Proteomic Analysis of Banana Vascular Sap Provides Insight Into Resistance Mechanisms to Fusarium Oxysporum F. Sp. Cubense Tropical Race 4

Abstract Background: Fusarium oxysporum f. sp. cubense tropical race 4 (Foc TR4) is the causal agent of Fusarium wilt, and is the most destructive soil-borne and vascular invasive fungus of banana. The sap circulating in vascular cells transports proteins including those that might be involved in disease-resistance processes. However, there is no research to analyze changes in banana vascular sap protein response to TR4 to date. Results: To gain an integrated understanding of differential protein abundance in banana vascular sap during TR4 infection, we performed a comparative proteomic analysis of vascular sap of the resistant ‘Pahang’ and the susceptible ‘Brazilian’ bananas inoculated with TR4. We identified 129 differential expression proteins (DEPs) between resistant and susceptible tested combinations. Of these DEPs, hypersensitive-induced response protein 1 (HIR1) and E3 ubiquitin ligase (E3) decreased in abundance in Pahang with no change in Brazilian under TR4 infection; chalcone isomerase (CHI) and glycine-rich RNA-binding protein (GRP) increased in abundance in Pahang but no significant changes in Brazilian under TR4 infection; carboxylesterase (CXE) and GDSL lipase (GLIP) were specifically in higher abundance in Pahang response to TR4 compared to that of Brazilian. It suggested that these proteins played important roles in bananas against TR4. Conclusions: Our study identified 129 DEPs in vascular sap between resistant and susceptible tested combinations. Of which, HIR1, E3, CHI, GRP, CXE and GLIP played important roles in bananas response to TR4. To our knowledge, this is first report to analyze changes in banana vascular sap proteins in response to TR4, which help us to explore the molecular mechanisms of banana defense to Fusarium wilt.