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Title: Genetic improvement of grass pea (Lathyrus sativus) for low β-L-ODAP content
Author: Emmrich, Peter
ISNI:       0000 0004 6351 173X
Awarding Body: University of East Anglia
Current Institution: University of East Anglia
Date of Award: 2017
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Grass pea (Lathyrus sativus) is a legume crop with great potential for global food security due to its exceptional tolerance to drought and flooding. The main limitation of this crop is the presence of the toxin β-L-oxalyl-2,3-diaminopropionic acid (β-L-ODAP) in its seeds and green tissues, which can cause paralysis in humans if grass pea is consumed over long periods. The objective of this study was to develop means to identify grass pea genotypes with reduced or zero seed β-L-ODAP content and to investigate the biosynthetic pathway of this compound in grass pea. To this end, collections of grass pea germplasm were screened for variation in seed β-L-ODAP levels. Considerable variation in β-L-ODAP levels was observed but no β-L-ODAP-free plants were identified. To increase the available variation for this trait, an EMS-mutagenised population was screened for low/zero-ODAP mutants. This mutant screen yielded 14 low-ODAP mutant lines, three of which were characterised using a mass spectrometry method, employing a stable-isotope-labelled isoform of β-L-ODAP as an internal standard. Both the development of the mass spectrometry method and the synthesis of the internal standard were performed for the purposes of this project. The three characterised lines yielded seed β-L-ODAP-contents below existing low-ODAP varieties, although none were β-L-ODAP-free. To further investigate the synthesis of β-L-ODAP, RNA was extracted from several tissues of grass pea and sequenced to create tissue specific transcriptomes. These were interrogated to identify candidate genes, which were tested using heterologous expression in Nicotiana benthamiana. One candidate gene of the BAHD-acyltransferase family was confirmed as an enzyme capable of catalysing the synthesis of β-L-ODAP. The identification of a set of low- ODAP mutants and the ODAP-synthase gene represent significant advances towards understanding the role of β-L-ODAP in grass pea and the development of grass pea genotypes free of this neurotoxin.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available