We are studying the molecular basis and evolution of life-cycle transitions in the flagellated green soil alga, Chlamydomonas reinhardtii. We have cloned genes in the mating-type (MT) locus and genes regulated by MT that control the transitions between vegetative growth, gametic differentiation, and zygote development. These include genes responsible for gametic differentiation, mate recognition, and uniparental inheritance of chloroplast DNA, allowing us to study their function and their evolution during speciation. Of particular current interest are the homeoproteins Gsm1 and Gsp1 that heterodimerize upon gametic cell fusion, migrate to the nucleus, and activate the early diploid genetic program. These proteins share genetic ancestry with the Knox and Bell homeoprotein families that play key roles in determining cell fate in the land plants.
We have also recently initiated studies on lipid-body biogenesis in Chlamydomonas, the goal being to contribute to the international effort to produce algal biodiesel as a transportation fuel. We have found conditions that induce a 60-fold increase in triacylglycerol biosynthesis, and seek to identify the molecular pathways and environmental conditions involved in this stimulus, after which we will attempt to enhance production further via genetic manipulation