Plant diseases have a devastating impact on agricultural production and food supply every year. Plant viruses are a major threat to the cultivation of many agricultural crops, causing serious economic losses worldwide. For many years, these pathogens have been controlled by conventional plant protection methods such as crop rotation, destruction of infected sources breeding for resistance, and chemical control of relevant insect vectors. This project will involve study of interaction between Arabidopsis thaliana and Turnip Crinkle Virus (TCV), with an aim to elucidate mechanisms governing resistance of plants to viral infections. The overall goal of this research will be to dissect the molecular and biochemical basis of signaling required for hypersensitive response and resistance to TCV. This will include determining the genetic basis of resistance to TCV by cloning and characterization of a putative suppressor of resistance to TCV. In addition, several TCV coat protein recognition defective mutants will be characterized further and molecular and biochemical basis of SA-mediated regulation of resistance gene expression will be studied. This work will provide novel and important insights into the complex defense signaling networks that facilitate communication between host and pathogen. By elucidating the mechanism(s) through which plants perceive and resist viral infection, successful strategies for engineering and/or manipulating disease resistance may be developed. Other broader impacts of this study include training of high school, undergraduate, graduate and postdoctoral students. One important aim of this work will be to foster a community of undergraduate students, particularly those from traditionally underrepresented groups, by including them as members of the scientific team. In addition, attempts will be made to integrate research with the extension services available at the University of Kentucky to enhance awareness of the recent advances in crop resistance among farmers and agribusiness representatives.
Plant diseases are a significant problem for agriculture worldwide, with currently up to 30% of potential crop yield being lost to pests and pathogens. Plant diseases also are a major barrier to food sustainability in the developing world and food security worldwide. We have used the highly tractable Arabidopsis-Turnip Crinkle Virus (TCV) pathosystem to gain new insight into how plants protect themselves against disease-causing pathogens. These studies have resulted in the identification and partial characterization of two new components of the plant immune system, CRT1 and CRT2, and the importance of light in disease resistance. Using a genetic approach, two mutants that are compromised for recognition of TCV, crt1 and crt2, were identified. Both are compromised for basal resistance to virulent pathogens and for the strongest level of immunity that is conferred by resistance genes, termed R gene-mediated resistance. CRT1 has been cloned and thus identified. CRT1 interacts with a wide variety of R proteins, which mediate resistance to a broad spectrum of pathogens, suggesting that it plays a fundamental role in immunity. Although CRT2 has not yet been cloned, genetic analyses suggest that it also functions at multiple levels of immunity. HRT is the R protein conferring resistance to TCV in Arabidopsis. Our previous studies have shown that the level/amount of HRT in the plant influences the level of resistance to TCV, with higher levels conferring greater resistance. Our recent analyses indicate that the presence of light immediately after TCV infection is required for the stability of HRT and hence TCV resistance. Using a genetic approach the photoreceptors cyrptochrome 2 and phototropin 2 have been shown to be required for HRT stability and for HRT-mediated resistance. In summary, this NSF-funded project has identified three new components that play important roles in plant immunity. The results of this basic research are providing a fundamental understanding of plant immunity which is essential to improving plant health and hence food security. This is increasingly important in light of three critical factors: i) continued population growth with ever increasing demand for high-protein diets by the large increase of middle-class population in developing countries such as China and India, ii) dramatic rise in use of crop plants for production of biofuels for energy, and iii) global climate change that will result in a decrease in the amount of arable land and an increase in stress to plants such as drought and high temperatures. This project has also supported the training of present and future scientists including five postdoctoral fellows, one graduate student, and six undergraduate students.
