An Overview of the Mechanisms Involved in Coffee-Hemileia vastatrix Interactions: Plant and Pathogen Perspectives

Abstract

Coffee is one of the most consumed beverages in the world. It is also one of the most globally traded commodities. Coffee leaf rust (CLR), caused by the biotrophic fungus Hemileia vastatrix, is the most important disease affecting Arabica coffee growing worldwide, leading to significant yield losses if no control measures are applied. A deep understanding of the complex mechanisms involved in coffee-H. vastatrix interactions, such as the pathogen variability and the mechanisms governing plant resistance and susceptibility, is required to breed efficiently for durable resistance and design new approaches for crop protection. Here we summarize our current understanding across multiple areas related to pathogen infection, variability and candidate effectors, breeding for disease resistance, and the various components of the coffee immune system, by reviewing a comprehensive body of research on CLR and the advances recently made. We also update information about the defense responses activated by the application of plant resistance inducers, a promising alternative to fungicides in the control of CLR. Moreover, we identify and discuss future directions for further research.

A chromosome-level genome resource for studying virulence mechanisms and evolution of the coffee rust pathogen Hemileia vastatrix

“…Latest reports estimate production losses in excess of $1 billion annually worldwide (Kahn 2019). Furthermore, during the last decade, a cluster of epidemic outbreaks known as "the big rust" burst out across Latin America and the Caribbean on a level similar to the one observed in Ceylon; this extended both the temporal and spatial range of the disease, conferring to CLR the status of "natural disaster" in the tropics (Avelino et al 2015;McCook and Vandermeer 2015;Silva et al 2022).…”

“…The rapid evolution of H. vastatrix to overcome resistance in coffee cultivars is even more puzzling considering that the pathogen exists almost exclusively in the asexual urediniospore stage of its life cycle and that the dikaryotic urediniospores are the only known functional propagules (Talhinhas et al 2017b;Silva et al 2018Silva et al , 2022Koutouleas et al 2019a). Hemileia vastatrix is a hemicyclic fungus producing urediniospores, teliospores and basidiospores, but teliospores occur very rarely (Chinnappa and Sreenivasan 1965;Coutinho et al 1995;Fernandes et al 2009) and basidiospores do not re-infect coffee (Rodrigues et al 1980;Kushalappa and Eskes 1989).…”

“…2022). As a result of the high ability of the pathogen to respond rapidly to selection pressure, more than 55 physiological races have been identified to date (Silva et al . 2022).…”

“…However, no direct link between such high phenotypic diversity and molecular diversity has yet been found, and no virulence locus has characterized so far (Talhinhas et al . 2017b; Silva et al . 2022).…”

Composition and Diversity of LTR Retrotransposons in the Coffee Leaf Rust Genome (Hemileia vastatrix)

“…It was responsible for the collapse of coffee production in India and Ceylon by the mid-19th century [6]. Over 55 Hva races have been reported throughout the world [4,7], and they have been shown to have a great genetic diversity using RAPD and AFLP [8,9] and sequences of internal transcribed sequences (ITS) [10].…”