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Ding Y, Weckwerth PR, Poretsky E, Murphy KM, Sims J, Saldivar E, Christensen SA, Char SN, Yang B, Tong AD, Shen Z, Kremling KA, Buckler ES, Kono T, Nelson DR, Bohlmann J, Bakker MG, Vaughan MM, Khalil AS, Betsiashvili M, Dressano K, Köllner TG, Briggs SP, Zerbe P, Schmelz EA, Huffaker A. Genetic elucidation of interconnected antibiotic pathways mediating maize innate immunity. Nat Plants 2020; 6:1375-1388. [PMID: 33106639 DOI: 10.1038/s41477-020-00787-9] [Citation(s) in RCA: 39] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/16/2020] [Accepted: 09/11/2020] [Indexed: 05/24/2023]
Abstract
Specialized metabolites constitute key layers of immunity that underlie disease resistance in crops; however, challenges in resolving pathways limit our understanding of the functions and applications of these metabolites. In maize (Zea mays), the inducible accumulation of acidic terpenoids is increasingly considered to be a defence mechanism that contributes to disease resistance. Here, to understand maize antibiotic biosynthesis, we integrated association mapping, pan-genome multi-omic correlations, enzyme structure-function studies and targeted mutagenesis. We define ten genes in three zealexin (Zx) gene clusters that encode four sesquiterpene synthases and six cytochrome P450 proteins that collectively drive the production of diverse antibiotic cocktails. Quadruple mutants in which the ability to produce zealexins (ZXs) is blocked exhibit a broad-spectrum loss of disease resistance. Genetic redundancies ensuring pathway resiliency to single null mutations are combined with enzyme substrate promiscuity, creating a biosynthetic hourglass pathway that uses diverse substrates and in vivo combinatorial chemistry to yield complex antibiotic blends. The elucidated genetic basis of biochemical phenotypes that underlie disease resistance demonstrates a predominant maize defence pathway and informs innovative strategies for transferring chemical immunity between crops.
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Affiliation(s)
- Yezhang Ding
- Section of Cell and Developmental Biology, University of California at San Diego, La Jolla, CA, USA
| | - Philipp R Weckwerth
- Section of Cell and Developmental Biology, University of California at San Diego, La Jolla, CA, USA
| | - Elly Poretsky
- Section of Cell and Developmental Biology, University of California at San Diego, La Jolla, CA, USA
| | - Katherine M Murphy
- Department of Plant Biology, University of California Davis, Davis, CA, USA
| | - James Sims
- ETH Zurich, Institute of Agricultural Sciences, Zurich, Switzerland
| | - Evan Saldivar
- Section of Cell and Developmental Biology, University of California at San Diego, La Jolla, CA, USA
| | - Shawn A Christensen
- Chemistry Research Unit, Center for Medical, Agricultural and Veterinary Entomology, Department of Agriculture, Agricultural Research Service, Gainesville, FL, USA
| | - Si Nian Char
- Division of Plant Sciences, Bond Life Sciences Center, University of Missouri, Columbia, MO, USA
| | - Bing Yang
- Division of Plant Sciences, Bond Life Sciences Center, University of Missouri, Columbia, MO, USA
- Donald Danforth Plant Science Center, St Louis, MO, USA
| | - Anh-Dao Tong
- Section of Cell and Developmental Biology, University of California at San Diego, La Jolla, CA, USA
| | - Zhouxin Shen
- Section of Cell and Developmental Biology, University of California at San Diego, La Jolla, CA, USA
| | - Karl A Kremling
- Department of Plant Breeding and Genetics, Cornell University, Ithaca, NY, USA
| | - Edward S Buckler
- Department of Plant Breeding and Genetics, Cornell University, Ithaca, NY, USA
- Robert W. Holley Center for Agriculture and Health, Ithaca, US Department of Agriculture, Agricultural Research Service, New York, NY, USA
| | - Tom Kono
- Minnesota Supercomputing Institute, University of Minnesota, Minneapolis, MN, USA
| | - David R Nelson
- University of Tennessee Health Science Center, Memphis, TN, USA
| | - Jörg Bohlmann
- Michael Smith Laboratories, University of British Columbia, Vancouver, British Columbia, Canada
| | - Matthew G Bakker
- National Center for Agricultural Utilization Research, US Department of Agriculture, Agricultural Research Service, Peoria, IL, USA
- Department of Microbiology, University of Manitoba, Winnipeg, Manitoba, Canada
| | - Martha M Vaughan
- National Center for Agricultural Utilization Research, US Department of Agriculture, Agricultural Research Service, Peoria, IL, USA
| | - Ahmed S Khalil
- Section of Cell and Developmental Biology, University of California at San Diego, La Jolla, CA, USA
| | - Mariam Betsiashvili
- Section of Cell and Developmental Biology, University of California at San Diego, La Jolla, CA, USA
| | - Keini Dressano
- Section of Cell and Developmental Biology, University of California at San Diego, La Jolla, CA, USA
| | | | - Steven P Briggs
- Section of Cell and Developmental Biology, University of California at San Diego, La Jolla, CA, USA
| | - Philipp Zerbe
- Department of Plant Biology, University of California Davis, Davis, CA, USA
| | - Eric A Schmelz
- Section of Cell and Developmental Biology, University of California at San Diego, La Jolla, CA, USA
| | - Alisa Huffaker
- Section of Cell and Developmental Biology, University of California at San Diego, La Jolla, CA, USA.
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Mafu S, Ding Y, Murphy KM, Yaacoobi O, Addison JB, Wang Q, Shen Z, Briggs SP, Bohlmann J, Castro-Falcon G, Hughes CC, Betsiashvili M, Huffaker A, Schmelz EA, Zerbe P. Discovery, Biosynthesis and Stress-Related Accumulation of Dolabradiene-Derived Defenses in Maize. Plant Physiol 2018; 176:2677-2690. [PMID: 29475898 PMCID: PMC5884620 DOI: 10.1104/pp.17.01351] [Citation(s) in RCA: 68] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/19/2017] [Accepted: 02/16/2018] [Indexed: 05/18/2023]
Abstract
Terpenoids are a major component of maize (Zea mays) chemical defenses that mediate responses to herbivores, pathogens, and other environmental challenges. Here, we describe the biosynthesis and elicited production of a class of maize diterpenoids, named dolabralexins. Dolabralexin biosynthesis involves the sequential activity of two diterpene synthases, ENT-COPALYL DIPHOSPHATE SYNTHASE (ZmAN2) and KAURENE SYNTHASE-LIKE4 (ZmKSL4). Together, ZmAN2 and ZmKSL4 form the diterpene hydrocarbon dolabradiene. In addition, we biochemically characterized a cytochrome P450 monooxygenase, ZmCYP71Z16, which catalyzes the oxygenation of dolabradiene to yield the epoxides 15,16-epoxydolabrene (epoxydolabrene) and 3β-hydroxy-15,16-epoxydolabrene (epoxydolabranol). The absence of dolabradiene and epoxydolabranol in Zman2 mutants under elicited conditions confirmed the in vivo biosynthetic requirement of ZmAN2. Combined mass spectrometry and NMR experiments demonstrated that much of the epoxydolabranol is further converted into 3β,15,16-trihydroxydolabrene (trihydroxydolabrene). Metabolite profiling of field-grown maize root tissues indicated that dolabralexin biosynthesis is widespread across common maize cultivars, with trihydroxydolabrene as the predominant diterpenoid. Oxidative stress induced dolabralexin accumulation and transcript expression of ZmAN2 and ZmKSL4 in root tissues, and metabolite and transcript accumulation were up-regulated in response to elicitation with the fungal pathogens Fusarium verticillioides and Fusarium graminearum Consistently, epoxydolabranol significantly inhibited the growth of both pathogens in vitro at 10 µg mL-1, while trihydroxydolabrene-mediated inhibition was specific to Fverticillioides These findings suggest that dolabralexins have defense-related roles in maize stress interactions and expand the known chemical space of diterpenoid defenses as genetic targets for understanding and ultimately improving maize resilience.
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Affiliation(s)
- Sibongile Mafu
- Department of Plant Biology, University of California, Davis, California
| | - Yezhang Ding
- Section of Cell and Developmental Biology, University of California, La Jolla, California
| | - Katherine M Murphy
- Department of Plant Biology, University of California, Davis, California
| | - Omar Yaacoobi
- Department of Plant Biology, University of California, Davis, California
| | - J Bennett Addison
- Department of Chemistry, San Diego State University, San Diego, California
| | - Qiang Wang
- College of Agronomy and Institute of Ecological Agriculture, Sichuan Agricultural University, Chengdu 611130, China
| | - Zhouxin Shen
- Section of Cell and Developmental Biology, University of California, La Jolla, California
| | - Steven P Briggs
- Section of Cell and Developmental Biology, University of California, La Jolla, California
| | - Jörg Bohlmann
- Michael Smith Laboratories, University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z4
| | - Gabriel Castro-Falcon
- Center for Marine Biotechnology and Biomedicine, Scripps Institution of Oceanography, University of California, La Jolla, California
| | - Chambers C Hughes
- Center for Marine Biotechnology and Biomedicine, Scripps Institution of Oceanography, University of California, La Jolla, California
| | - Mariam Betsiashvili
- Section of Cell and Developmental Biology, University of California, La Jolla, California
| | - Alisa Huffaker
- Section of Cell and Developmental Biology, University of California, La Jolla, California
| | - Eric A Schmelz
- Section of Cell and Developmental Biology, University of California, La Jolla, California
| | - Philipp Zerbe
- Department of Plant Biology, University of California, Davis, California
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Betsiashvili M, Ahern KR, Jander G. Additive effects of two quantitative trait loci that confer Rhopalosiphum maidis (corn leaf aphid) resistance in maize inbred line Mo17. J Exp Bot 2015; 66:571-8. [PMID: 25249072 PMCID: PMC4286405 DOI: 10.1093/jxb/eru379] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Plants show considerable within-species variation in their resistance to insect herbivores. In the case of Zea mays (cultivated maize), Rhopalosiphum maidis (corn leaf aphids) produce approximately twenty times more progeny on inbred line B73 than on inbred line Mo17. Genetic mapping of this difference in maize aphid resistance identified quantitative trait loci (QTL) on chromosomes 4 and 6, with the Mo17 allele reducing aphid reproduction in each case. The chromosome 4 QTL mapping interval includes several genes involved in the biosynthesis of DIMBOA (2,4-dihydroxy-7-methoxy-1,4-benzoxazin-3-one), a maize defensive metabolite that also is required for callose accumulation in response to aphid feeding. Consistent with the known association of callose with plant defence against aphids, R. maidis reproduction on B73×Mo17 recombinant inbred lines was negatively correlated with both DIMBOA content and callose formation. Further genetic mapping, as well as experiments with near-isogenic lines, confirmed that the Mo17 allele causes increased DIMBOA accumulation relative to the B73 allele. The chromosome 6 aphid resistance QTL functions independently of DIMBOA accumulation and has an effect that is additive to that of the chromosome 4 QTL. Thus, at least two separate defence mechanisms account for the higher level of R. maidis resistance in Mo17 compared with B73.
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Affiliation(s)
| | - Kevin R Ahern
- Boyce Thompson Institute for Plant Research, Ithaca, New York, 14853, USA
| | - Georg Jander
- Boyce Thompson Institute for Plant Research, Ithaca, New York, 14853, USA
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