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Winters NP, Wafula EK, Knollenberg BJ, Hämälä T, Timilsena PR, Perryman M, Zhang D, Sheaffer LL, Praul CA, Ralph PE, Prewitt S, Leandro-Muñoz ME, Delgadillo-Duran DA, Altman NS, Tiffin P, Maximova SN, dePamphilis CW, Marden JH, Guiltinan MJ. A combination of conserved and diverged responses underlies Theobroma cacao's defense response to Phytophthora palmivora. BMC Biol 2024; 22:38. [PMID: 38360697 PMCID: PMC10870529 DOI: 10.1186/s12915-024-01831-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2023] [Accepted: 01/23/2024] [Indexed: 02/17/2024] Open
Abstract
BACKGROUND Plants have complex and dynamic immune systems that have evolved to resist pathogens. Humans have worked to enhance these defenses in crops through breeding. However, many crops harbor only a fraction of the genetic diversity present in wild relatives. Increased utilization of diverse germplasm to search for desirable traits, such as disease resistance, is therefore a valuable step towards breeding crops that are adapted to both current and emerging threats. Here, we examine diversity of defense responses across four populations of the long-generation tree crop Theobroma cacao L., as well as four non-cacao Theobroma species, with the goal of identifying genetic elements essential for protection against the oomycete pathogen Phytophthora palmivora. RESULTS We began by creating a new, highly contiguous genome assembly for the P. palmivora-resistant genotype SCA 6 (Additional file 1: Tables S1-S5), deposited in GenBank under accessions CP139290-CP139299. We then used this high-quality assembly to combine RNA and whole-genome sequencing data to discover several genes and pathways associated with resistance. Many of these are unique, i.e., differentially regulated in only one of the four populations (diverged 40 k-900 k generations). Among the pathways shared across all populations is phenylpropanoid biosynthesis, a metabolic pathway with well-documented roles in plant defense. One gene in this pathway, caffeoyl shikimate esterase (CSE), was upregulated across all four populations following pathogen treatment, indicating its broad importance for cacao's defense response. Further experimental evidence suggests this gene hydrolyzes caffeoyl shikimate to create caffeic acid, an antimicrobial compound and known inhibitor of Phytophthora spp. CONCLUSIONS Our results indicate most expression variation associated with resistance is unique to populations. Moreover, our findings demonstrate the value of using a broad sample of evolutionarily diverged populations for revealing the genetic bases of cacao resistance to P. palmivora. This approach has promise for further revealing and harnessing valuable genetic resources in this and other long-generation plants.
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Affiliation(s)
- Noah P Winters
- IGDP Ecology, The Pennsylvania State University, 422 Huck Life Sciences Building, University Park, PA, 16803, USA
- Huck Institutes of the Life Sciences, The Pennsylvania State University, University Park, PA, USA
| | - Eric K Wafula
- Department of Biology, The Pennsylvania State University, University Park, PA, USA
| | | | - Tuomas Hämälä
- Department of Plant and Microbial Biology, University of Minnesota, St. Paul, MN, USA
- Department of Ecology and Genetics, University of Oulu, Oulu, Finland
| | - Prakash R Timilsena
- Department of Biology, The Pennsylvania State University, University Park, PA, USA
| | - Melanie Perryman
- Department of Plant Science, The Pennsylvania State University, University Park, PA, USA
| | - Dapeng Zhang
- Sustainable Perennial Crops Laboratory, U.S. Department of Agriculture-Agricultural Research Service, Beltsville, MD, USA
| | - Lena L Sheaffer
- Department of Plant Science, The Pennsylvania State University, University Park, PA, USA
| | - Craig A Praul
- Huck Institutes of the Life Sciences, The Pennsylvania State University, University Park, PA, USA
| | - Paula E Ralph
- Department of Biology, The Pennsylvania State University, University Park, PA, USA
| | - Sarah Prewitt
- Department of Plant Science, The Pennsylvania State University, University Park, PA, USA
| | | | | | - Naomi S Altman
- Department of Statistics, The Pennsylvania State University, University Park, PA, USA
| | - Peter Tiffin
- Department of Plant and Microbial Biology, University of Minnesota, St. Paul, MN, USA
| | - Siela N Maximova
- Huck Institutes of the Life Sciences, The Pennsylvania State University, University Park, PA, USA
- Department of Plant Science, The Pennsylvania State University, University Park, PA, USA
| | - Claude W dePamphilis
- Huck Institutes of the Life Sciences, The Pennsylvania State University, University Park, PA, USA
- Department of Biology, The Pennsylvania State University, University Park, PA, USA
- IGDP Plant Biology, The Pennsylvania State University, University Park, PA, USA
| | - James H Marden
- Huck Institutes of the Life Sciences, The Pennsylvania State University, University Park, PA, USA
- Department of Biology, The Pennsylvania State University, University Park, PA, USA
| | - Mark J Guiltinan
- Huck Institutes of the Life Sciences, The Pennsylvania State University, University Park, PA, USA.
- Department of Biology, The Pennsylvania State University, University Park, PA, USA.
- IGDP Plant Biology, The Pennsylvania State University, University Park, PA, USA.
- Department of Plant Science, The Pennsylvania State University, University Park, PA, USA.
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