Passiflora mucronata, a passion fruit wild species resistant to fusariosis and a potential rootstock for commercial varieties

Passiflora mucronata Lam. offers a reservoir for the control of fusariosis in passion fruit. Fusariosis, a fungal disease caused by Fusarium oxysporum f. sp. passiflorae and species of the Fusarium solani complex, can dramatically reduce productivity and lead to premature death of infected plants. This study aimed to assess the resistance of ten P. mucronata genotypes (G1 to G10) to F. oxysporum f. sp. passiflorae and F. solani isolates. Plants grown for 45 days in autoclaved soil, were inoculated with i) two separate F. oxysporum f. sp. passiflorae isolates, ii) a mixture of three F. oxysporum f. sp. passiflorae isolates, iii) two separate F. solani isolates, and iv) a mixture of seven F. solani isolates. The roots were immersed in a spore suspension for 60 min and plantlets were grown for 90 days. Inoculated plants of G2 and G5 exhibited the same growth and accumulation of shoot and root dry matter as non-inoculated plants, 100% survival, and no internal or external tissue damage, suggesting immunity to fusariosis. Genotype G9 grew normally in a disease-prone environment, suggesting horizontal resistance. These genotypes can be used as rootstocks for breeding of commercial passion fruit varieties, as they can be classified resistant to F. oxysporum f. sp. passiflorae and F. solani isolates.