Investigating Biochemical and Histopathological Responses between Raspberries and Aculeastrum americanum

Author(s)

Dias, Marcia Goncalves ; Sposito, Marcel Bellato ; Tessmer, Magda Andreia ; Appezzato da Gloria, Beatriz

• Document type: Journal article
• Source: JOURNAL OF FUNGI; v. 9, n. 3, p. 15-pg., 2023-03-01.

Abstract

Late leaf rust is a fungal disease in raspberries caused by Aculeastrum americanum (Farl.) M. Scholler U. Braun (syn. Thekopsora americana (Farl.) Aime McTaggart) leading to early defoliation and yield losses. Red raspberries (Rubus idaeus L.) are susceptible to this pathogen, although this susceptibility varies among cultivars. In contrast, black raspberries were previously reported to be more resistant (Rubus occidentalis L.) and immune (Rubus niveus Thunb.) to this pathogen, raising their importance in plant breeding programs. However, what features make them respond differently to the same pathogen? In this study, we characterize for the first time the pre- and post-formed structural and biochemical defense mechanisms of R. idaeus cv. Autumn Bliss, R. occidentalis and R. niveus. Ultrastructural and histopathological analyses were used to uncover the interactions between these raspberries and A. americanum. The ultrastructural results indicate that the pathogen germinates on both leaf surfaces but can only form appressoria on the stomata. Although the three raspberry species were infected and colonized by A. americanum, a clear difference in susceptibility was observed between them. A compact mesophyll, pre- and post-formed phenolic compounds, and post-formed pectic compounds were the main plant defense mechanisms against fungal colonization. These findings provide new information about raspberries' defense mechanisms in response to A. americanum and elucidate the interactions occurring in these pathosystems. (AU)

• FAPESP's process: 19/13191-5 - Epidemiological components, damage characterization and control of tropical and temperate rusts at a global climate change scenario
• Grantee: Marcel Bellato Spósito
• Support Opportunities: Research Projects - Thematic Grants
• FAPESP's process: 18/17428-7 - Anatomical and biochemical comparison among raspberry species (Rubus spp.) with different resistance levels to late leaf rust (Pucciniastrum americanum)
• Grantee: Márcia Gonçalves Dias
• Support Opportunities: Scholarships in Brazil - Doctorate