Conjoint Professor Christina Offler

Tina Offler is a plant cell developmental biologist with expertise in cell imaging and localization of genes and their products at cellular and sub-cellular levels. After completing her PhD at the University of Adelaide in 1971, Tina was appointed as a Tutor in the Department of Biological Sciences, University of Newcastle. Tina is a foundation member of the Centre for Plant Science, Discipline of Biological Sciences (ERA 5 - 2010, 2012, 2015); a score indicative of research performance well above world standard. Her research has focused on the regulation of resource transport and allocation in plants and, in particular, developmental mechanisms and their regulation leading to formation of specialized cells called transfer cells. Transfer cells have a primitive origin being found in all plant taxa. They are characterized by intricately-invaginated wall labyrinths supporting an amplified cell membrane surface area enriched in transporters that facilitate high fluxes of nutrients (amino acids, sugars, minerals) at ‘bottlenecks’ within the plant’s transport system; they are the plant’s solution to ‘nutrient traffick jams’. With her colleagues, and supported by Australian Research Council funding for 30 years, she has made, and continues to make, significant contributions to understanding how and when these fascinating cells differentiate and their impact on enhancing plant growth and crop yield. Consistent with her expertise in cell imaging, Tina was joint Academic Head of the University Electron Microscope/X-Ray UnitandChair of the Advisory Committee and User's Forum (1991 - 2002). She was Assistant Dean for Teaching and Learning and Head of School of Environmental and Life Sciences, Faculty of Science & IT; a strong advocate and mentor for academic women in science and her story is included in the University of Newcastle’s 100 Women publication. Tina retired in July 2007 and as a Conjoint Professor continues her research activities. Between 2011 – 2014 she accepted the role of Academic Champion for the Faculty of Science & IT working with academic staff to enhance teaching and learning outcomes for undergraduate students; she is Honorary Director/Chair of the Management Committee, The Don McNair Herbarium, University of Newcastle and was Editor of Phytogen, the Australian Society of Plant Scientists newsletter (2009 – 2013). Tina became a Life Member of the Australian Society of Plant Scientists in 2015.

Research Expertise:

My research is focused on regulation of resource transport and allocation in plants. I have been a co-leader of this research effort with John Patrick since 1983. By integrating structural and physiological studies, we pinpointed the cellular location of regulatory transport processes using developing seeds and fruits as model systems. This approach then allowed directed immunocytochemical studies; molecular analyses, resulting in cloning of key regulatory genes and novel sucrose transporters. It also led to identifying specialized transfer cells that are located at the maternal/filial interface in some seeds. These discoveries instigated a research focus aimed at understanding developmental mechanisms and their regulation leading to formation of transfer cells; a project that is ongoing. 

I developed a transfer cell induction system using Vicia faba(Faba bean) cotyledons. This experimentally-powerful system combined with visualization technologies using SEM/FESEM, TEM and confocal microscopy has, and continues to, underpin our transfer cell research. In collaboration with David McCurdy (1999 - 2011), we made significant contributions to current knowledge of transfer cell wall labyrinths that are comprised of a uniform wall layer from which wall ingrowth papillae arise at loci and project into the cytosol. This structural unit is repeated to build a multi-layered fenestrated network that characterizes a reticulate wall labyrinth architecture, the most common and functionally-effective wall labyrinth design that acts as a supporting scaffold for the plasma membrane. We have established the pattern of assembly and composition of the wall labyrinth and the timing (hours) for V. fabacotyledon epidermal cells to trans-differentiation to a transfer cell morphology and function.  

A method for obtaining peels of trans-differentiated epidermal cells was perfected in our laboratory in 2007. This allowed cell-specific global gene expression to identify genes exhibiting changed expression exclusively in cells induced to trans-differentiate to a transfer cell morphology. These analyses have provided a wealth of data to guide future research directions. Concurrently, we use a targeted approach to identify inductive signals and  now have strong evidence that the trans-differentiation process culminating in a transfer cell morphology in epidermal cells of V. fabacotyledons is initiated by auxin; that polarity and uniform wall layer building is regulated by ethylene and extracellular reactive oxygen species (hydrogen peroxide) and that wall ingrowth papillae construction depends upon activation of groups of membrane-bound calcium channels interspersed with Ca²⁺-ATPases to generate cytosolic Ca²⁺plumes defining the position of their loci. Currently, our focus is the mechanisms and their regulation responsible for wall labyrinth construction. Changes in polysaccharide components and their deposition pattern as well as expression of cellulose synthase (CesA) genes accompanies wall labyrinth formation. The process is largely cytoskeletal independent although the actin network does contribute to regulating wall ingrowth papillae formation. However, many questions remain for example: What is the role of sterol-enriched plasma membrane domains? How is the ROS signal generated? And there are many more!!

Teaching Expertise:

Undergraduate Teaching:
Since becoming a Conjoint Professor in 2007, somewhat regrettably, I have reduced my undergraduate teaching across several years to a point where I no longer participate in the delivery of the undergraduate programme. However, in my four years as Academic Champion for the Faculty of Science & IT I had an opportunity to share my teaching experience with academics from disciplines ranging across communication, design, natural history illustration and IT through psychology to mathematics, physics, chemistry and the earth, environmental and biological sciences. 

My principal goals in undergraduate teaching were to awaken students to the excitement of discovery and to train them in skills required to pursue this process. Such skills are a capacity to question, to develop a logical argument, to plan and undertake experiments, to critically analyse information, to integrate ideas, to think laterally and to communicate in both verbal and written forms. A further goal was to establish for them the importance of organizational skills, responsibility, cooperation, sharing and a positive approach. My teaching philosophy was based on the premise that imparting the conceptual framework of the topic is of paramount importance. This framework then provides a means of ordering the ever-increasing body of information that students need to assimilate to be adequately prepared for the demands of their potential employers or their ongoing education. The integrative nature of processes governing plant growth and productivity was a key platform of my teaching. As a teacher, my goal was to encourage, support and assist students to learn, to discover their own strengths and weaknesses and to develop confidence in their own ability. I operated from a base of respecting students as individuals and working towards avoiding discouraging or intimidating them. 

During my teaching career I taught Plant Science offered for the Bachelor of Science, Bachelor of Environmental Science and Management and Bachelor of Biotechnology at the 3 levels of undergraduate degrees. 

Research Training:
During my career I have been actively involved in research training. I have supervised or co-supervised 19 PhD (4 on mined-land rehabilitation), 3 Master of Science and 18 Bachelor of Science or Bachelor of Biotechnology Honours students to completion as well as co-supervised 4 post-doctoral research associates. Currently (2018), I am co-supervising 3 PhD students. 

Administrative Statement:
During the early years of my career my administrative service was in teaching and learning, women in science, student mentoring and academic selection, the latter as the female representative on committees for several Faculties. My expertise in cell imaging led to leadership roles in the University’s Electron Microscope/X-Ray Unit. As a senior academic, I was appointed to Faculty roles as Assistant Dean Teaching and Learning and Head of School of Environmental and Life Sciences. These roles involving fiscal and personnel management honed my leadership skills being both challenging and rewarding. In retirement, as Academic Champion for the Faculty of Science & IT this experience was broadened through interaction with academic staff from a wide range of disciplines and I continue to mentor colleagues and students.