Walia Lab

University of Nebraska Lincoln

We study the effect of environmental stress on early endosperm development. Endosperm is the primary source of nutrition for humans. The development of endosperm is highly sensitive to environmental factors such as heat and drought stress and results in reduced seed size. Our goal is to identify the genetic and epigenetic factors that determine this sensitivity so they can be altered to make grain development more resilient in cereals such as rice and wheat.

1. Folsom, J.J., Begcy, K., Xiaojuan, H., Wang, D., Walia H., Rice FIE1 regulates seed size under heat stress by controlling early endosperm development. 2014, Plant Physiology
2. Begcy, K., Walia H., Drought stress delays endosperm development and misregulates genes associated with cytoskeleton organization and grain quality proteins in developing wheat seeds. 2015, Plant Science

Root traits are critical for drought adaptation. We are interested in elucidating the molecular mechanisms for adaptive root responses to water stress in wheat. Recent findings from this project are reported in Placido et al. 2013 in Plant Physiology. This paper describes the physiological consequences of enhanced root biomass under water stress in wheat. We are currently, attempting to identify novel genes and alleles from alien introgression in bread wheat from wild relative in collaboration with other laboratories. Our approach for this project is to use RNAseq to identify novel factors introduced from the wild accession and functionally validate candidate genes in wheat for their role in drought adaptation. The collaborative project is supported by the Daugherty Water for Food Institute at the University of Nebraska.

More than a billion dollars worth of rice yield is lost to flash floods each year in South Asia. The major locus regulating the submergence tolerance in rice has been identified by Xu et al., 2006. The gene conferring submergence tolerance is called Sub1A. We are interested in elucidating the molecular mechanism underlying the Sub1A-mediated submergence tolerance in rice. Improved understanding of the Sub1A action can help identify further target genes for enhancing submergence tolerance in rice and transferring the trait to other cereals such as maize and wheat. Recent collaborative work on the submergence tolerance project is reported in Schmitz et al., 2013. We have identified plant hormone brassinosteroids to be important in Sub1A action during submergence.
1. Schmitz et al., 2013. SUB1A-mediated submergence tolerance response in rice involves differential regulation of the brassinosteroid pathway. New Phytologist.
2. Campbell, et al. Genetic and molecular characterization of submergence response identifies Subtol6 as a major submergence tolerance locus in maize. Plos One

3. Jung et al., 2010. The submergence tolerance regulator Sub1A mediates stress-responsive expression of AP2/ERF transcription factors.

Salinity is an important limitation for rice yields and results in estimated yield losses of 12 billion dollars annually. The goal of this collaborative NSF Plant Genome Research grant is to identify the genetic and physiological basis of salinity tolerance in rice. We are using the automated image-based phenotyping for dissecting the physiological responses for a diverse set of rice germplasm. The phenotypic information will be combined with genotypic data for the rice diversity panel for genome-wide association studies. Bioinformatics and computational biology approaches will provide new molecular insights that can be lead to development of salt-tolerant rice cultivars.

Phenomics and Genomics figure
Manhattan plot for the logistic growth-response association analysis in rice under salinity stress.

1. Walia et al., 2009. Comparing genomic expression patterns across plant species reveals highly diverged transcriptional dynamics in response to salt stress.
2. Walia et al., 2007. Genome-wide transcriptional analysis of salinity stressed japonica and indica rice genotypes during panicle initiation stage.
3. Walia et al., 2005. Comparative transcriptional profiling of two contrasting rice genotypes under salinity stress during the vegetative growth stage.
4. Campbell et al., 2015 Integrating Image-Based Phenomics and Association Analysis to Dissect the Genetic Architecture of Temporal Salinity Responses in Rice.