Plant growth regulators mitigate oxidative damage to rice seedling roots by NaCl stress

PeerJ. 2024 Mar 14:12:e17068. doi: 10.7717/peerj.17068. eCollection 2024.

Abstract

The aim of this experiment was to investigate the effects of exogenous sprays of 5-aminolevulinic acid (5-ALA) and 2-Diethylaminoethyl hexanoate (DTA-6) on the growth and salt tolerance of rice (Oryza sativa L.) seedlings. This study was conducted in a solar greenhouse at Guangdong Ocean University, where 'Huanghuazhan' was selected as the test material, and 40 mg/L 5-ALA and 30 mg/L DTA-6 were applied as foliar sprays at the three-leaf-one-heart stage of rice, followed by treatment with 0.3% NaCl (W/W) 24 h later. A total of six treatments were set up as follows: (1) CK: control, (2) A: 40 mg⋅ L-1 5-ALA, (3) D: 30 mg⋅ L-1 DTA-6, (4) S: 0.3% NaCl, (5) AS: 40 mg⋅ L-1 5-ALA + 0.3% NaCl, and (6) DS: 30 mg⋅ L-1 DTA-6+0.3% NaCl. Samples were taken at 1, 4, 7, 10, and 13 d after NaCl treatment to determine the morphology and physiological and biochemical indices of rice roots. The results showed that NaCl stress significantly inhibited rice growth; disrupted the antioxidant system; increased the rates of malondialdehyde, hydrogen peroxide, and superoxide anion production; and affected the content of related hormones. Malondialdehyde content, hydrogen peroxide content, and superoxide anion production rate significantly increased from 12.57% to 21.82%, 18.12% to 63.10%, and 7.17% to 56.20%, respectively, in the S treatment group compared to the CK group. Under salt stress, foliar sprays of both 5-ALA and DTA-6 increased antioxidant enzyme activities and osmoregulatory substance content; expanded non-enzymatic antioxidant AsA and GSH content; reduced reactive oxygen species (ROS) accumulation; lowered malondialdehyde content; increased endogenous hormones GA3, JA, IAA, SA, and ZR content; and lowered ABA content in the rice root system. The MDA, H2O2, and O2- contents were reduced from 35.64% to 56.92%, 22.30% to 53.47%, and 7.06% to 20.01%, respectively, in the AS treatment group compared with the S treatment group. In the DS treatment group, the MDA, H2O2, and O2- contents were reduced from 24.60% to 51.09%, 12.14% to 59.05%, and 12.70% to 45.20%. In summary, NaCl stress exerted an inhibitory effect on the rice root system, both foliar sprays of 5-ALA and DTA-6 alleviated damage from NaCl stress on the rice root system, and the effect of 5-ALA was better than that of DTA-6.

Keywords: 5-ALA; DTA-6; Keywords Rice root system; NaCl stress; Physiological properties; Rice root system.

MeSH terms

  • Antioxidants* / metabolism
  • Hormones / pharmacology
  • Humans
  • Hydrogen Peroxide / pharmacology
  • Malondialdehyde / pharmacology
  • Oryza*
  • Oxidative Stress
  • Oxygen / pharmacology
  • Plant Growth Regulators / pharmacology
  • Seedlings
  • Sodium Chloride / pharmacology
  • Superoxides / pharmacology

Substances

  • Antioxidants
  • Plant Growth Regulators
  • Hydrogen Peroxide
  • Sodium Chloride
  • Superoxides
  • Oxygen
  • Hormones
  • Malondialdehyde

Grants and funding

This work was supported by program for the Scientific Research Start-up funds of Guangdong Ocean University (060302052010), the Innovation Team Project of ordinary colleges of the Educational Commission of Guangdong Province (2021KCXTD011), the Research start-up project of Guangdong Ocean University (R20046), and the Research start-up project of Guangdong Ocean University (060302052012). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.