DISSERTATION RESEARCH: Phylogeny and evolutionary exploration of the C3-CAM phenotypic space in Calandrinia (Montiaceae)

Brown University, Providence RI

Investigators

Abstract

Crassulacean Acid Metabolism (CAM) photosynthesis is a complex set of traits that improves water use and photosynthetic efficiency in plants under drought and temperature stress. Calandrinia (Montiaceae) is an ideal lineage in which to investigate the evolutionary assembly of CAM photosynthesis. This research integrates phylogenetics, anatomy, ecology, physiology, greenhouse experiments, and gene expression studies to unravel the incremental assembly of CAM photosynthesis in Calandrinia. In light of ongoing global change and the increasing acidification of the global landscape (~40% of terrestrial Earth is already considered arid, semi-arid or sub-humid), CAM photosynthesis will likely play an important role in the future of carbon sequestration, sustainable biomass production, and food-crop security. With such imminent change ahead, it is more important than ever that we understand the evolutionary underpinnings of CAM photosynthesis, which may guide current efforts to engineer this syndrome into food and biofuel crops. The researchers will conduct a comparative gene expression study across species that represent C3, CAM, and CAM-intermediate types. They will use a comparative transcriptomic approach to answer the following questions: 1) how does differential gene expression of key CAM genes vary across the potentially intermediate types, 2) which gene copies are being recruited into new CAM function, 3) are there parallel nucleotide/ amino acid changes in gene copies recruited to perform CAM, and 4) how can transcriptome data help us to better differentiate and define these C3-CAM intermediates? Results from this study will yield the first lineage-based model of CAM evolution.