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Xiong W, Berke L, Michelmore R, van Workum DJM, Becker FFM, Schijlen E, Bakker LV, Peters S, van Treuren R, Jeuken M, Bouwmeester K, Schranz ME. The genome of Lactuca saligna, a wild relative of lettuce, provides insight into non-host resistance to the downy mildew Bremia lactucae. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2023; 115:108-126. [PMID: 36987839 DOI: 10.1111/tpj.16212] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/29/2022] [Revised: 02/20/2023] [Accepted: 02/27/2023] [Indexed: 06/19/2023]
Abstract
Lactuca saligna L. is a wild relative of cultivated lettuce (Lactuca sativa L.), with which it is partially interfertile. Hybrid progeny suffer from hybrid incompatibility (HI), resulting in reduced fertility and distorted transmission ratios. Lactuca saligna displays broad-spectrum resistance against lettuce downy mildew caused by Bremia lactucae Regel and is considered a non-host species. This phenomenon of resistance in L. saligna is called non-host resistance (NHR). One possible mechanism behind this NHR is through the plant-pathogen interaction triggered by pathogen recognition receptors, including nucleotide-binding leucine-rich repeat (NLR) proteins and receptor-like kinases (RLKs). We report a chromosome-level genome assembly of L. saligna (accession CGN05327), leading to the identification of two large paracentric inversions (>50 Mb) between L. saligna and L. sativa. Genome-wide searches delineated the major resistance clusters as regions enriched in NLRs and RLKs. Three of the enriched regions co-locate with previously identified NHR intervals. RNA-seq analysis of Bremia-infected lettuce identified several differentially expressed RLKs in NHR regions. Three tandem wall-associated kinase-encoding genes (WAKs) in the NHR8 interval display particularly high expression changes at an early stage of infection. We propose RLKs as strong candidates for determinants of the NHR phenotype of L. saligna.
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Affiliation(s)
- Wei Xiong
- Biosystematics Group, Wageningen University and Research, Wageningen, The Netherlands
| | - Lidija Berke
- Biosystematics Group, Wageningen University and Research, Wageningen, The Netherlands
| | - Richard Michelmore
- Genome Center and Department of Plant Sciences, University of California, Davis, CA, USA
| | | | - Frank F M Becker
- Biosystematics Group, Wageningen University and Research, Wageningen, The Netherlands
| | - Elio Schijlen
- Bioscience, Wageningen University and Research, Wageningen, The Netherlands
| | - Linda V Bakker
- Bioscience, Wageningen University and Research, Wageningen, The Netherlands
| | - Sander Peters
- Bioscience, Wageningen University and Research, Wageningen, The Netherlands
| | - Rob van Treuren
- Centre for Genetic Resources, The Netherlands (CGN), Wageningen University and Research, Wageningen, The Netherlands
| | - Marieke Jeuken
- Plant Breeding, Wageningen University and Research, Wageningen, The Netherlands
| | - Klaas Bouwmeester
- Biosystematics Group, Wageningen University and Research, Wageningen, The Netherlands
| | - M Eric Schranz
- Biosystematics Group, Wageningen University and Research, Wageningen, The Netherlands
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