Diseases

Alternaria Blotch of Apple

Malus domestica (Suckow) Borkh.

A fungal disease caused by a specific pathotype of Alternaria alternata via the production of AM-toxin, characterized by necrotic leaf spotting, fruit decay, and premature defoliation.

In the reference 6 varieties crop Apple, where this is mentioned in the description.

The disease is caused by the apple pathotype of the fungus Alternaria alternata. Its pathogenicity is determined by the presence of genes for the synthesis of specific AM-toxin, located on conditionally dispensable chromosomes. Symptoms on leaves manifest as small dark-brown spots with purple margins, which lead to leaf drop as they expand, while symptoms on fruits appear as depressed lesions and internal core rot.

Genetic control of disease resistance is linked to the functioning of the dominant Alt gene: the susceptibility allele determines the infection of 'Delicious' group cultivars, whereas the alt/alt genotype provides resistance. In addition to the classic Alt gene, apple defense responses involve NBS-LRR proteins and specific transcription factors, such as MdMYB6-like, which regulate the plant's immune response to the pathogen.

General information about the subject — on the page Alternaria blight.

Sources8

Varieties of Apple mentioned in the description

Selection based on the description text, not on official evaluation: these data are absent from registers. For specific variety details, please refer to its profile.