My interests are in ecosystem ecology. I use remote-sensing to map vegetation characteristics such as cover, biomass, and functional-type aggregations. Then I study their patterns in relation to the environment. I like to explore how ecological relationships change across spatial scales from regional to continental. My PhD research at Colorado State University focused on woody vegetation in African savannas. Currently, I am working with Dr. Brian Beckage on the temporal and spatial dynamics of tropical hardwood hammocks within pine savannas in the Everglades National Park, Florida. My objective is to study the interactions between pines and hardwoods mediated by fire, flooding and frost. There is a need for quantitative information on these dynamics. For this purpose, I use aerial photographs acquired in the last 50 years to assess hardwood hammocks ‘ spatial extent and model temporal variation as a function of environmental factors.
Vikram is interested in understanding how environment shapes the genetic structure and geographical trajectory of tree populations over evolutionary time scales. He is currently working with Steve on understanding climate adaptation in balsam poplar (Populus balsamifera). Vikram is fascinated by long lived trees such as the redwood, douglas fir and particularly bristlecone pines. In the past he has studied the genetics of Norway spruce from northern Sweden, Teakwood from peninsular India, eastern white pine from northern Ontario and loblolly pine from the southeastern United States. In his free time, Vikram enjoys cycling, traveling and visiting national parks.
Investigating the Role of the LATD/NIP Gene in Root Architecture, Nodulation and ABA Signaling in Legume Medicago truncatula
Christine Ondzighi-Assoume and Jeanne M. Harris*
University of Vermont, Burlington, VT 05405, USA. *Principal Investigator
In the Dr. Jeanne M. Harris lab, the goal of my postdoctoral work is to understand the molecular and cellular mechanisms that govern legume root and nodule formation in the view to enhance plants growth. I specifically aim to investigate the role of the LATD/NIP gene in root architecture, nodulation and ABA signaling in legume Medicago truncatula.
The formation of the root organ is a crucial event for the growth of any plant. Legume root architecture involves both the elaboration of the root system by the formation of primary and lateral roots and also the formation of symbiotic root nodules in association with nitrogen-fixing soil rhizobium bacteria. The Medicago truncatula LATD/NIP gene was found to encode a putative nitrate transporter that is required for the growth of both primary and lateral roots as well as symbiotic root nodules. My project goal is to understand the molecular and cellular functions of LATD/NIP that control legume root and nodule formation in the view to enhance plants growth. I specifically aim to investigate the connection between the LATD/NIP transporter and the role of ABA transport in root system development by addressing these specific questions: What is the molecular function of the LATD/NIP product? Where is it localized in the plant and in the cell? Are there homologs in non-legumes? Finally, what is the relationship of the LATD/NIP gene to the evolution of nodulation? To answer these questions, I will utilize molecular genetics, biochemical and cell biological tools using Medicago truncatula and Arabidopsis thaliana plants.
In addition of enjoying doing plant science, I also like having fun dancing with the pigeons/doves in downtown Paris during summer time.
My research is focused on the evolution and systematics of tropical ferns and lycophytes. Currently I am working on an analysis of relationships within the grammitid ferns (Polypodiaceae), using molecular, and morphological data, in collaboration with Tom Ranker (National Science Foundation), Cliff Morden (University of Hawaii, Manoa) and Barbara Parris. Grammitids are a clade of about 900 primarily epiphytic species that display a wide range of morphological variation. These phylogenies will be used for the study of character evolution, and to resolve the circumscription of genera, which has been problematic.
I am also contributing to a world-wide monograph and phylogeny of Megalastrum (Dryopteridaceae) with collaborators Robbin Moran (The New York Botanical Garden), Jefferson Prado Instituto de Botánica São Paulo, Brazi), Paulo Labiak (Universidade Federal do Paraná, Brazil), and Germinal Rouhan (Muséum National d'Histoire Naturelle, Herbier National, Paris), which can be viewed at http://sweetgum.nybg.org/megalastrum/index.php. In conjunction with this project, we are working on relationships and morphological evolution in the Lastreid ferns, to which Megalastrum belongs.
I also contribute to regional floristic treatments, particularly in Bolivia, where I have been collaborating with Alan Smith (University of California, Berkeley Herbarium), Michael Kessler (University of Zurich), and Michael Nee (The New York Botanical Garden). This effort has led to the recent publication of Flora de la Region del Parque Nacional Amboró, vol. 1 Licofitas y Helechos, which treats nearly one half of the species known to occur in the country http://www.nybg.org/botany/nee/.
My duties at UVM include curation and development of both the Pringle Herbarium, and the Tryon Pteridophyte Library, which can be viewed here and here. I also maintain a photo blog of ferns and lycophytes with Nathan Smith (Instituto Nacional de Pesquisas da Amazônia), which can be viewed here.