Genetic manipulation to increase desirable traits in crops is critical to increasing agricultural productivity. These changes have mostly involved modifying the plant’s DNA sequence. However, environmental responses have increasingly been shown to be mediated by epigenetics, which involves heritable changes in phenotype or gene expression without changes in DNA sequence. Specifically, epigenetic changes play a major role in regulating plant responses to drought, an increasing problem for agriculture due to climate change. For example, exposure of plants to abiotic stresses, such as water limitation, triggers epigenetic changes. These differences include remodeling of chromatin, the network of DNA, RNA and various proteins making up chromosomes, and related changes in regulatory mechanisms, including small non-coding RNAs.
Efforts in this project focus on unraveling the role epigenetic signals play in acclimation to and recovery from drought through effects on individual transcription factors or transcriptional networks that direct entire metabolic pathways. Sorghum, the world’s fifth most important cereal crop in terms of production and acreage, is used in the U.S. primarily for animal feed and, more recently, both grain and sweet sorghums are used for biofuel production. Sorghum was chosen for this project due to its notable advantages as a bioenergy feedstock because of its relative drought tolerance, resulting in its reduced environmental footprint compared to its close relative, corn. In the face of climate change, sorghum appears ideal for the increasingly water-challenged areas of the world. Understanding the mechanisms by which sorghum is able to survive drought will allow us to improve the drought tolerance of other important crops, like corn and other cereal grains.
In this project we, with a number of other colleagues, will follow responses to water deprivation in the field of two sorghum cultivars differing in their drought responses. Phenotypic analyses will be conducted in the field to chart growth, flowering, biomass accumulation and other observable characteristics. Leaf and root samples will be taken to perform molecular phenotyping, using epigenetic, transcriptomic, metabolomic and proteomic footprints. As potential molecular mechanisms are identified, targeted engineering will be used to validate suggested findings. One transcription factor of interest identified in barley (Su et al. 2015. Nature 523: 602-608), that impacts positively grain and stem biomass is SUSIBA2, which was shown in rice to funnel carbohydrate from root production of methane to biomass in the stem and grain, resulting in an increase in yield. In a similar approach, Sorghum bicolor immature embryos have been transformed with Agrobacterium tumefaciens, harboring a construct containing both the SUSIBA2 gene, driven by HvSBEIIb, a sugar-inducible barley promoter, and the nptII selectable maker gene. Transgenic plants have been generated and are currently being analyz
ed to see what impact overexpression of this gene has on sorghum grain and stem yield as well as starch biosynthesis. Additional genes will be studied as they are identified.
The duties and goals of the student will depend on their skill level. The student might care for plants in the green house and in the growth chambers, plant seeds, harvest seeds, perform in vitro tissue culture and transformation for gene introduction via engineering and editing approaches, and conduct biochemical and molecular studies on engineered materials. The student may also be involved in preparing materials for the various analyses that will be performed. The student will work directly with a postdoctoral fellow, a research assistant (also once a SPUR student), other undergraduates and the principal investigator. Students will participate in lab meetings and be expected to contribute to presentations and publications, as appropriate.
Enthusiasm for research is necessary; previous laboratory experience outside the classroom is desirable. Care-to-detail and commitment to scheduled work times are critical