Grant: Discovery Grants Program - Individual

I use a comparative approach to study the structure and developmental potential of meristems, which are regions of actively dividing cells in plants. Comparative developmental studies are used to elucidate patterns and develop testable hypotheses on how genetic pathways can be altered to lead to morphologically different forms. The central goal of my research program is to gain a better understanding of early developmental events at the level of meristems that lead to the form of mature plants organs using species that exhibit uncommon morphologies. My short-term objectives focus on studies dealing with homeosis in flowers. Homeosis refers to the growth of specific types of organs in sectors where they normally don't develop. I will study this phenomenon in two systems: Aroids (Araceae) and Hibiscus (Malvaceae). 1. Cylindrical inflorescences of Aroids: A number of Aroid species with cylindrical inflorescences consist of male flowers in the upper portion and females in the lower portion, as well as a sector of bisexual flowers between these two zones. These bisexual flowers represent a unique case of homeosis where female organs (aka carpels) are replaced by male organs (aka stamens) on the same whorl. 2. 'Double' flowers of Hibiscus: In Hibiscus rosa-sinensis, double flowers produce a number of stamens as well as petaloid floral organs on a donut-shaped meristematic ring normally designated exclusively for stamen production in typical flowers. In both systems, I want to determine if there are general relationships that characterize the substitution of one type of organ by another to uncover potential developmental constraints and underlying mechanisms. Additionally, I plan to identify floral organ identity gene homologues and their patterns fo expression during early stages of initiation and development. I also plan to use sequencing techniques to compare transcriptomes (gene expression profiles) of male, female, and atypical flowers in Aroids. 3. Real time morphogenesis technique development: Although developmental series of floral organs are reported in the literature, they are mainly based on an assemblage of several sequential 'static' developmental stages. There are very few studies that have attempted to document development in real time using a single meristem because of inherent limitations that prevent continuous track of morphogenesis without eliciting damage.  Preliminary work in our laboratory combining the micro culture of meristematic tissues and scanning electron microscopy shows great promise as a useful approach to capture and characterize the dynamic nature of the relationship between a meristem and the organs it forms. The main objective of this study will be to quantitatively analyze the relationships between the size of floral primordia and the size of inflorescence meristem in Aroids; similarly we will also analyze the size and shape of floral organs in relation to the size and shape of the floral meristem in Hibiscus.