DFNet

June 7, 2025 | Plant Physiology and Biochemistry |

A study investigating the molecular mechanisms underlying salt tolerance in red pitaya (Hylocereus polyrhizus), a fruit gaining global interest for its nutritional and economic value, was conducted by researchers from the South China Botanical Garden and the Chinese Academy of Sciences, Guangzhou. With soil salinization presenting a challenge to crop cultivation, particularly on islands and in marginal lands, improving pitaya's adaptability to saline environments is a key research priority.

The study focused on the role of oxalate metabolism in pitaya’s salt stress response. While oxalate is traditionally viewed as an antinutrient, it also acts as a signaling molecule in stress regulation. Transcriptomic analysis revealed that salt stress induces the upregulation of HuAAE3, a gene involved in oxalate degradation, and its expression is regulated by the transcription factor HubHLH36. Molecular assays confirmed that HubHLH36 binds directly to the HuAAE3 promoter, enhancing its transcription.

Functional studies showed that overexpression of HuAAE3 or HubHLH36 reduces oxalate accumulation, improves salt and oxalate tolerance, and decreases reactive oxygen species (ROS) levels. In contrast, gene silencing had opposite effects. These findings were validated in Arabidopsis, supporting the conserved role of this regulatory module.

This work identifies the HubHLH36–HuAAE3 module as a key pathway for salt tolerance in pitaya and offers a genetic framework for breeding salt-tolerant cultivars.

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