The role of plasmodesmata in the growth-defence trade-off

Raven, Emma (2024) The role of plasmodesmata in the growth-defence trade-off. Doctoral thesis, University of East Anglia.

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Abstract

Plasmodesmata are plasma membrane-lined channels that connect adjacent plant cells to form a symplasmic network. These channels play a key role in both defence against pathogens and the phloem unloading of sugars. In mature leaf tissue, plasmodesmal closure is triggered upon detection of pathogen-associated molecular patterns (PAMPs), reducing cell-to-cell movement of molecules. In this thesis, I find PAMPs do not induce plasmodesmal closure in young Arabidopsis sink leaves. Other stress-related elicitors, such as hydrogen peroxide, salicylic acid, and abscisic acid also do not induce plasmodesmal closure in young sink leaves. Additionally, I find inducing the sink-source transition in young leaves changes plasmodesmal PAMP response. Young source leaves show PAMP-induced plasmodesmal closure, whilst young sink leaves do not. This indicates the change in PAMP response between young sink and mature source leaves is related to the sink-source status of the leaf rather than leaf age. I hypothesise the importance of plasmodesmata in symplastic phloem-unloading underpins this change in plasmodesmal stress response across the sink-source transition. Using lines with inducible plasmodesmal closure, I show that inducing plasmodesmal closure in young leaves and roots reduces phloem unloading and growth. Thus the regulation of plasmodesmal permeability in young sink tissue may be dependent on the balancing of a trade-off between growth and defence. Additionally, I find structure does not change across the sink-to-source transition meaning structure cannot account for changes to plasmodesmal response across the sink-source transition. Overall, these results suggest plasmodesmal response to PAMPs is dependent on the sink-source transition, highlighting the importance of maintaining symplastic connectivity in sink tissues.

Item Type:	Thesis (Doctoral)
Faculty \ School:	Faculty of Science > School of Biological Sciences
Depositing User:	Chris White
Date Deposited:	08 Jan 2025 11:23
Last Modified:	08 Jan 2025 11:23
URI:	https://ueaeprints.uea.ac.uk/id/eprint/98115
DOI:

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