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Sundkvist, Elsa, 2021. The role of PECTATE LYASE-LIKE genes in xylem development and vascular regeneration. Second cycle, A2E. Uppsala: SLU, Dept. Of Plant Biology

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When plant tissues are wounded the most important action for the plant’s survival is to heal the vascular strands to resume transport of water and nutrients. In addition to wound healing, the agricultural and horticultural practice of grafting, the joining of plant tissues from two individuals to form one, also requires the reconnection of vasculature over the graft junction. Similarities between regeneration and grafting have been found with leaf vein formation and hijacking of vasculature in parasitic interactions. Common traits in vascular formation are the activation of, or dedifferentiation to, cambium and the differentiation to xylem and phloem. Recently, RNAseq data from hypocotyl grafts in Arabidopsis thaliana showed considerable expression upregulation of members in the gene family PECTATE LYASE-LIKE (PLL) which encodes pectate lyases, enzymes involved in pectin degradation. Pectin is one of the main components of the cell wall and the middle lamella between plant cells. Cell wall degrading enzymes contribute to cell wall loosening and cell separation which is required for division, expansion and elongation of cells. The transcriptomics data points to the involvement of five PLL genes in vascular reconnection during grafting. However, their role in vascular differentiation and regeneration have not been further investigated. The aim of this thesis was to study the involvement of five PLLs with highly upregulated gene expression in the grafting data sets during vascular development, primarily xylem development, and vascular regeneration. Arabidopsis loss-of-function mutants of the five PLLs were analysed with various assays including root tip regeneration, cell wall enzyme assays, hypocotyl micrografting and VISUAL, a method for observing xylem development. Mutants of the genes PLL22 and PLL26 exhibited reduced xylem development in VISUAL whereas the regeneration and grafting experiments showed insignificant effects on vasculature in all pll mutants. The obtained results suggest PLL22 and PLL26 affects in vitro xylem development in cotyledons and that there is possibly redundancy between PLL genes during vascular regeneration.

Main title:The role of PECTATE LYASE-LIKE genes in xylem development and vascular regeneration
Authors:Sundkvist, Elsa
Supervisor:Melnyk, Charles
Examiner:Hofius, Daniel
Series:Examensarbete / Institutionen för växtbiologi, SLU
Volume/Sequential designation:191
Year of Publication:2021
Level and depth descriptor:Second cycle, A2E
Student's programme affiliation:SM006 Plant Biology for Sustainable Production - Master's programme, 120.0hp
Supervising department:(NL, NJ) > Dept. Of Plant Biology
Keywords:grafting, vascular development, regeneration, Pectate lyase, PLLs
Permanent URL:
Subject. Use of subject categories until 2023-04-30.:Plant genetics and breeding
Deposited On:20 Aug 2021 06:27
Metadata Last Modified:21 Aug 2021 01:03

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