Mechanism enhancing arabidopsis resistance to cadmium: The role of NRT1.5 and proton pump

Tao Wang, Yingpeng Hua, Moxian Chen, Jianhua ZHANG, Chunyun Guan, Zhenhua Zhang*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

7 Citations (Scopus)

Abstract

Aim: Heavy metal pollution is serious in China, and abscisic acid (ABA) is an important stress hormone. How it regulates plant tolerance to cadmium remains unclear, so we aimed to explore the molecular mechanism responsible for enhanced cadmium resistance in Arabidopsis wild-type and mutant plants and Brassica napus seedlings. Methods: Arabidopsis/B. napus were cultured hydroponically for 28/15 days and then treated with 20/10 μM Cd/Cd+ABA (5 μM) for 3/4 days. Chlorophyll degradation rate, SPAD values, proline, MDA, ABA, (Formula presented.), and Cd concentrations were measured in root vacuoles and protoplasts; root to shoot (Formula presented.) and Cd concentration ratios were determined and NRT1.5-, NRT1.8-, BnNRT1.5-, and BnNRT1.8-related gene expression was studied. Results: Cytoplasmic ABA levels in root cells of bglu10 and bglu18 Arabidopsis mutants were significantly lower than those in the wild-type, apparently making the latter more resistant to Cd. (Formula presented.) long-distance transporter NRT1.5 responded to ABA signaling by downregulating its own expression, while NRT1.8 did not respond. Concomitantly, proton pump activity in wild-type plants was higher than in the bglu10 and bglu18 mutants; thus, more (Formula presented.) and Cd accumulated in the vacuoles of wild-type root cells. ABA application inhibited Cd absorption by B. napus. BnNRT1.5 responded to exogenous ABA signal by downregulating its own expression, while the lack of response by BnNRT1.8 resulted in increased amount of (Formula presented.) accumulating in the roots to participate in the anti-cadmium reaction. Conclusion: NRT1.5 responds to the ABA signal to inhibit its own expression, whereas unresponsiveness of NRT1.8 causes accumulation of (Formula presented.) in the roots; thus, enhancing Cd resistance. In Arabidopsis, because of proton pump action, more (Formula presented.) and Cd accumulate in the vacuoles of Arabidopsis root cells, thereby reducing damage by Cd toxicity. However, in B. napus, the addition of exogenous ABA inhibited Cd absorption. Our data provide a sound basis to the theoretical molecular mechanism involved in hormone signaling during response of plants to heavy metal stress.

Original languageEnglish
Article number1892
JournalFrontiers in Plant Science
Volume871
DOIs
Publication statusPublished - 2018

Scopus Subject Areas

  • Plant Science

User-Defined Keywords

  • ABA signaling
  • Cd stress
  • NO
  • NRT1.5
  • NRT1.8
  • Proton pump activity

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