C t TLP 13 Located in Extracellular Vesicles Enhances the Resistance of Safflower ( Carthamus tinctorius ) to Botrytis cinerea

Safflower (Carthamus tinctorius), a versatile economic crop of the Asteraceae family used for both medicinal and oil purposes, is widely cultivated worldwide. During its growth period, particularly during the harvesting phase, safflower is susceptible to fungal infections, leading to reduced product quality and yield. Currently, there is a lack of research on candidate genes associated with safflower disease resistance, which hinders the breeding of disease-resistant varieties of safflower. The disease severity index of 499 safflower germplasm lines during the flowering period was analysed through genome-wide association studies (GWAS), and a highly correlated TLP (thaumatin-like proteins) family disease resistance candidate gene, CtTLP13, was identified. Subsequently, transcriptomic and proteomic analyses were conducted to characterise the molecular features of safflower under fungal infection, and it was confirmed that CtTLP13 can respond to the biotic stress when safflower is infected by Botrytis cinerea. CtTLP13 overexpression in Arabidopsis and safflower enhanced safflower disease resistance; in vitro experiments confirmed its inhibition of B. cinerea growth and spore germination. We isolated safflower extracellular vesicles (EVs), verified CtTLP13 localisation within them and showed that CtTLP13-carrying safflower EVs are taken up by B. cinerea and inhibit the fungal growth. Overall, this study identified a valuable disease resistance gene (CtTLP13) in safflower. We also investigated the role of safflower EVs in disease resistance, and the results showed that safflower EVs exhibit anti-B. cinerea activity.