Physiology and Molecular Evolution of Photoprotection in Allopolyploids

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Polyploidy is the multiplication of the entire genome beyond the diploid level. It is a particularly important genetic process in flowering plants, and many cultivated plants (e.g., wheat, maize, cotton, soybean) are polyploid. Polyploidy can lead to profound genomic changes, even beyond duplicating all of the genes in the genome. Polyploidy has long been known to affect physiology, anatomy, and biochemistry, but few studies have sought to connect phenotype with changes at the molecular level to understand how plants achieve an integrated response to polyploidy in natural populations. Such investigations hold the key to understanding why polyploids are so prevalent among plants, and why polyploids often have been considered more adaptable or more successful than their diploid progenitors.This project will study photoprotection - an important physiological process by which plants avoid damage from excess light energy - in several recently formed polyploid species of Glycine, the genus that includes the cultivated soybean. These species formed by hybridization and genome doubling (allopolyploidy) within the last 50,000 years. The diploid species that gave rise to them have been identified. Chlorophyll fluorescence assays will be used to compare photoprotection in the polyploid species with their diploid progenitors. At the molecular level, it will be determined how the gene copies contributed by the two diploid progenitors have changed in sequence and expression in the polyploidy species since their formation, and whether changes in DNA sequence, dosage, and/or expression patterns correlate with photoprotection phenotype.Broader Impacts. This project is of broad significance and impact because it will elucidate the effects of a ubiquitous genetic phenomenon, polyploidy, on a physiological process essential to plant fitness, and will connect this to changes in the genes underlying photoprotection. In addition, the project involves training graduate and undergraduate students and is linked to an ongoing high-school teacher outreach program at Cornell.