Radakovic, Zoran: Identification and characterisation of Heterodera schachtii susceptibility genes AtPANB1 and HIPP27 in Arabidopsis thaliana. - Bonn, 2018. - Dissertation, Rheinische Friedrich-Wilhelms-Universität Bonn.
Online-Ausgabe in bonndoc: https://nbn-resolving.org/urn:nbn:de:hbz:5n-52589
urn: https://nbn-resolving.org/urn:nbn:de:hbz:5n-52589,
author = {{Zoran Radakovic}},
title = {Identification and characterisation of Heterodera schachtii susceptibility genes AtPANB1 and HIPP27 in Arabidopsis thaliana},
school = {Rheinische Friedrich-Wilhelms-Universität Bonn},
year = 2018,
month = nov,

note = {Sedentary plant-parasitic cyst nematodes are obligate biotrophs that infect the roots of their host plant. Their parasitism is based on modification of infected root cells to form a hypermetabolic syncytium from which the nematodes draw their nutrients. The aim of this study was to identify nematode susceptibility genes in Arabidopsis thaliana and to characterize their roles in supporting the parasitism of Heterodera schachtii. By selecting genes that were most strongly upregulated in response to cyst nematode infection, we identified HIPP27 (Heavy metal-associated Isoprenylated Plant Protein 27) and AtPANB1 (3-methyl-2-oxobutanoate hydroxymethyltransferase 1) as host susceptibility factors required for cyst nematode infection. The role of HIPP27 and PANB1 was then characterized in detail during cyst nematode infection.
In A. thaliana, HIPPs make up the largest metallochaperone family, comprising 45 members divided into seven distinct classes. HIPPs are present only in vascular plants and are involved in a variety of biological processes, including heavy metal homeostasis and detoxification, transcriptional responses to abiotic stresses such as drought and cold, and plant–pathogen interactions. However, the mechanistic details underlying the roles of HIPPs in these biological processes has remained mostly unknown. Our detailed expression analysis using pHIPP27::GUS and pHIPP27:GFP lines revealed that HIPP27 is a cytoplasmic protein and that HIPP27 is strongly expressed in leaves, flowers, young roots and nematode-induced syncytia. Analysis of loss-of-function mutants and overexpression lines revealed that HIPP27 positively regulates the cyst nematode infection of host plants. Moreover, we found no difference in the activation of the reactive oxygen species (ROS) burst or in the expression of defence genes between Col-0 and hipp27 mutant lines. Based on these results, we hypothesized that expression of HIPP27 is required for maintaining the optimal development or functioning of the syncytium. Notably, microscopic observations confirmed that lack of HIPP27 protein causes physiological or metabolic abnormalities leading to the accumulation of phloem-provided polysaccharides such as starch grains in peridermal and syncytial plastids.
Vitamin B5 (VB5) is an essential nutritional factor that is synthesized via a three-step process in plants. In Arabidopsis, AtPANB1 and AtPANB2 encode the enzyme for
the first step and AtPANC the enzyme for the last step of the pathway. In comparison to plants, multicellular animals absorb VB5 from their diet. Our analysis showed that expression of AtPANB1 and AtPANB2 is strongly induced upon infection, and this upregulation is essential for nematode development. In comparison to AtPANB, AtPANC is not upregulated and does not play a role in parasitism. Notably, we identified a nematode PANC gene (HsPANC) and showed that the nematodes are able to perform the last step of VB5 biosynthesis using HsPANC. A detailed analysis revealed that compartmentalization of VB5 biosynthesis between plants and nematodes might be needed to avoid feedback/feed-forward inhibition and ensures a continuous supply of VB5 to rapidly developing nematodes. Altogether, our results suggest that HIPP27 and PANB1 are susceptibility genes in Arabidopsis whose loss-of-function reduces plant susceptibility to cyst nematode infection without increasing susceptibility to other pathogens or negatively affecting plant phenotype. These results have potential to improve breeding strategies for modern agriculture.},

url = {https://hdl.handle.net/20.500.11811/7377}

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