Putative priming effect of Seguieria langsdorffii Moq. leaf extract in Cucurbita pepo L. infected by zucchini yellow mosaic virus

Cucurbita pepo L., an important crop in Brazil, can be infected by zucchini yellow mosaic virus (ZYMV), an aphid-transmitted Potyvirus. To avoid the use of insecticides, sustainable control could involve the application of leaf extracts (LE) with antiviral activity, particularly Caryophyllales species. However, the mode of action is unclear. This study aimed to evaluate the defense responses of C. pepo 'Caserta' infected with ZYMV (VI) compared to plants treated with LE from the Brazilian native species Seguieria langsdorffii, order Caryophyllales, and those treated with LE before ZYMV inoculation (LEVI). Cotyledonary leaves were collected on the same day, one, five, and ten days after inoculation (D0, D1, D5, and D10). Polyamines were identified using a calibration curve of putrescine, spermidine (Spd), and spermine (Spm) samples. Ascorbate and glutathione were identified and quantified using a calibration curve of ascorbic acid and glutathione samples. Metabolomic analysis was also performed based on the metabolic profile, using gas chromatography coupled with mass spectrometry, and quantified using ribitol as the internal standard. There was an increase in Spd and Spm and ascorbate contents in plants from the LEVI treatment on D0 and D10, respectively. Shikimate levels were higher in the LE group on D0 and D1. We suggest that LE may have exerted a priming effect, which could have helped the plant respond to the viral infection, based primarily on spermine and shikimate contents.