Genome-wide analysis of the wheat LIFEGUARD gene family and functional characterization of TaLFG32 in response to stripe rust

Abstract Background Wheat stripe rust, caused by the obligate biotrophic fungus Puccinia striiformis f. sp. tritici ( Pst ), poses a major threat to global wheat production. Although breeding resistant cultivars remains the most effective strategy for controlling stripe rust, resistance conferred by race-specific genes is often overcome by rapidly evolving Pst populations. Targeting host factors required for pathogen colonization therefore represents a complementary strategy for developing broad-spectrum and durable resistance. LIFEGUARD (LFG) proteins regulate cell death and have been implicated in plant susceptibility to biotrophic powdery mildew fungi, but their functions in wheat and the wheat- Pst interaction remain largely unknown. Results A total of 32 TaLFG genes were identified in wheat, unevenly distributed across 13 chromosomes, and classified into three subfamilies. Collinearity analysis revealed that segmental duplication was the predominant duplication mechanism contributing to the expansion of the wheat LFG gene family. Promoter analysis revealed abundant cis-acting elements associated with light, hormones, and stress responses. Expression profiling showed that several TaLFG genes were constitutively expressed in different wheat tissues. Among the seven genes examined following Pst inoculation, TaLFG32 was strongly induced during the compatible interaction with CYR31 but was repressed at 48 h post-inoculation during the incompatible interaction with CYR23. TaLFG32 was localized to the plasma membrane. Virus-induced gene silencing and overexpression analyses suggested that TaLFG32 negatively regulates wheat resistance to stripe rust, by limiting reactive oxygen species (ROS) accumulation and host cell death. Conclusions These findings provide a systematic basis for understanding the wheat LFG gene family and establish TaLFG32 as a negative regulator of stripe rust resistance, offering a potential target for wheat resistance improvement.