Paul Nakata Lab

Nakata Lab Research Projects

Master
Content

Factors regulating plant nutritional quality and productivity

The increasing frequency of abiotic stress, commonly associated with climate change, negatively impacts the nutritional quality and productivity of crop plants (e.g., legumes), and thus, has become a major threat to global food security.  In response to this threat plant scientists have been trying to establish legumes that maintain good productivity under conditions of abiotic stress.  To date, plants engineered with abiotic tolerance, in general, also exhibit penalties in yield and often are compromised in other aspect of growth and development.  Thus, the development of new strategies that minimize these penalties are required. In addition to yields, the impact of these genetic modifications on nutrient concentrations, before and after exposure to abiotic stress, should also be considered.  Likewise, effort to engineer nutritionally improved plants need to consider issues of reduced plant productivity and other pleotropic effects under abiotic stress environments.  In this study, gene targets with the potential to confer abiotic tolerance (with lower penalties) as well as gene targets with the potential to confer an enhancement in nutritional quality (with lower penalties) will be selected and genetically modified in the model legume, Medicago truncatula.  Plants containing the selected gene modification then will be assessed for changes in nutritional quality and productivity under abiotic stress and non-stress conditions.  Plant lines displaying abiotic tolerant traits then will be crossed to the engineered plants containing nutritional improvements to generated plant lines containing both desired traits.  Plant lines containing these stacked traits will also be evaluated for changes in nutritional quality and productivity under stress and non-stress conditions. Investigation into the mechanisms conferring the abiotic and nutritional improvement will also be initiated using molecular-genetic methodologies.  This information is necessary for the design of rational translational strategies to help meet our future global food and nutritional needs.

Supported by USDA

Structural and mechanistic studies of oxalate catabolism

Oxalic acid is biosynthesized by different organisms to gain a selective advantage to enhance their survival. Considering the widespread occurrence of oxalate in nature and its broad impact on a host of organisms, it is surprising that so little is known about the turnover of this important acid. Recently, we discovered a CoA-dependent pathway of oxalate catabolism and found that it is present in both plants and microbes, underscoring the broad importance of this pathway. As a step towards elucidating this CoA-dependent pathway of oxalate catabolism, we propose to conduct structural and functional studies to gain a better understanding of the biological role and mechanism of key enzymes in oxalate turnover. Such studies will provide a starting point for the rational manipulation of the substrate and product specificities of these key enzymes and facilitate metabolic engineering of plants directed toward improving the nutritional quality and production of plant derived foods.

Supported by NSF

Deciphering the mechanism of calcium oxalate crystal formation and function

The biologically controlled formation of mineral deposits is often referred to as biomineralization. Biomineralization is widespread in nature occurring in a range of organisms from the simple microbe to complex humans. Understanding the process of how living organisms biosynthesize these intricate and biomolecular materials could have a beneficial impact on nutrition, agriculture, medicine, engineering, climate science, and material science.  Although calcium oxalate crystal formation is the most common biomineralization process in plants, very little is known about how and why these crystals form. The diversity of crystal morphologies, as well as their prevalence and spatial distribution have led to a number of hypotheses regarding the biological function of crystal formation in plants. Proposed functions include roles in ion balance, in plant defense, in tissue support, in detoxification, and in light gathering and reflection.  Definitive proof validating many of these hypotheses are still lacking. As a step toward determining how and why plants form crystals of calcium oxalate, we established an integrated molecular-genetic approach to deconstruct this process in the legume model, Medicago truncatula and reconstruct this process in Arabidopsis.