Year: 2016
Type: dissertation
Abstract: Legumes underpin the global food network, providing the majority of the world’s dietary protein. \nHowever, global productivity of grain legumes is limited by environmental stresses, particularly \nchilling and freezing. For example, chilling temperatures (0-15 ºC) limit the production of soybean \n(Glycine max; a tropical legume), while extreme freezing temperatures (<0 ºC) limit use of temperate \nlegumes such as faba bean (Vicia faba L). The following studies were performed to gain new insights \ninto chilling and freezing tolerance in these two important legumes. Transgenic soybean lines, \noverexpressing the rice cysteine protease inhibitor, oryzacystatin I (OCI), showed decreased chillinginduced \ninhibition of photosynthesis compared to wild type (Wt). These lines also showed an \nincreased abundance of transcripts encoding the strigolactone (SL) biosynthesis enzymes: carotenoid \ncleavage dioxygenases 7 and 8 (CCD7, CCD8). Pea (rms3, rms4, rms5) and Arabidopsis thaliana \n(max2-1, max3-9, max4-1) mutants, deficient in SL synthesis and signalling, showed enhanced \nsensitivity to dark-chilling. Differences in chilling and freezing sensitivity were also identified in 5 \nfaba bean cultivars. Transcriptome profiling comparisons were performed on the most chilling \nsensitive (Wizard) and most chilling tolerant (Hiverna) cultivars to identify specific differences in \ngene expression, underpinning stress tolerance. Moreover, genome sequencing of the Wizard cultivar \nenabled the assembly and annotation of the mitochondrial and chloroplast genomes. Single nucleotide \npolymorphisms (SNP) were found in several organelle genes, when comparing read sequences to \npublished references. Furthermore, based on published SNP orientated linkage maps, contiguous read \nsequences could be mapped to chromosomal loci, leading to the identification of 8 putative nuclear \ngene sequences and an increase in sequence length data at 147 loci. Together with these new genomic \nresources, the discovery that cysteine proteases, phytocystatins and SL are important in legume low \ntemperature tolerance will enable the development of stress tolerance markers, for use in faba bean \nselective breeding programs.
Author: James W. Cooper
Language: English
Subfield: Plant Science
Domain: Life Sciences
SDG: Zero hunger
Open Access status: green
OpenAlex ID: W2593216476