Forging the path to plant resilience: CYCP4s at the crux of physiological and developmental response in Arabidopsis roots

Tomasi, Giuseppe (2024) Forging the path to plant resilience: CYCP4s at the crux of physiological and developmental response in Arabidopsis roots. Doctoral thesis, University of East Anglia.

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Abstract

Iron is an essential micronutrient critical to the growth and development of all living organisms. In plants, fluctuations in iron availability can significantly affect physiological processes, including root development and architecture. For instance, in Arabidopsis, it has been observed that phosphate-starved plants overaccumulate iron, which severely impacts root structures. This relationship underscores the complex interplay between iron and phosphate nutrients. Similar regulatory mechanisms have been documented in yeast, where the phosphate starvation pathway is governed by the PHO80 cyclin. This cyclin is homologous to the plant P-family cyclins (CYCPs), suggesting a conserved regulatory mechanism across species. In this study, I explored the role of CYCPs in Arabidopsis in response to iron starvation. Specifically, I conducted in vivo GUS transcriptional analysis of CYCP4;2 and CYCP4;3 by transferring seedlings to iron-deficient media after germination on iron-sufficient medium. Results indicate that both genes are ectopically expressed in a tissue-specific manner in the roots of iron-deficient seedlings, but never in the meristems, suggesting a non-mitotic role for CYCP4;2 and CYCP4;3 in modulating root tissue development in response to iron deficiency. Further investigations showed that overexpressing CYCP4;2 or CYCP4;3 in seedlings transferred to iron-depleted media resulted in reduced sensitivity to iron deficiency, as evidenced by longer roots and a higher density of lateral roots compared to wild-type plants. Conversely, CRISPR-Cas9-mediated editing of these genes led to shorter roots in CYCP4;2 knockdown plants but not in CYCP4;3, indicating that CYCP4;2 specifically is necessary and sufficient to modulate root length in response to iron deficiency. Transcriptomic analysis revealed that CYCP4;2 overexpression does not specifically influence the iron response but instead regulates genes responsible for a more generalised stress response. Altogether, these findings suggest that CYCP4;2 and CYCP4;3 are non-canonical cyclins that regulate not only the specific response to iron deficiency but also the broader plant stress response.

Item Type:	Thesis (Doctoral)
Faculty \ School:	Faculty of Science > School of Biological Sciences
Depositing User:	Kitty Laine
Date Deposited:	03 Jun 2025 09:33
Last Modified:	03 Jun 2025 09:33
URI:	https://ueaeprints.uea.ac.uk/id/eprint/99382
DOI:

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