The cyclin L homolog MOS12 and the MOS4-associated complex are required for the proper splicing of plant resistance genes

Authors

  • Fang Xu,

    1. Michael Smith Laboratories, University of British Columbia, Vancouver, BC V6T 1Z4, Canada
    2. Department of Botany, University of British Columbia, Vancouver, BC V6T 1Z4, Canada
    3. National Institute of Biological Sciences, Beijing 102206, China
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  • Shaohua Xu,

    1. National Institute of Biological Sciences, Beijing 102206, China
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  • Marcel Wiermer,

    1. Michael Smith Laboratories, University of British Columbia, Vancouver, BC V6T 1Z4, Canada
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    • Present address: Department of Plant Cell Biology, Albrecht-von-Haller-Institute for Plant Sciences, Georg-August-University Göttingen, Julia-Lermontowa-Weg 3, 37077 Göttingen, Germany.

  • Yuelin Zhang,

    1. Department of Botany, University of British Columbia, Vancouver, BC V6T 1Z4, Canada
    2. National Institute of Biological Sciences, Beijing 102206, China
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  • Xin Li

    Corresponding author
    1. Michael Smith Laboratories, University of British Columbia, Vancouver, BC V6T 1Z4, Canada
    2. Department of Botany, University of British Columbia, Vancouver, BC V6T 1Z4, Canada
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(e-mail xinli@interchange.ubc.ca).

Summary

Plant resistance (R) proteins protect cells from infections through recognizing effector molecules produced by pathogens and initiating downstream defense cascades. To mount proper immune responses, the expression of R genes has to be tightly controlled transcriptionally and post-transcriptionally. Intriguingly, alternative splicing of the genes of the nucleotide binding leucine-rich repeat (NB-LRR) type was observed in different plant species, but its regulatory mechanism remains elusive. Here, we report the positional cloning and functional analysis of modifier of snc1,12 (mos12-1), a partial loss-of-function mutant that can suppress the constitutive defense responses conferred by the gain-of-function R gene mutant suppressor of npr1-1 constitutive 1 (snc1). MOS12 encodes an arginine-rich protein that is homologous to human cyclin L. A null allele of mos12-2 is lethal, suggesting it has a vital role in plant growth and development. MOS12 localizes to the nucleus, and the mos12-1 mutation results in altered splicing patterns of SNC1 and RPS4, indicating that MOS12 is required for the proper splicing of target genes. MOS12 co-immunoprecipitates with MOS4, indicating that MOS12 associates with the MOS4-associated complex (MAC). Accordingly, splicing patterns of SNC1 and RPS4 are changed in most MAC core mutants. Our study highlights the contribution of MOS12 and the MAC in the alternative splicing of R genes, providing regulatory details on how alternative splicing is used to fine-tune gene expression in plant immunity.

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