The CIN-TCP transcription factors promote commitment to differentiation in Arabidopsis leaf pavement cells via both auxin-dependent and independent pathways

Challa, Krishna Reddy and Rath, Monalisha and Nath, Utpal (2019) The CIN-TCP transcription factors promote commitment to differentiation in Arabidopsis leaf pavement cells via both auxin-dependent and independent pathways. In: PLOS GENETICS, 15 (2).

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Abstract

Cells in organ primordia undergo active proliferation at an early stage to generate sufficient number, before exiting proliferation and entering differentiation. However, how the actively proliferating cells are developmentally reprogrammed to acquire differentiation potential during organ maturation is unclear. Here, we induced a microRNA-resistant form of TCP4 at various developmental stages of Arabidopsis leaf primordium that lacked the activity of TCP4 and its homologues and followed its effect on growth kinematics. By combining this with spatio-temporal gene expression analysis, we show that TCP4 commits leaf cells within the transition zone to exit proliferation and enter differentiation. A 24-hour pulse of TCP4 activity was sufficient to impart irreversible differentiation competence to the actively dividing cells. A combination of biochemical and genetic analyses revealed that TCP4 imparts differentiation competence by promoting auxin response as well as by directly activating HAT2, a HD-ZIP II transcription factor-encoding gene that also acts downstream to auxin response. Our study offers a molecular link between the two major organ maturation factors, CIN-like TCPs and HD-ZIP II transcription factors and explains how TCP activity restricts the cell number and final size in a leaf. Author summary Cells in a young organ primordium proliferate to generate sufficient number, before they exit division cycle and enter differentiation programme at later stages. While factors that drive cell cycle progression have been identified and studied in detail in diverse eukaryotic species, developmental factors that promote exit from division and entry into differentiation are less known, especially in the plant kingdom. Here, we show that the class II TCP proteins, notably TCP4, irreversibly reprogram the mitotic cells to exit division and acquire differentiation competence by auxin response as well as direct activation of HAT2 transcription. Our work offers a molecular link between class II TCP and HD-ZIP II genes during the cell differentiation and leaf maturation.

Item Type:	Journal Article
Publication:	PLOS GENETICS
Publisher:	PUBLIC LIBRARY SCIENCE
Additional Information:	Copyright of this article belongs to PUBLIC LIBRARY SCIENCE
Department/Centre:	Division of Biological Sciences > Microbiology & Cell Biology
Date Deposited:	24 May 2019 11:28
Last Modified:	24 May 2019 11:28
URI:	http://eprints.iisc.ac.in/id/eprint/62437

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