http://nova.newcastle.edu.au/vital/access/services/Feed ${session.getAttribute("locale")} 5 http://nova.newcastle.edu.au/vital/access/manager/Repository/uon:4250 Research Doctorate - Doctor of Philosophy (PhD) 2011-12-07T22:40:09.710Z ]]> http://nova.newcastle.edu.au/vital/access/manager/Repository/uon:8254 SOMATIC EMBRYOGENESIS RECEPTOR-LIKE KINASE (SERK) genes have been demonstrated to play a role in somatic embryogenesis in several plant species. As more is learnt about these genes, the view of their role in plant development has broadened. The Medicago truncatula MtSERK1 gene has been associated with somatic embryogenesis and in vitro root formation. In order to study the role of MtSERK1 in development further, the MtSERK1 promoter sequence has been isolated and cloned into a promoter–GUS analysis vector. SERK1 promoter-driven GUS expression was studied in A. tumefaciens-transformed cultures and regenerated plants, in A. rhizogenes-transformed root clones, and in nodulation. In embryogenic cultures, GUS staining is detected after 2 d of culture at the edge of the explant and around vascular tissue. Expression at the explant edge intensifies over subsequent days and then is lost from the edge as callus formation moves inward. MtSERK1 expression appears to be associated with new callus formation. When somatic embryos form, GUS staining occurs throughout embryo development. Zygotic embryos show expression until the heart stage. The in planta studies reveal a number of interesting expression patterns. There appear to be three types. (i) Expression associated with the primary meristems of the root and shoot and the newly formed meristems of the lateral roots and nodule. (ii) Expression at the junction between one type of tissue or organ and another. (iii) Expression associated with the vascular tissue procambial cells. The data led us to conclude that MtSERK1 expression is associated with developmental change, possibly reflecting cellular reprogramming. 2011-07-14T02:40:25.854Z ]]> http://nova.newcastle.edu.au/vital/access/manager/Repository/uon:2404 Using a combination of two-dimensional gel electrophoresis (2-DE) protein mapping and mass spectrometry (MS) analysis, we have established proteome reference maps of Medicago truncatula embryogenic tissue culture cells. The cultures were generated from single protoplasts, which provided a relatively homogenous cell population. We used these to analyze protein expression at the globular stages of somatic embryogenesis, which is the earliest morphogenetic embryonic stage. Over 3000 proteins could reproducibly be resolved over a pI range of 4-11. Three hundred and twelve protein spots were extracted from colloidal Coomassie Blue-stained 2-DE gels and analyzed by matrix-assisted laser desorption/ionization-time of flight MS analysis and tandem MS sequencing. This enabled the identification of 169 protein spots representing 128 unique gene products using a publicly available expressed sequence tag database and the MASCOT search engine. These reference maps will be valuable for the investigation of the molecular events which occur during somatic embryogenesis in M. truncatula. The proteome reference maps and supplementary materials will be available and updated for public access at http://semele.anu.edu.au/. 2010-04-27T06:36:36.659Z ]]> http://nova.newcastle.edu.au/vital/access/manager/Repository/uon:4721 Medicago truncatula Gaertn. cv. Jemalong, a pasture species used in Australian agriculture, was first proposed as a model legume in 1990. Since that time M. truncatula, along with Lotus japonicus (Regal) Larsen, has contributed to major advances in understanding rhizobia Nod factor perception and the signalling pathway involved in nodule formation. Research using M. truncatula as a model has expanded beyond nodulation and the allied mycorrhizal research to investigate interactions with insect pests, plant pathogens and nematodes. In addition to biotic stresses the genetic mechanisms to ameliorate abiotic stresses such as salinity and drought are being investigated. Furthermore, M. truncatula is being used to increase understanding of plant development and cellular differentiation, with nodule differentiation providing a different perspective to organogenesis and meristem biology. This legume plant represents one of the major evolutionary success stories of plant adaptation to its environment, and it is particularly in understanding the capacity to integrate biotic and abiotic plant responses with plant growth and development that M. truncatula has an important role to play. The expanding genomic and genetic toolkit available with M. truncatula provides many opportunities for integrative biological research with a plant which is both a model for functional genomics and important in agricultural sustainability. 2010-04-27T05:02:44.544Z ]]>