TaHSP90 stabilizes Lr13 to regulate temperature-sensitive resistance to leaf rust in wheat seedlings

Area of Science:

• Plant Pathology
• Molecular Plant Breeding
• Climate Change Adaptation

Background:

• Global wheat production faces threats from increasing leaf rust pressure due to climate warming.
• Durable resistance strategies are essential to ensure food security.
• Understanding temperature-dependent resistance mechanisms is critical for breeding resilient wheat varieties.

Purpose of the Study:

• To investigate the molecular mechanisms underlying temperature-sensitive leaf rust resistance conferred by the Lr13 gene in wheat.
• To identify proteins interacting with Lr13 and regulating its function under different temperature conditions.
• To elucidate how Lr13 maintains resistance at elevated temperatures.

Main Methods:

• Transcriptomic analysis to assess gene expression changes under varying temperatures.
• Histochemical staining to quantify salicylic acid (SA) signaling and reactive oxygen species (ROS) accumulation.
• Affinity purification coupled with mass spectrometry (AP-MS) to identify Lr13-interacting proteins.
• Protein interaction assays and degradation assays to confirm protein interactions and stability.

Main Results:

• Lr13 induced higher SA signaling and ROS accumulation at 25°C compared to 18°C.
• TaHSP90 was identified as a key thermoregulatory protein interacting with Lr13 during Puccinia triticina infection.
• Lr13, in complex with HSP90-RAR1, bypassed 26S-proteasome degradation, maintaining SA gene expression and ROS burst at higher temperatures.
• TaHSP90 positively regulates the temperature-sensitive resistance conferred by Lr13.

Conclusions:

• TaHSP90 plays a crucial role in maintaining the efficacy of the Lr13 leaf rust resistance gene at elevated temperatures.
• The interaction between Lr13 and TaHSP90 provides a mechanism for temperature-sensitive resistance, involving SA signaling and ROS production.
• These findings offer strategic insights for developing climate-resilient wheat varieties with durable rust resistance.