Key message Overexpression of the Ni2+-dependent glyoxalase I genes AtGLYI3 and AtGLYI6 enhances nickel stress tolerance in Arabidopsis. The transgenic lines exhibit reduced reactive oxygen species accumulation under nickel stress, indicating improved oxidative stress management and contributing to enhanced nickel tolerance. Abstract This study investigated the role of Ni2+-dependent glyoxalase I (GLYI) in nickel stress tolerance in the model plant Arabidopsis thaliana. A comparative analysis was conducted among wild-type, GLYI mutants (glyI-2, glyI-3, glyI-6), Zn2⁺ dependent (AtGLYI2_OE-1), and Ni2⁺ dependent (AtGLYI3_OE, AtGLYI6_OE) GLYI gene-overexpressing transgenic lines to elucidate the biochemical and phenotypic responses. Under 200 µM NiCl₂, AtGLYI3_OE and AtGLYI6_OE exhibited higher germination and enhanced root growth compared with wild-type, mutants, and AtGLYI2_OE-1, particularly in the presence of GA, SA, and IAA. Under severe nickel toxicity (20 mM NiCl₂), wild-type and AtGLYI2_OE-1 showed greater sensitivity, as indicated by reduced chlorophyll content and antioxidant activity, along with elevated MDA, d-lactate, and ROS levels, whereas AtGLYI3_OE and AtGLYI6_OE demonstrated improved tolerance. ICP-MS analysis revealed lower Ni2⁺ accumulation in glyI-2 than glyI-3 mutants, underscoring the importance of Ni2⁺-dependent AtGLYI3 in stress mitigation. Collectively, these results indicate that Ni2⁺-dependent GLYI plays a predominant role in nickel tolerance, whereas Zn2⁺-dependent GLYI is mainly involved in methylglyoxal detoxification. Subsequently, LC–MS/MS analysis revealed the lowest Salicylic acid (SA) in mutants, followed by all GLYI-overexpressing lines, compared to wild-type, indicating a potential link between GLYI activity and SA homeostasis. Further, exogenous SA enhanced recovery in AtGLYI3_OE and AtGLYI6_OE under Ni2⁺ stress, with minimal effects on wild type and mutants, indicating a complementary role of SA in Ni2⁺-dependent GLYI. Additionally, increased bZIP2 and NRT1.1 expression was observed in Ni2⁺-dependent GLYI transgenic lines under NiCl₂ stress. Therefore, future studies are needed to find potential links between Ni2⁺-dependent GLYI with SA/GA biosynthesis and nitrogen-related stress responses. Graphical abstract

AtGLYI3 and AtGLYI6 play the major role in nickel stress tolerance in Arabidopsis thaliana

期刊论文
发表日期：

2026年6月19日

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Nazmir Binta Alam,
Rituraj Batth,
Abdullah Al Mohit,
Chokey Lhamo,
Ananda Mustafiz

摘要

Key message

Overexpression of the Ni²⁺-dependent glyoxalase I genes AtGLYI3 and AtGLYI6 enhances nickel stress tolerance in Arabidopsis. The transgenic lines exhibit reduced reactive oxygen species accumulation under nickel stress, indicating improved oxidative stress management and contributing to enhanced nickel tolerance.

Abstract

This study investigated the role of Ni²⁺-dependent glyoxalase I (GLYI) in nickel stress tolerance in the model plant Arabidopsis thaliana. A comparative analysis was conducted among wild-type, GLYI mutants (glyI-2, glyI-3, glyI-6), Zn²⁺ dependent (AtGLYI2_OE-1), and Ni²⁺ dependent (AtGLYI3_OE, AtGLYI6_OE) GLYI gene-overexpressing transgenic lines to elucidate the biochemical and phenotypic responses. Under 200 µM NiCl₂, AtGLYI3_OE and AtGLYI6_OE exhibited higher germination and enhanced root growth compared with wild-type, mutants, and AtGLYI2_OE-1, particularly in the presence of GA, SA, and IAA. Under severe nickel toxicity (20 mM NiCl₂), wild-type and AtGLYI2_OE-1 showed greater sensitivity, as indicated by reduced chlorophyll content and antioxidant activity, along with elevated MDA, d-lactate, and ROS levels, whereas AtGLYI3_OE and AtGLYI6_OE demonstrated improved tolerance. ICP-MS analysis revealed lower Ni²⁺ accumulation in glyI-2 than glyI-3 mutants, underscoring the importance of Ni²⁺-dependent AtGLYI3 in stress mitigation. Collectively, these results indicate that Ni²⁺-dependent GLYI plays a predominant role in nickel tolerance, whereas Zn²⁺-dependent GLYI is mainly involved in methylglyoxal detoxification. Subsequently, LC–MS/MS analysis revealed the lowest Salicylic acid (SA) in mutants, followed by all GLYI-overexpressing lines, compared to wild-type, indicating a potential link between GLYI activity and SA homeostasis. Further, exogenous SA enhanced recovery in AtGLYI3_OE and AtGLYI6_OE under Ni²⁺ stress, with minimal effects on wild type and mutants, indicating a complementary role of SA in Ni²⁺-dependent GLYI. Additionally, increased bZIP2 and NRT1.1 expression was observed in Ni²⁺-dependent GLYI transgenic lines under NiCl₂ stress. Therefore, future studies are needed to find potential links between Ni²⁺-dependent GLYI with SA/GA biosynthesis and nitrogen-related stress responses.

Graphical abstract