- Professor
- Department of Crop, Soil, and Environmental Sciences (CSES)
- University Of Arkansas System, Division of Agriculture
- 115 Plant Sciences Building, Fayetteville, Arkansas 72701
- Phone: 479-575-4872
- Fax: (479) 575-7465
- Email: vibhas@uark.edu
- Webpages:
- https://crop-soil-environmental-sciences.uark.edu/vibha-S-lab/index.php
- https://crop-soil-environmental-sciences.uark.edu/people/faculty-directory/uid/vibhas/name/Vibha+Srivastava/
- Research Interests:
- > Site-specific gene integration, targeted mutagenesis, gene stacking and functional genomics
- > Gene editing & investigating the role of CRISPR/Cas9 mediated genetic modifications for plant improvement
- > Epigenetic mechanisms associated with gene regulation
Dr. Vibha Srivastavais a Professor in the department of Crop, Soil, and Environmental Sciences at the University of Arkansas, Fayetteville where she teaches and conducts research that focuses on plant biotechnology, molecular genetics and molecular biology areas. The Srivastava laboratory is developing methods for expressing traits or validating gene functions using rice as the model species. Our transformation methods are based on site-specific integration of single or multigene stacks in addition to the standard transformation approaches.
To knockout genes, we use CRISPR/Cas9 based methods that utilize strong constitutive or inducible targeting approaches.Using these methods, we have developed CRISPR knockout lines for different rice genes.
Using recombination systems such as Cre-lox and FLP-FRT, we developed methods for marker excisions and marker-free site-specific integration. Overall, our goal is to develop transformation methods and other approaches for understanding gene function in rice.
Research Participants
(Program Associate)
(Program Associate)
(Program Associate)
(Graduate Student)
Role in the project & Research outcomes
Srivastava Lab is involved in the project for validation of candidate genes identified by genome wide association studies (GWAS) for grain yield and quality under HNT stress by transformation into US rice cultivars, and genome editing using established methods.
1. Role of Chalk5 in grain chalkiness
Srivastava lab identified a few candidate genes from the literature for investigating their roles in grain chalkiness through transgenic/CRISPR approach. One of these genes is Chalk5 encoding a vacuolar H+-translocating pyrophosphatase that controls endomembrane trafficking in the endosperm. Enhanced activity of Chalk5 presumably leads to disturbed endomembrane trafficking and increased grain chalkiness (Li et al., 2014). However, this hypothesis has not been tested by genetic approaches. Towards this, Srivastava et al, developed CRISPR-targeted lines of rice that contained mutations in the Chalk5 promoter elements.
The resulting lines were analyzed by gene expression and grain morphology analysis (scanning electron microscopy) that revealed: (i) Chalk5 is highly expressed at 10 days after flowering (DAF), when efficient grain filling is important for the formation of non-chalky grains, (ii) CRISPR-targeting of the two promoter elements (simultaneous) led to the suppression of Chalk5 gene (Fig. XX), (iii) Chalk5-CRISPR lines showed more compact granule morphology compared to the non-targeted WT controls. In summary, Chalk5 appears to control starch granule morphology of rice even under ambient conditions.
2. Starch granule morphology correlates with grain chalkiness
The pattern of starch granules (small and round vs large and edged) determines %chalk in rice grains (Fig. X). This genotype-dependent pattern correlates with the expression pattern of starch synthesis genes, ADP-Glucose Phosphorylase, Starch Synthase IIA, and Granule Bound Starch Synthase I. Break in the temporal coordination in these genes under HNT conditions leads to round granules that generate high %chalk (Gann et al. (2021) Plant-Environ Interac. 2(4): 165-176; https://doi.org/10.1002/pei3.10054
3. Expression patterns of starch biosynthesis genes
These genes provide clues on grain chalkiness in rice cultivars. Coordinated expression of AGPase subunit genes, AGPL1, AGPL2, AGPL4, and starch synthase genes, GBSSI and SSIIA through early reproductive phases leads to the formation of large polyhedral granules packed tightly in the grains.
