Work in my lab focuses on dissecting molecular genetic mechanisms of flowering. Much of the work centers on the model system Arabidopsis, where we can utilize the many tools available, including genetic, biochemical and molecular approaches, to define the pathways involved in controlling the development of different reproductive structures. Our work in Arabidopsis then provides us with a framework within which we can assess how these developmental mechanisms have been modulated in other plant species; in turn, these comparative analyses have led to new hypotheses of the evolutionary history of these developmental processes.
Yale has an excellent plant molecular genetics/developmental biology group (in the Department of Molecular, Cellular and Developmental Biology); this is complemented by a thriving plant evolutionary biology group (in the Department of Ecology and Evolutionary Biology). I have a primary appointment in MCDB and a joint appointment in EEB, which has facilitated the development of several collaborations as well as coursework in evolutionary developmental biology. In collaboration with Dr. Gunter Wagner (EEB), I have developed a new course entitled Evolutionary Developmental Biology, aimed at senior undergraduates and first year graduate students. This course will focus on exposing students to approaches to phylogenetic analysis, the uses of the paleontological record, methodologies in developmental genetics, as well as examining selected examples in both plants and animals of how developmental pathways have been modulated over evolutionary time.
At the research level, we have been involved in assessing how changes in several key master regulatory genes may have led to changes in floral form in the angiosperms. We have focused on analyzing several MADS box genes that, in Arabidopsis, are required for the specification of floral organ identities. Our work has demonstrated that a major duplication event has occurred at the base of the core eudicots in several of these gene lineages that is correlated with the fixation of new floral traits in this clade (Kramer and Irish, 1998; Litt and Irish, 2002). Furthermore, expression analyses of these genes in various angiosperm species supports the hypothesis that these genes have acquired new functions concomitant with this major gene duplication (Kramer and Irish 1999; 2000). Together, these analyses have provided the basis for new models of how floral organ identity gene functions have arisen (Irish, 2000; 2001; 2002).