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ULTRAPETALA1 and LEAFY pathways function independently in specifying identity and determinacy at the Arabidopsis floral meristem

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† Background and Aims: The morphological variability of the flower in angiosperms, combined with its relatively simple structure, makes it an excellent model to study cell specification and the establishment of
morphogenetic patterns. Flowers are the products of floral meristems, which are determinate structures that generate four different types of floral organs before terminating. The precise organization of the flower in whorls, each defined by the identity and number of organs it contains, is controlled by a multi-layered network involving numerous transcriptional regulators. In particular, the AGAMOUS (AG) MADS domain-containing transcription factor plays a major role in controlling floral determinacy in Arabidopsis thaliana in addition to specifying reproductive organ identity. This study aims to characterize the genetic interactions between the ULTRAPETALA1 (ULT1) and LEAFY (LFY) transcriptional regulators during flower morphogenesis, with a
focus on AG regulation.

† Methods: Genetic and molecular approaches were used to address the question of redundancy and reciprocal interdependency for the establishment of flower meristem initiation, identity and termination. In particular, the effects of loss of both ULT1 and LFY function were determined by analysing flower developmental phenotypes of doublemutant plants. The dependency of each factor on the other for activating developmental genes was also investigated in gain-of-function experiments.

† Key Results The ULT1 and LFY pathways, while both activating AG expression in the centre of the flower meristem, functioned independently in floral meristem determinacy. Ectopic transcriptional activation by ULT1 of AG and AP3, another gene encoding a MADS domain-containing flower architect, did not depend on LFY function. Similarly, LFY did not require ULT1 function to ectopically determine floral fate.

†Conclusions The results indicate that the ULT1 and LFY pathways act separately in regulating identity and
determinacy at the floral meristem. In particular, they independently induce AG expression in the centre of the flower to terminate meristem activity. A model is proposed whereby these independent contributions bring
about a switch at the AG locus from an inactive to an active transcriptional state at the correct time and place during flower development.

Key words: Organogenesis, flower meristem identity, flower morphogenesis, flower determinacy, flower
development, Arabidopsis thaliana, activation of transcription, ULTRAPETALA1, ULT1, LEAFY, LFY, MADS
domain-containing proteins, AGAMOUS, trithorax group, trxG, chromatin.

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Informasi Detail

Judul Seri

Annals of Botany

No. Panggil

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Penerbit

Oxford : Oxford University Press on behalf of the Annals of Botany Company., 2014

Deskripsi Fisik

Annals of Botany 114: 1497–1505, 2014

Bahasa

English

ISBN/ISSN

doi:10.1093/aob/mcu1

Klasifikasi

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Tipe Isi

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Tipe Media

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Tipe Pembawa

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Edisi

114: 2014

Subjek

PERTANIAN.
ILMU GULMA

Info Detail Spesifik

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Pernyataan Tanggungjawab

agus

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Lampiran Berkas

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