Beyond flowering time: diverse roles of an APETALA2-like transcription factor in shoot architecture and perennial traits.

Yanhao Zhou,Natanael Viñegra De La Torre,Maria C Albani,Xiangchao Gan,Ulla Neumann

doi:10.1111/nph.16839

Yanhao Zhou, Natanael Viñegra De La Torre + Show 3 more

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https://doi.org/10.1111/nph.16839

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Abstract

Polycarpic perennials maintain vegetative growth after flowering. PERPETUAL FLOWERING 1 (PEP1), the orthologue of FLOWERING LOCUS C (FLC) in Arabis alpina regulates flowering and contributes to polycarpy in a vernalisation-dependent pathway. pep1 mutants do not require vernalisation to flower and have reduced return to vegetative growth as all of their axillary branches become reproductive. To identify additional genes that regulate flowering and contribute to perennial traits we performed an enhancer screen of pep1. Using mapping-by-sequencing, we cloned a mutant (enhancer of pep1-055, eop055), performed transcriptome analysis and physiologically characterised the role it plays on perennial traits in an introgression line carrying the eop055 mutation and a functional PEP1 wild-type allele. eop055 flowers earlier than pep1 and carries a lesion in the A.alpina orthologue of the APETALA2 (AP2)-like gene, TARGET OF EAT2 (AaTOE2). AaTOE2 is a floral repressor and acts upstream of SQUAMOSA PROMOTER-BINDING PROTEIN-LIKE 5 (AaSPL5). In the wild-type background, which requires cold treatment to flower, AaTOE2 regulates the age-dependent response to vernalisation. In addition, AaTOE2 ensures the maintenance of vegetative growth by delaying axillary meristem initiation and repressing flowering of axillary buds before and during cold exposure. We conclude that AaTOE2 is instrumental in fine tuning different developmental traits in the perennial life cycle of A.alpina.

Highlights

Plants have evolved different life history strategies
Our experiments have previously demonstrated that the pep1-1 mutant still responds to different durations of vernalisation, suggesting that there are other repressors regulating flowering in parallel with PERPETUAL FLOWERING 1 (PEP1) (Lazaro et al, 2018)
We have previously shown that shoot architecture in A. alpina is organised in zones of differential bud activity and fate according to position on the plant named as V1, V2 and V3 (Lazaro et al, 2018; Vayssieres et al, 2020)

Summary

Introduction

Annuals are monocarpic and set seed and senesce after flowering. Most perennials are polycarpic, being able to maintain vegetative growth from axillary meristems (AMs) and restricting senescence only to the reproductive branches (Amasino, 2009; Albani & Coupland, 2010). The polycarpic behaviour of perennial plants is a result of the asynchronous and differential behaviour of AMs as some commit to reproductive development, while others develop into vegetative branches or arrest growth after producing a few leaves and forming a bud (Tan & Swain, 2006; Costes et al, 2014; Park et al, 2017; Vayssieres et al, 2020). Understanding the molecular mechanisms underlying the activity and fate of AMs can give insight into plant life history evolution

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