Biology Harvard University, 1975 B.S. Botany University of California, Davis, 1967 The Feldman Lab broadly researches plant development, with an emphasis on roots and the root meristem, including the root cap. We have focused much of our work on a population of cells known as the quiescent center and have shown that many of its activities and characteristics are related to redox status. For this effort we have developed a redox-sensing GFP which allows us to measure, in real time, redox status. We hypothesize that many of the profound effects and controls of auxin on root development are associated with changes in redox status. We also use microarrays to characterize distinct root meristem populations, including the root cap, in which we study gravity signal transduction.

May 18, 2009 - Institute of Plant Breeding, Genetics & Genomics. Buchanan et al. Biochemistry & Molecular Biology of Plants. American Society of. 12.4 Molecular Cloning and Analyses of an NOS-Like Gene of Pea 181 12.5 Correlation Study of NOS-Like Gene Expression and NOS Activity in Compatible and Incompatible Pea–Bacteria Interactions 184 References 185 13 Posttranslational Modifications of Proteins by Nitric Oxide: A New Tool of Metabolome Regulation 189.

A major goal of all of our work is to link molecular changes with biochemistry. A second major emphasis involves developing biosensors to allow plants to act as reporters of their own physiological status.

We have focused on the development of biosensors for heat stress. Our long term goal is to improve crop yield by having the plant 'tell' us when it needs some alteration of its growing conditions (for example, cooler temperatures, or water), before it experiences stress, and thus reduction in yield. Regulation of development in meristems/stem cells; Root gravitropism; redox regulation of plant development. Our lab's interests are in the area of plant development, with an emphasis on meristems, particularly those of roots.

We are investigating how the various populations of cells which comprise or surround the meristem interact to control root development, especially patterning. Gta san andreas download. Much of our recent effort has focused on two populations of cells: the root cap, and a region of mitotically inactive cells known as the quiescent center. We have shown that quiescent center formation precedes the organization of a root meristem and have hypothesized that a quiescent center is necessary for meristem organization. Based on characteristics of cells comprising the quiescent center we believe that these cells are true “stem cells” in the animal sense.

Much of our current work is directed at understanding the underlying molecular and physiological controls of this “stemness”. Pictured below are root apical meristems of (a) Arabidopsis thaliana and (b,c) Zea mays showing the location of various cell populations. For b and c, note the convergence of cell files to a small number of cells, circumscribed in blue-green (the originally designated promeristem). QC, quiescent center; PM, proximal meristem; RC, root cap; RCI, root cap initials; RCJ, root cap junction.

Scale bar = 100 m. It is now widely agreed that the local accumulation of auxin at the embryo pole is THE formative event in the establishment of a quiescent center (a stem cell niche), around which the root meristem organizes. Linking auxin accumulation and meristem establishment is currently a major focus in the lab.

We believe that an important intermediate step in meristem establishment is an auxin-induced change in redox status in the presumptive quiescent center. In order to monitor hypothesized auxin-induced changes in redox status we have developed a GFP which when irradiated with two different wavelengths of light provides a ratiometric measurement of redox status in specific regions/cells in the root (Plant Physiology 141: 397-403). Using this new tool we have shown that the quiescent center maintains a relatively oxidizing (redox) microenvironment and that this is accompanied by low levels in the quiescent center of the two major redox regulators in organisms, gluthathione and ascorbic acid. By altering the redox status, making it relatively more reducing, we are able to stimulate cells in the quiescent center to divide and to lose their stem cell characteristics. In addition to exploring the role of redox status in root meristem development and physiology we are using various GFP marker lines specific to the quiescent center, as well as microarrays, to examine molecular events underlying quiescent center (and root meristem) formation. Current efforts are focusing not only on the quiescent center but also on a zone of meristem cells, the 'transition zone', in which cells lose their meristematic properties, stop dividing, and begin to elongate and differentiate. Towards an understanding of the dynamics of the transition zone, we are currently focusing on a family of transcription factors, the GATA family, members of which have specific expression patterns in the transition zone.