Discipline: Biological Sciences
Subcategory: Plant Research
Francisco Fernandez - California State University San Marcos
Co-Author(s): Kassandra Sanchez, California State University San Marcos, CA; Miguel Rosas, California State University, San Marcos, CA
Glutaredoxins are small redox enzymes that use glutathione as a substrate to reduce disulfide bonds in target proteins. Plants have a far greater number of glutaredoxins than other organisms, mostly due to a unique clade of class III glutaredoxins that are exclusively found in higher plants. Previous studies in our lab demonstrated that a small group of class III glutaredoxin genes are strongly upregulated by nitrate in Arabidopsis thaliana, and that reducing expression of these nitrate-regulated glutaredoxins leads to increased primary root growth. Thus, glutaredoxins appear to link nutrient sensing with plant growth and root system architecture. To further explore this hypothesis, we have generated two groups of transgenic plants that 1) constitutively overexpress several nitrate-induced glutaredoxins and 2) completely inactivate targeted glutaredoxins via CRISPR-Cas9 technology. The coding sequence of the AtGRXS5, AtGRXS6, and AtGRXS8 genes have been sub-cloned into an expression cassette and used to transform A. thaliana. Preliminary results suggest that high-level constitutive overexpression of these genes causes a severe dwarf phenotype in transgenic plant lines, again implicating the nitrate-regulated glutaredoxins as important regulators of plant growth. Work with CRISPR-Cas9 knockout lines is at an earlier stage, but CRISPR vectors targeting AtGRXS6 and the AgGRXS3/4/5/7/8 gene cluster have been constructed and utilized for plant transformation. We are currently screening these transgenic plant lines to identify knockouts in the target gene(s). Because the nitrate-regulated glutaredoxins appear to be important regulators of primary root growth, this work could have significant broader implications related to important agricultural traits such as root depth (drought tolerance) and nitrogen use efficiency.
References: Meyer Y, Buchanan BB, Vignols F, Reichheld JP (2009) Thioredoxins and glutaredoxins: unifying elements in redox biology. Annu Rev Genet 43: 335-367.
Patterson K, Walters LA, Cooper AM, Olvera JG, Rosas MA, Rasmusson AG, Escobar MA (2016) NitrateRegulated Glutaredoxins Control Arabidopsis Primary Root Growth. Plant Physiol 170: 989-999Not Submitted
Funder Acknowledgement(s): This work was supported by NSF RUI grant 1651584 awarded to Matthew Escobar PhD, professor of biological sciences, California State University San Marcos, San Diego, CA 92027
Faculty Advisor: Matthew Escobar, firstname.lastname@example.org
Role: Participated in sub-cloning of the Cas9 vectors for Arabidopsis thaliana and preliminary phenotype screening for overexpression lines. I am in the process of screening for Cas9 mutant plants.