Genome-wide identification of GAPDH gene family and functional analysis of CaGAPC2-mediated autophagy during BWYV infection in pepper

BACKGROUND: Glyceraldehyde-3-phosphate dehydrogenases (GAPDHs) are glycolytic enzymes involved in plant metabolism, growth, signal transduction and stress responses. Beet western yellows virus (BWYV), which belongs to the Polerovirus, causes substantial yield and quality losses in pepper. However, the roles of GAPDHs in pepper responses to BWYV infection remain largely unexplored. RESULTS: Transcriptome analyses revealed altered expression of GAPDH genes in Capsicum annuum following BWYV infection. Genome-wide analysis identified seven CaGAPDH genes in pepper, and qRT-PCR showed that CaGAPC2 transcripts were most strongly down-regulated after infection. Previous studies have shown that GAPCs contribute to autophagy regulation. Here, silencing CaGAPC2 enhances autophagy and reduces BWYV accumulation, and BWYV CP-RT was targeted for autophagic degradation through its interaction with the key autophagy protein ATG8f. Furthermore, autophagy activator BTH treatment inhibits BWYV infection. CONCLUSION: This study establishes that CaGAPC2 functions as a negative regulator of autophagy; its silencing enhances autophagy and limits BWYV. CP-RT interacts with ATG8f and is degraded by the autophagy pathway. Critically, activating autophagy using BTH effectively inhibits BWYV infection. These findings elucidate a CaGAPC2-mediated molecular defense mechanism against BWYV and provide a foundation for developing novel control strategies.