U.S. flagAn official website of the United States government
                    Here's how you know **Official websites use .gov**
                            
                            A **.gov** website belongs to an official government organization in the United States.
 **Secure .gov websites use HTTPS**
                            
                            A **lock** (                            
                              A locked padlock                                                      
                            
                            ) or **https://** means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.


Menu Agricultural Research Service
						
                    U.S. DEPARTMENT OF AGRICULTURE
 Sustainable Perennial Crops Laboratory: Beltsville, MD
 close



    Research

                    Research Projects
                                    Publications
                                    Collaborations
                                    News
                People

                    Staff Listing
                                    CareersSearch small
                    Search
            
            ARS Home
                                About ARS
                                Contact Us




ARS Home Northeast Area Beltsville, Maryland (BARC) Beltsville Agricultural Research Center Sustainable Perennial Crops Laboratory Research Publications at this Location





- ARS National Programs
- Search for a scientific manuscript
- Search for a research project
- ARS Software
- Programs and Projects
- Collaborations
- Subjects of Investigation
- Publications

Title:   Author  item
                                            Bailey, Bryanitem
                                            MELNICK, RACHEL - National Institute Of Food And Agriculture (NIFA)item
                                            Strem, Maryitem
                                            CROZIER, JANE - Catie Tropical Agricultural Researchitem
                                            Shao, Jonathanitem
                                            Sicher  Jr, Richarditem
                                            ALI, SHAHIN - Forest Service (FS)item
                                            Zhang, Dapengitem
                                            PHILIPS-MORA, WILBERTH - Catie Tropical Agricultural Researchitem
                                            Meinhardt, Lyndel
  Submitted to: Molecular Plant Pathology
                                    Publication Type: Peer Reviewed Journal
                                    Publication Acceptance Date: 2/25/2014
                                    Publication  Date: 2/25/2014
                                    Citation: Bailey, B.A., Melnick, R.L., Strem, M.D., Crozier, J., Shao, J.Y., Sicher, Jr., R.C., Ali, S.S., Zhang, D., Philips-Mora, W., Meinhardt, L.W. 2014. Differential gene expression by Moniliophthora roreri while overcoming cacao tolerance in the field. Molecular Plant Pathology. DOI:10.1111/mpp.12134.Interpretive Summary: The fungus Monilophthora roreri causes frosty pod rot, a devastating disease on Theobroma cacao (cacao), the source of chocolate. Cacao clones showing tolerance against frosty pod rot are being planted throughout Central America. A significant concern associated with the planting of tolerant clones is that the fungus may mutate and overcome the tolerance making them highly susceptible to frosty pod rot. We characterized fungal gene expression associated with infections of tolerant clones. The fungus alters its gene expression patterns when infecting tolerant clones, increasing expression of stress response genes. The genes identified likely contribute to the fungus overcoming cacao defense mechanisms in tolerant clones. By understanding how the fungus causes disease on tolerant cacao clones, we can optimize breeding programs that are selecting tolerance to frosty pod rot, influence farming practices associated with the use of tolerant clones, and extend the usefulness of tolerant clones in the field. Chocolate is combined with United States agricultural products providing direct benefit to the American farmer. The extended use of tolerant clones should help stabilize and increase cacao supplies resulting to increased benefits to the cacao farmer, the cacao industry, and the American farmer.
                                Technical Abstract: Frosty pod rot (FPR), caused by the hemibiotrophic fungus Moniliophthora roreri (Mr), can destroy 100% of pods in susceptible Theoborma cacao (cacao) fields under favorable conditions.  Cacao clones with high levels of tolerance to FPR are being deployed throughout Central America. To determine whether Mr had a differential molecular response during successful infections of tolerant clones, we collected field infected pods at all stages of symptomology for five cacao clones. Two clones were highly susceptible (Pound-7 and CATIE-1000) and three clones were tolerant (UF-273, CATIE-R7, and CATIE-R4). RNA-Seq analysis of RNA samples from infected pods of Pound-7, CATIE-1000, CATIE-R4 and CATIE-R7 identified a set of 872 Mr genes that were differentially expressed between clones with the primary difference being whether the clone was susceptible or tolerant to FPR. Metabolite analysis was also carried out. As FPR progressed, the concentrations of sugars in pods of Pound-7, CATIE-1000, CATIE-R7, and CATIE-R4 dropped while levels of trehalose and mannitol increased. Associations between disease parameters (symptoms and infection level) and some organic and amino acids concentrations varied depending on the clone considered. The differential Mr gene expression between clones of a subset of forty two Mr genes was validated by RT-qPCR. Expression of Mr genes in the majority of infected pods from tolerant clones resembled that observed in the necrotrophic phase of the disease cycle. Mr transcription factors, small heat proteins, transporters, enzymes modifying fungal or plant membranes or cell walls, and several metabolic processes including the glyoxylate cycle and alternative oxidase were differentially expressed between tolerant and susceptible clones.  Successful Mr infection of tolerant clones, although uncommon, altered expression of Mr genes which may benefit the fungus in overcoming cacao defense mechanisms.


Return to top


Connect with ARS Sign up


ARS Home
                            USDA.gov
                            Plain Writing
                            Policies & Links
                            Civil Rights Statements
                            FOIA
                            Accessibility Statement
                            Privacy Policy
                            Non-Discrimination Statement
                            Quality of Information
                            USA.gov
                            WhiteHouse.gov