Abstract

Reproductive phase change is well characterized in angiosperm model species, but less studied in gymnosperms. We utilize the early cone-setting acrocona mutant to study reproductive phase change in the conifer Picea abies (Norway spruce), a gymnosperm. The acrocona mutant frequently initiates cone-like structures, called transition shoots, in positions where wild-type P. abies always produces vegetative shoots. We collect acrocona and wild-type samples, and RNA-sequence their messenger RNA (mRNA) and microRNA (miRNA) fractions. We establish gene expression patterns and then use allele-specific transcript assembly to identify mutations in acrocona. We genotype a segregating population of inbred acrocona trees. A member of the SQUAMOSA BINDING PROTEIN-LIKE (SPL) gene family, PaSPL1, is active in reproductive meristems, whereas two putative negative regulators of PaSPL1, miRNA156 and the conifer specific miRNA529, are upregulated in vegetative and transition shoot meristems. We identify a mutation in a putative miRNA156/529 binding site of the acrocona PaSPL1 allele and show that the mutation renders the acrocona allele tolerant to these miRNAs. We show co-segregation between the early cone-setting phenotype and trees homozygous for the acrocona mutation. In conclusion, we demonstrate evolutionary conservation of the age-dependent flowering pathway and involvement of this pathway in regulating reproductive phase change in the conifer P. abies.

Keywords

cone-setting; flowering; gymnosperm; Picea abies; reproductive development; SPL-gene family; transcriptome

Published in

New Phytologist
2022, Volume: 236, number: 5, pages: 1951-1963
Publisher: WILEY

SLU Authors

• Akhter, Shirin

  • Department of Plant Biology, Swedish University of Agricultural Sciences
    

• Zivi, Nathan

  • Department of Plant Biology, Swedish University of Agricultural Sciences
    
  • Forestry Research Institute of Sweden, Skogforsk

• Nordal, Veronika

  • Department of Plant Biology, Swedish University of Agricultural Sciences
    

• Delhomme, Nicolas

  • Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences
    

• Nilsson, Ove

  • Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences
    

• Sundström, Jens

  • Department of Plant Biology, Swedish University of Agricultural Sciences
    

UKÄ Subject classification

Forest Science


Publication identifier

DOI: https://doi.org/10.1111/nph.18449

Permanent link to this page (URI)

https://res.slu.se/id/publ/119203