First Report of Leaf Spot Disease Caused by Alternaria jacinthicola on Tagetes erecta in China

A New Leaf Blight Disease Caused by Alternaria jacinthicola on Banana in China

A leaf blight disease with an incidence level of about 50% was found on Robusta banana in Guangdong province of China in September 2020. The early symptom appeared as pale gray to black brown, irregular, small, necrotic lesions mainly on the top 3–5 leaves. Severely infected leaves were withered and necrotic. Two representative fungus strains, strain L1 and strain L2, were isolated from affected banana leaves, and morphological and molecular identification analysis confirmed that the two fungi were both Alternaria jacinthicola. Many Alternaria species have been reported to cause wilting, decay, leaf blight and leaf spots on plants and lead to serious economic losses in their production, including A. alternata, causing leaf blight and leaf sport diseases on banana. The Koch’s postulates of A. jacinthicola causing the leaf blight disease was further fulfilled, which confirmed that it is the causal agent of this disease. To our knowledge, this is the first report of A. jacinthicola causing leaf blight on banana in China.

Alternaria koreana sp. nov., a new pathogen isolated from leaf spot of ovate-leaf Atractylodes in South Korea

BACKGROUND

A new species within the genus Alternaria was isolated from the leaf spot of Atractylodes ovata in the Mungyeong and Hwabuk-myeon districts of the Gyeongbuk province of Korea. The leaves showed disease symptoms such as circular or irregular leaf spots and brown to dark brown with gray spots at the center. The leaves also showed that concentric rings were surrounded with yellow halos.

METHODS AND RESULTS

Phylogenetic analysis was conducted using the sequence dataset of the internal transcribed spacer region and part of the glyceraldehyde-3-phosphate dehydrogenase. The RNA polymerase II second largest subunit, endopolygalacturonase, Alternaria major allergen gene, anonymous gene region, and translation elongation factor 1-alpha genes were used as well. Results showed that present fungal isolates were distinct from other species of the sect. Alternaria. Morphologically, the present isolates also differed from other members of the sect. Alternaria in their production of solitary conidia or conidial chains (two units) and conidial body features. Similarly, it exhibited moderate pathogenicity in the host plant.

CONCLUSIONS

This study described and illustrated A. koreana as a new species and the causal agent of the leaf-spot disease on A. ovata in Korea.