Mechanism of Hydrogen Sulfide, a Signaling Molecule Involved in Reducing the Inhibitory Effect of Aluminum Toxicity on Rice Growth Together with Sulfur Fertilizer

doi:10.16819/j.1001-7216.2024.230910

Abstract

Abstract:

【Objectives】The objective of this study was to explore the cultivation method and internal mechanism of alleviating aluminum (Al) toxicity in acidic soil by increasing hydrogen sulfide (H₂S) production in rice through sulfur fertilizer application. 【Methods】With the Al-sensitive rice cultivar kasalath as material, six pot experiment treatments were employed: CK (control), CK+S (sulfur fertilizer application), CK+NaHS (H₂S donor), Al (aluminum treatment), Al+S, and Al+NaHS. The study measured rice internal H₂S content, Al content, antioxidant system enzyme activities at different growth stages, and the indexes related to root growth and photosynthesis during the tillering stage to explore the mechanism of sulfur fertilizer in alleviating the inhibitory effect of Al toxicity on rice growth via an H₂S-dependent pathway. 【Results】Compared to the Al treatment, the Al+S treatment significantly increased the H₂S content in rice. Specifically, it increased by 19.27% and 34.99% at the tillering and full heading stages in rice leaves, and by 39.72%, 21.08%, and 30.73% at the tillering, full heading, and mature stages in rice roots. Additionally, the Al+S treatment significantly enhanced rice root growth and photosynthesis ability at the tillering stage, while decreasing Al content in rice root, shoot, and leaves at different stages. Specifically, it decreased by 40.98%, 28.47%, and 24.18% at the tillering stage, by 14.58%, 50.30%, and 13.17% at the full heading stage, and by 14.44%, 29.78%, and 8.70% at the mature period. Further studies showed that the Al+S treatment significantly enhanced the activity of antioxidant enzymes (SOD, CAT, APX, POD), reduced the content of hydrogen peroxide (H₂O₂), malondialdehyde (MDA), and superoxide anion (O₂⁻·) content in rice, increased the relative expression levels of OsALS1 (related to cytoplasmic Al compartmentalization in vacuoles), and increased the relative expression levels of OsSTAR1 and OsSTAR2 (related to cell wall repair damaged by Al). Additionally, the treatment of Al+NaHS displayed similar effects. 【Conclusions】 The application of exogenous sulfur fertilizer increased internal H₂S content, alleviating the inhibition to rice root growth and photosynthesis induced by Al toxicity. It also increased antioxidant activity, thereby reducing peroxidation damage induced by Al toxicity and decreasing Al content. Furthermore, exogenous sulfur fertilizer application facilitated cytoplasmic Al compartmentalization in vacuoles, reduced cell wall Al deposition, and altered Al form in the rice rhizosphere, thus reducing Al uptake in rice and mitigating growth inhibition induced by Al toxicity.

Key words: aluminum stress, potassium sulfate, hydrogen sulfide, antioxidant enzyme system, rice

摘要：

【目的】究基于施硫肥提高水稻体内硫化氢(H₂S)生成缓解水稻在酸性土壤中铝(Al)毒害的栽培方式及其内在机制。【方法】以Al敏感品种Kasalath为试验材料，设置CK，CK+S(硫肥)，CK+NaHS(H₂S供体)，Al，Al+S，Al+NaHS六个盆栽处理，通过测定不同时期水稻体内H₂S含量、Al含量、抗氧化系统酶活性，分蘖期根系和光合作用相关指标，明确外源施加硫肥通过调控水稻体内H₂S生成缓解Al毒的机制。 【结果】 与Al处理相比，Al+S处理显著提高水稻体内H₂S含量，叶片中的H₂S含量在分蘖期和齐穗期分别增加了19.27%和34.99%；根部H₂S含量在分蘖期、齐穗期和成熟期分别增加了39.72%、21.08%和30.73%。相比Al处理，Al+S处理显著促进了分蘖期水稻根系的生长，提高了水稻的光合作用能力，同时降低了不同时期水稻根茎叶中的Al含量，在分蘖期分别下降了40.98%、28.47%和24.18%；齐穗期下降了14.58%、50.30%和13.17%；成熟期下降了14.44%、29.78%和8.70%。进一步研究发现，Al+S处理显著增强了水稻体内抗氧化酶(SOD、CAT、APX、POD)的活性，降低了水稻体内过氧化氢(H₂O₂)、丙二醛(MDA)、超氧阴离子(O₂⁻·)含量，增加了与细胞质Al在液泡中进行分室相关的基因OsALS1以及与修复被Al破坏的细胞壁相关基因OsSTAR1和OsSTAR2的相对表达量。同时，外源施加硫肥还通过调控土壤pH值降低水稻根际土中交换态Al、无机吸附态Al和水溶态Al的含量，增加Al的水合物和氢氧化物的含量。Al+NaHS处理具有同样的效果。【结论】 外源增施硫肥能够通过提高水稻体内的H₂S含量缓解Al对水稻根系生长和光合作用的抑制，提高抗氧化系统酶活性降低Al对水稻的过氧化损伤，同时促进液泡对水稻细胞质Al的区室化作用，降低细胞壁对Al的吸附或改变土壤中Al的形态，最终降低水稻根系内的Al含量来缓解Al对水稻生长的抑制作用。

关键词: 铝胁迫, 硫酸钾, 硫化氢, 抗氧化酶系统, 水稻

WEI Qianqian, WANG Yulei, KONG Haimin, XU Qingshan, YAN Yulian, PAN Lin, CHI Chunxin, KONG Yali, TIAN Wenhao, ZHU Lianfeng, CAO Xiaochuang, ZHANG Junhua, ZHU Chunqun. Mechanism of Hydrogen Sulfide, a Signaling Molecule Involved in Reducing the Inhibitory Effect of Aluminum Toxicity on Rice Growth Together with Sulfur Fertilizer[J]. Chinese Journal OF Rice Science, 2024, 38(3): 290-302.

魏倩倩, 汪玉磊, 孔海民, 徐青山, 颜玉莲, 潘林, 迟春欣, 孔亚丽, 田文昊, 朱练峰, 曹小闯, 张均华, 朱春权. 信号分子硫化氢参与硫肥缓解铝对水稻生长抑制作用的机制[J]. 中国水稻科学, 2024, 38(3): 290-302.

Figures/Tables 10

Table 1. Primers selected for this study and their sequences

基因Gene	序列Sequence (5′-3′)
OsHistone-R	AACCGCAAAATCCAAAGAACG
OsHistone-F	GGTCAACTTGTTGATTCCCCTCT
OsALS1-F	GGTCGTCAGTCTCTGCCTTCTCO
OsALS1-R	CCTCCCCATCATTTTCATTTGT
OsSTAR1-F	TCGCATTGGCTCGCACCCT
OsSTAR1-R	TCGTCTTCTTCAGCCGCACGAT
OsSTAR2-F	ACCTCTTCATGGTCACCGTCG
OsSTAR2-R	CCTCAGCTTCTTCATCGTCACC

Fig. 1. Changes of H2S content in rice under different treatments Different letters in the figure mean significant difference in the results by the analysis of variance (P<0.05), and the values are mean ± standard deviation (n=3). TS, Tillering stage; HS, Full heading stage; MS, Mature stage. CK, 0.12 g/kg KCl; CK+S, KCl was replaced by 0.12 g/kg K2SO4；CK+NaHS, 0.12 g/kg KCl; 10 mL 10 μmol/L NaHS per week, Al, 2.5 g/kg AlCl3 was mixed with soil; 0.12 g/kg KCl, Al+S: 2.5 g/kg AlCl3 was mixed with soil; KCl was replaced by 0.12 g/kg K2SO4; Al+NaHS, 2.5 g/kg AlCl3 + 0.12 g/kg KCl(mixed with soil); 10 mL 10 μmol/L NaHS was applied per week. The same below.

Table 2. Effects of S fertilizer application on rice root growth

处理 Treatment	根总长 Total root length(cm)	根平均直径 Average root diameter(mm)	根总面积 Total root area(cm²)	根总体积 Total volume of roots(cm³)	根尖计数 Total root tip counts
CK	5326.61±67.90 b	1.48±0.16 a	1779.40±80.11 b	49.37±7.015 b	33449±412 ab
CK+S	5363.48±7.31 b	1.37±0.16 ab	1775.80±81.29 b	53.21±3.95 b	29847±603 b
CK+NaHS	5373.04±79.76 b	1.30±0.04 abc	1526.82±93.32 c	43.98±3.56 b	30219±175 b
Al	3356.06±105.96 d	1.06±0.03 c	1052.38±7.75 d	27.03±7.10 c	20640±448 c
Al+S	6107.49±21.07 a	1.17±0.15 bc	2480.62±165.94 a	71.50±7.90 a	35210±4190 a
Al+NaHS	3559.97±139.96 c	1.43±0.06 ab	1779.40±80.11 b	45.27±3.82 b	23117±881 c

Table 3. Effects of S fertilizer application on photosynthetic indexes of rice

处理 Treatment	净光合速率 P_n(µmol·m⁻²s⁻¹)	胞间CO₂浓度 C_i(mmol·mol⁻¹)	蒸腾速率 T_r(μmol·m⁻²s⁻¹)	气孔导度 G_s(μmol·m⁻²s⁻¹)
CK	13.51±0.30 a	325.08±3.55 ab	9.80±0.42 a	384.64±21.84 a
CK+S	13.19±0.87 a	315.18±5.36 bc	9.21±0.70 a	361.63±14.37 b
CK+NaHS	12.98±1.00 a	313.5±0.02 bc	9.50±0.53 a	355.15±6.50 b
Al	6.66±0.13 d	284.75±7.54 c	3.64±0.31 d	223.69±2.11 d
Al+S	8.44±0.05 c	304.69±3.24 b	4.94±0.63 c	251.93±10.34 c
Al+NaHS	12.51±0.06 a	334.13±6.60 a	6.73±1.06 b	356.34±3.11 b

Fig. 2. Effects of S fertilizer application on photosynthetic pigment contents in rice Different letters in the figure mean significant difference in the results by the analysis of variance (P<0.05), and the values are mean ± standard deviation (n=3). TS, Tillering stage.

Fig. 3. Effects of S fertilizer application on Al contents in roots, stems and leaves of rice at different growth stages Different letters in the figure mean significant difference in the results by the analysis of variance (P<0.05), and the values are mean ± standard deviation (n=3). TS, Tillering stage; HS, Full heading stage; MS, Mature stage.

Fig. 4. Effects of S application on the changes of Al form and pH in rhizosphere soil Different letters in the figure mean significant difference in the results by the analysis of variance (p<0.05), and the values are mean ± standard deviation (n=3). TS, Tillering stage, HS, Full heading stage, MS, Mature stage. Alw，Water soluble aluminum; Alo, Organic combined aluminum; Alh, Humic acid aluminum; Aloh，Aluminum of hydrous oxide and hydroxide; Alino, Inorganic adsorption aluminum; Alex, Exchangeable aluminum.

Fig. 5. Effects of S fertilizer application on contents of O2−·, MDA and H2O2 in roots and leaves of rice at different growth stages Different letters in the figure indicate significant difference in the results by the analysis of variance (P<0.05), and the values are mean ± standard deviation (n=3). TS, Tillering stage; HS, Full heading stage; MS, Mature stage.

Fig. 6. Effects of S fertilizer on the activities of antioxidant enzymes in root and leaf of rice at different growth stages Different letters in the figure indicate significant difference in the results by the analysis of variance (P<0.05), and the values are mean ± standard deviation (n=3). TS, Tillering stage, HS, Full heading stage, MS, Mature stage.

Fig. 7. Effects of exogenous application of S fertilizer on the relative expression levels of OsALS1, OsSTAR1 and OsSTAR2 in rice at different growth stages Different letters indicate significant difference by the analysis of variance (P<0.05), and the values are mean ± standard deviation (n=3). TS, Tillering stage; HS, Full heading stage; MS, Mature stage.

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