Genome-wide identification of the peanut PITP gene family and functional verification of AhSFH8 in resistance to Aspergillus flavus infection.

Phosphatidylinositol transfer proteins (PITPs) are essential in eukaryotes for transporting phosphatidylinositol and phosphatidylcholine monomers across intracellular membranes, and they play key roles in regulating plant growth, signal transduction, stress responses, and other vital biological processes. Arachis hypogaea L., the crop most susceptible to Aspergillus flavus, has not been reported its PITP genes in responses to A. flavus infection. In this study, we performed a genome-wide identification of the PITP gene family in the peanut cultivar Tifrunner using the latest reference genome, and analyzed their expression patterns in different peanut tissues and at various time points after A. flavus inoculation. Furthermore, we cloned a candidate gene, AhSFH8 (a member of the PITP family's SFH subfamily, which contains Sec14-Nodulin or NIJ16 domains) from the highly A. flavus-resistant peanut material "J11" and validated its function via overexpression in tobacco. A total of 85 peanut PITP genes (AhPITPs) were identified, which were classified into three subfamilies and distributed across 20 chromosomes. Segmental duplication was found to be the main driver for the expansion of this family, and gene structure, motif, and conserved domain analyses confirmed their structural conservation. Promoter cis-acting element analysis showed that SFH subfamily members harbored more stress-related elements, suggesting their involvement in stress responses. Expression profiling revealed that three SFH genes (AhSFH8, AhSFH9, AhSFH10) were potentially associated with A. flavus resistance. Cloning of AhSFH8 from "J11" showed its target fragment is 1917 bp in length, with premature translation termination at 1836 bp. Transgenic tobacco overexpressing AhSFH8 exhibited significantly less leaf yellowing and fewer surface spores than wild-type tobacco after A. flavus infection, preliminarily confirming that AhSFH8 enhances A. flavus resistance. Based on gene family identification, promoter analysis, expression patterns and transgenic functional validation, we identified three SFH genes potentially associated with resistance to A. flavus infection. Our findings provide a foundation for understanding the functions of the peanut PITP gene family and the mechanism underlying AhSFH8-mediated resistance to A. flavus infection, while also offering valuable candidate genes for peanut resistance breeding.