C. B. Rajashekar
Plant Environmental Stress
Division of Horticulture
crajashe@oznet.ksu.edu
Research Profile
Environmental stresses can not only have a serious impact on the productivity of crops but also play a key role in determining their adaptability, even their survival in a given region. Because of a great deal of similarity in plants responses to different environmental stresses, we are currently examining the commonality and interrelationships among stress responses to a number of stresses and their underlying mechanisms. However, our primary area of research focus is to understand plant's tolerance to low temperatures which is a major concern in temperate and subtropical regions. Various aspects of freezing tolerance in plants are being investigated, including, molecular responses to cold, genetic manipulations and other strategies to improve and understand the freezing tolerance in plants. Using Arabidopsis, we are currently looking at molecular responses to cold and water stress, both of which plants are exposed to during cold acclimation. We have characterized the cold-responsive transcription activators and genes to elucidate the similarities in signaling pathways. In addition to the well-studied cold-responsive genes, we are exploring the role of ADH (alcohol dehydrogenase) and PDC (pyruvate decarboxylase ) genes in response to cold. These genes, typically activated in plants during hypoxia, are expressed during cold acclimation as well, but very little is known about their involvement in freezing tolerance. We are characterizing the possible role of cold-responsive transcription activators in activation of ADH and PDC. ADH activity leads to ethanol accumulation in plants which can have a definite impact on membrane fluidity and thus, on the stress tolerance of plants. We are also initiating studies to compare the molecular responses associated with hypoxia and cold stress.
Our research efforts also include metabolic engineering of phospholipid-catabolyzing enzyme in Arabidopsis to study its possible role in freezing tolerance. Phospholipase D is a catabolic enzyme which breaks down phospholipids in plants and is known to be activated in response to various stresses. We have characterized the role of this enzyme in freezing tolerance of Arabidopsis by using antisense suppression of phospholipase D gene. We are also exploring the use of PLD inhibitors in Arabidopsis and strawberry to block the enzyme activity and lower the levels of phosphatidic acid, one of the products of phospholipid break down and a destabilizer of membrane bilayers, and to determine their effectiveness in inducing freezing tolerance.
Research Group:
Graduate Students:
Yuwen Zhang--Ph. D student
Manasa Panda- M. S. student
Visiting Scientist:
Dr. Nam-Jun Kang
