Genome and Transcriptome Based Characterization of Low Phytate Soybean and Rsv3-Type Resistance to Soybean Mosaic Virus

Abstract

Soybean is a dominant oilseed cultivated worldwide for its use in multiple sectors such as food and feed industries, animal husbandry, cosmetics and pharmaceutical sectors, and more recently, in production of biodiesel. Increasing demand of soybean, changing environmental conditions, and evolution of pathogens pose challenges to soybean production in limited acreage. Genetic research is the key to ensure the continued growth in soybean production, with enhanced yield and quality, while reducing the losses due to diseases and pests. This research is focused on the understanding of transcriptional regulation of two economically important agronomic traits of soybean: low seed phytic acid and resistance to Soybean mosaic virus (SMV), using the 'transcriptomics' and 'genomics' approaches. The low phytic acid (lpa) soybean is more desirable than conventional soybean, as phytic acid is an anti-nutritional component of seed and is associated with phosphorus pollution. Despite the eco-friendly nature of the lpa soybean, it shows poor emergence, which reduces soybean yield. This research is mainly focused on addressing the impact of lpa-causing mutations on seed development, which is suspected to cause low emergence in lpa soybeans. The differences in transcriptome profiles of developing seeds in lpa and normal phytic acid soybean are revealed and the biological pathways that may potentially be involved in regulation of seed development are suggested. The second research project is focused on Rsv3-type resistance, which is effective against most virulent strains of Soybean mosaic virus. The Rsv3 locus, which maps on to soybean chromosome 14, contains 10 genes including a cluster of coiled coil-nucleotide binding-leucine rich repeat (CC-NB-LRR) protein-encoding genes. This dissertation employed a comparative sequencing approach to narrow down the list of Rsv3 gene candidates to the most promising CC-NB-LRR gene. The evidence provided in this study clearly indicates a single CC-NB-LRR gene as the most promising candidate to deliver Rsv3-type resistance.