Abstract
The biotrophic fungus Hemileia vastatrix causes coffee leaf rust (CLR), one of the most devastating diseases in Coffea arabica . Coffee, like other plants, has developed effective mechanisms to recognize and respond to infections caused by pathogens. Plant resistance gene analogs (RGAs) have been identified in certain plants as candidates for resistance ( R ) genes or membrane receptors that activate the R genes. The RGAs identified in different plants possess conserved domains that play specific roles in the fight against pathogens. Despite the importance of RGAs, in coffee plants these genes and other molecular mechanisms of disease resistance are still unknown. This study aimed to sequence and characterize candidate genes from coffee plants with the potential for involvement in resistance to H. vastatrix . Sequencing was performed based on a library of bacterial artificial chromosomes (BAC) of the coffee clone ‘Híbrido de Timor’ (HdT) CIFC 832/2 and screened using a functional marker. Two RGAs, HdT_LRR_RLK1 and HdT_LRR_RLK2, containing the motif of leucine-rich repeat-like kinase (LRR-RLK) were identified. Based on the presence or absence of the HdT_LRR_RLK2 RGA in a number of differential coffee clones containing different combinations of the rust resistance gene, these RGAs did not correspond to any resistance gene already characterized (SH1-9). These genes were also analyzed using qPCR and demonstrated a major expression peak at 24 h after inoculation in both the compatible and incompatible interactions between coffee and H. vastatrix . These results are valuable information for breeding programs aimed at developing CLR-resistant cultivars, in addition to enabling a better understanding of the interactions between coffee and H. vastatrix .
Highlights
For many centuries, rust diseases have been a major threat to many crops, causing severe damage to farming activities
Based on the presence or absence of the HdT_LRR_RLK2 resistance gene analogs (RGAs) in a number of differential coffee clones containing different combinations of the rust resistance gene, these RGAs did not correspond to any resistance gene already characterized (SH1-9)
Pattern-triggered immunity (PTI) is triggered by pathogen-associated molecular patterns (PAMP) and the second line of defense, effector-triggered immunity (ETI) fit the gene-for-gene theory proposed by Flor (1971), and (Dodds and Rathjen, 2010)
Summary
Rust diseases have been a major threat to many crops, causing severe damage to farming activities. In coffee (Coffea arabica), leaf rust, caused by the biotrophic fungus Hemileia vastatrix, is the most devastating disease worldwide (Zambolim, 2016). Pattern-triggered immunity (PTI) is triggered by pathogen-associated molecular patterns (PAMP) and the second line of defense, effector-triggered immunity (ETI) fit the gene-for-gene theory proposed by Flor (1971), and (Dodds and Rathjen, 2010). This theory explains the interaction between coffee and H. vastatrix, whereby the resistance of coffee plants is conditioned by at least nine dominant genes with main effects (SH1SH9). The SH1, SH2, SH4, and SH5 genes are found in C. arabica, whereas SH6, SH7, SH8, and SH9 are present in C. canephora and SH3 is found in C. liberica (Noronha-Wagner and Bettencourt, 1967; Bettencourt and Noronha-Wagner, 1971; Bettencourt et al, 1980; Bettencourt and Rodrigues, 1988)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
