# Genetic regulation of a developmental clock in Arabidopsis

> **NIH NIH R01** · UNIVERSITY OF PENNSYLVANIA · 2020 · $338,100

## Abstract

ABSTRACT
Higher animals and plants undergo a process of developmental maturation following embryogenesis. This
process involves simultaneous changes in many different organs and tissues, which must be temporally
coordinated if the organism is to develop properly. Coordination between the maturation of non-reproductive
organs and the maturation of the reproductive system is particularly important because variation in the
relative timing of these processes can have serious consequences for the health and well-being of an
organism, and for its ability to reproduce. During its development, a plant shoot transitions from a juvenile to
an adult pattern of vegetative development (vegetative phase change), and becomes competent to produce
flowers. In Arabidopsis thaliana, vegetative phase change is regulated by a decrease in the level of miR156
and the consequent increase in the expression its targets, SPL transcription factors, which promote adult
vegetative traits. It is thought that this vegetative transition is linked to the acquisition of reproductive
competence through the effect of SPL proteins on the expression of MIR172B. However, there is evidence
that reproductive competence may actually be regulated by transcription factors that operate in parallel to
the MIR156 -| SPL -> MIR172B pathway. This hypothesis will be tested by examining the effect of
mutations in these transcription factors on the ability of the shoot to respond to a brief floral inductive
stimulus. Recent results suggest that the evolutionarily conserved chromatin remodeler, PICKLE, (PKL) is a
key component of the mechanism that coordinates the timing of vegetative phase change and reproductive
competence. PKL promotes the transcriptional repression of MIR156A/C by promoting the deposition of the
repressive histone mark, H3K27me3, at these genes. The molecular mechanism of this process will be
investigated by determining if PKL promotes histone deacetylation, and if it promotes the binding of proteins
involved in the deposition of H3K37me3 to MIR156A/C. Site-directed mutagenesis will be used to identify
sequences required for the temporal expression of MIR156C. Finally, the degree to which the timing of
vegetative phase change and reproductive competence vary naturally will be determined by measuring
these traits in 150 genome-sequenced accessions of A. thaliana from around the world. Loci responsible for
variation in the timing of vegetative phase change will be mapped in a subset of these accessions using
Traffic Lines. These experiments will answer long-standing questions about the genetic regulation of shoot
maturation, and will provide new insights into the molecular mechanism of this process and its role in the
evolution of A. thaliana.

## Key facts

- **NIH application ID:** 9912769
- **Project number:** 5R01GM051893-23
- **Recipient organization:** UNIVERSITY OF PENNSYLVANIA
- **Principal Investigator:** Richard Scott Poethig
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2020
- **Award amount:** $338,100
- **Award type:** 5
- **Project period:** 1995-01-01 → 2021-04-30

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/9912769

## Citation

> US National Institutes of Health, RePORTER application 9912769, Genetic regulation of a developmental clock in Arabidopsis (5R01GM051893-23). Retrieved via AI Analytics 2026-05-25 from https://api.ai-analytics.org/grant/nih/9912769. Licensed CC0.

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