Molecular and developmental biology; plant gene expression
107 Dorsheimer Laboratory and Greenhouse
Buffalo NY, 14260
Phone: (716) 645-4997
Bio 329, Genetics Lab
This is an upper division undergraduate laboratory course that covers advanced methods of genetic analysis, including mutagenesis, DNA cloning, DNA sequencing and analysis, genetic complementation, polymerase chain reaction, and CRISPR gene editing.
Bio 367 Developmental Biology
This is an undergraduate course in which covers aspects of molecular biology and gene expression that control development in animals and plants.
Bio 370 Developmental Biology Lab
This is an upper division undergraduate laboratory course that allows students to learn advanced laboratory methods used to study development in a variety of eukaryotic organisms, including plants, invertebrates, and vertebrates. Techniques covered include RNAi in invertebrates, microinjection of morpholinos for transient inactivation of gene expression in zebrafish embryos, viral effects on RNAi, use of reporter genes, production of transgenic plants, and immunolocalization with Laser Scanning Confocal microscopy.
Our main research project is photosynthetic gene expression in C4 plants
Rubisco: Our research is focused on the expression of genes that encode Ribulose 1,5-bisphophate carboxylase/oxygenase (abbreviated as Rubisco) in plants that utilize the highly efficient C pathway of photosynthesis. Rubisco is the principle enzyme of photosynthetic carbon fixation in all plants, and is central to their viability, growth, and productivity. Located within the chloroplasts, it consists of eight large (LSU) and eight small (SSU) subunits. The rbcL gene encoding the LSU is transcribed and translated within the chloroplasts. The SSU, encoded by a nuclear RbcS gene family, is translated on cytoplasmic ribosomes as a precursor that is transported into the chloroplasts. Within chloroplasts, the two subunits combine to form the functional LS Rubisco holoenzyme.
C Photosynthesis: Plants that use the C pathway of photosynthesis (C plants) have much higher rates of photosynthetic productivity than plants that utilize the more common and less efficient Cpathway (C plants). C plants account for about a fourth of the primary productivity of earth’s biosphere, and yet only about 5% of terrestrial plant species actually use this pathway for photosynthetic carbon fixation. In addition to increased productivity, advantages associated with C4 photosynthesis include greater water use efficiency, enhanced nitrogen-use efficiency, and increased adaptability to marginal environments. These advantages allow C plants to thrive in areas of high temperature and/or low water availability, where the viability of C plants can be severely limited. The C pathway occurs across a wide variety of plant species and has evolved independently many times.
C photosynthesis incorporates novel leaf anatomy, metabolic specializations, and modified gene expression. C plants typically possess a distinctive Kranz (or wreath) leaf anatomy that consists of two morphologically and functionally distinct photosynthetic cell types, the bundle sheath (BS) and mesophyll (M) cells. Within M cells, C species utilize phosphoenolpyruvate carboxylase (PEPCase) as the initial primary CO fixation enzyme leading to the production of C acids in a first stage of photosynthetic reactions. In a second stage that occurs only in BS cells, decarboxylation of the C acids releases CO, followed by the subsequent re-fixation of released CO by Rubisco (Calvin-Benson cycle). By separating these two photosynthetic stages, and partitioning Rubisco specifically within BS cells, C plants reduce or eliminate the photosynthetically wasteful reactions of photorespiration, thereby greatly enhancing their CO fixation ability.
An RNA binding protein that regulates Rubisco gene expression in C4 and C3 plants: In spite of the clearly defined biological parameters and advantages associated with C4 plants, molecular mechanisms responsible for C versus C photosynthetic gene expression patterns have remained highly elusive for many years. We have recently isolated a novel mRNA binding protein, the RBCL RNA S1-BINDING DOMAIN protein (RLSB), from chloroplasts of a C plant. This protein, encoded by the nuclear RLSB gene, is present and highly conserved among a wide variety of plant species. Co-localized with LSU to chloroplasts, RLSB is highly conserved across many plant species. Most significantly, RLSB localizes specifically to the Rubisco-containing BS cells in the leaves of C plants. Comparative functional analysis using maize (a C plant) and Arabidopsis (a C plant) reveals its tight association with rbcL gene expression in both species.
Our current findings indicate that specific binding of RLSB to rbcL mRNA and associated activation of rbcL gene expression within BS chloroplasts may be one determinant leading to the characteristic cell type-specific localization of Rubisco in C plants. Evolutionary modification of RLSB expression, from a C “default” state to BS cell-specificity, may represent one mechanism by which rbcL expression has become restricted to only one cell type in C plants.
Agricultural significance: Our ongoing research seeks to understand the mechanisms by which RLSB regulates the expression of rbcL gene expression in chloroplasts. Ultimately, regulatory processes such as this underlie the cell-type specific patterns of gene expression, the enhanced photosynthetic capabilities, and the environmental adaptability that characterize C plants. By integrating the use of advanced molecular biology and biochemistry methods, together with transgenic plants, state-of-the art confocal microscopy, and advanced genetic tools, we are uncovering exciting new insights into the molecular basis of C photosynthesis. This research has exciting prospects for agricultural development. Ultimately, our research may determine if the exploitation of RLSB can be used to enhance photosynthetic efficiency, thereby increasing biomass productivity of maize and other vital crop plants used for the production and food and biofuel.
Collaborative projects: The many experimental tools and multiple levels of analysis developed and used in our laboratory have been applied to a number of collaborative projects. Our most recent collaboration resulted in a series of studies to determine the effects of agricultural antibiotic wastes on plant viability, and the possible use of some plants for natural soil remediation to eliminate such contaminants (with Diana Aga, Dept. of Chemistry, UB). We have also contributed to studies on plant-virus interactions using Cucumber Mosiac Virus (CMV) (with John Carr, Dept. of Plant Sciences, Univ. of Cambridge, UK), Nitrate transporter genes (with LiPing Yin, Capital Normal University, Beijing), Regeneration in plant tissue culture (with Minesh Patel), and a novel regulator of chloroplast gene expression in response to plant stress (with V.J. Hernandez, formerly of the UB Dept. of Microbiology).