Characterization of fungi resistance in two autotetraploid apple cultivars

- Disease resistance traits of diploid and autotetraploid apple plants ('Hanfu' and 'Gala') are reported.
- The differences indicate that apple plants ('Hanfu' and 'Gala') may differ in their response to biotic stress depending on ploidy level.
- Disease resistance-related genes (like CERK1, PR1, WRKY29) were response to the A. alternata and C. gloeosporiodes infection in apple.

Polyploidy is a key innovation in plant evolution that allows plants to adapt to various biotic stresses. Autotetraploid apple trees (Malus × domestica) perform better in the field than do diploid apple trees. Fungal diseases seriously affect the apple industry, and due to the long growth period of autopolyploid woody plants, little information is available on breeding disease-resistant artificially induced autotetraploid. The study aimed to evaluate the difference in disease resistance between autotetraploid and diploid apple plants and the difference in the expression levels of related genes that may be involved in disease resistance.Two autotetraploid apple cultivars, 'Hanfu' and 'Gala', perform better in response to Alternaria alternata and Colletotrichum gloeosporioides in that disease spot is smaller, infection is lighter and disease incidence is lower than those in the diploid. Real-time quantitative PCR analysis revealed that disease resistance-related genes were remarkably up-regulated in autotetraploid plants. These results could provide a theoretical basis for breeding disease-resistant autopolyploid apple plants.