Rapid and Accurate Detection of Marssonina coronaria in Apple Trees Using Loop-Mediated Isothermal Amplification

Marssonina blotch of apple is a well-known plant disease caused by Marssonina coronaria, which can cause severe economic consequences. Because of the importance of early diagnosis for effective plant disease management, we aimed to develop a loop-mediated isothermal amplification (LAMP) assay that could rapidly detect M. coronaria in apple plants. The ribosomal DNA internal transcribed spacer (rDNA-ITS) sequence of M. coronaria was selected as the target for primer design. Our results showed optimal conditions for the LAMP reaction at 62°C for 50 min, as indicated by color change and gel electrophoresis. The LAMP assay demonstrated specific discriminatory capability in differentiating M. coronaria from other pathogenic fungi in apple plants. In addition, the sensitivity tests revealed a detection limit of 100 fg/μl genomic DNA and 100 spores of M. coronaria for the LAMP assay. Finally, we successfully applied the LAMP assay to detect M. coronaria in apple leaf samples from the field. In general, our study provided a straightforward and efficient method for rapid diagnosis of apple blotch caused by M. coronaria, which could be applied in field conditions and used to detect early occurrence of the disease caused by M. coronaria.