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Cone‐setting in spruce is regulated by conserved elements of the age‐dependent flowering pathway

Authors :
Shirin Akhter
Karl Johan Westrin
Nathan Zivi
Veronika Nordal
Warren W. Kretzschmar
Nicolas Delhomme
Nathaniel R. Street
Ove Nilsson
Olof Emanuelsson
Jens F. Sundström
Source :
New Phytologist. 236:1951-1963
Publication Year :
2022
Publisher :
Wiley, 2022.

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.

Details

ISSN :
14698137 and 0028646X
Volume :
236
Database :
OpenAIRE
Journal :
New Phytologist
Accession number :
edsair.doi.dedup.....5555c4573432355e46d8866ddd2ab53b
Full Text :
https://doi.org/10.1111/nph.18449