptide. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2011; 1808:1737-45. [PMID: 21315063 DOI: 10.1016/j.bbamem.2011.02.003] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/27/2010] [Revised: 01/19/2011] [Accepted: 02/01/2011] [Indexed: 11/19/2022]
Abstract
α-Hordothionin (αHTH) belongs to thionins, the plant antimicrobial peptides with membrane-permeabilizing activity which is associated with broad-range antimicrobial activity. Experimental data have revealed a phospholipid-binding site and indicated formation of ion channels as well as membrane disruption activity of thionin. However, the mechanism of membrane permeabilization by thionin remained unknown. Here it is shown that thionin is a small water-selective channel. Unbiased high-precision molecular modeling revealed formation of a water-selective pore running through the αHTH double α-helix core when the peptide interacted with anions. Anion-induced unfolding of the C-end of the α2-helix opened a pore mouth. The pore started at the α2 C-end between the hydrophilic and the hydrophobic regions of the peptide surface and ended in the middle of the unique hydrophobic region at the C-end of the α1-helix. Highly conserved residues including cysteines and tyrosine lined the pore walls. A large positive electrostatic potential accumulated inside the pore. The narrow pore was, nonetheless, sufficient to accommodate at least one water molecule along the channel except for two constriction sites. Both constriction sites were formed by residues participating in the phospholipid-binding site. The channel properties resembled that of aquaporins with two selectivity filters, one at the entrance, inside the α2 C-end cavity, and a second in the middle of the channel. It is proposed that the αHTH water channel delivers water molecules to the bilayer center that leads to local membrane disruption. The proposed mechanism of membrane permeabilization by thionins explains seemingly controversial experimental data.
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Affiliation(s)
- Svetlana V Oard
- School of Plant, Environmental, and Soil Sciences, Louisiana State Agricultural Center, Louisiana State University, Baton Rouge, LA 70803, USA.
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