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United States Department of Agriculture

Agricultural Research Service

Research Project: CHARACTERIZATION AND ENHANCEMENT OF PLANT RESISTANCE TO WATER-DEFICIT AND THERMAL STRESSES

Location: Plant Stress and Germplasm Development Research

2008 Annual Report


1a.Objectives (from AD-416)
1)Identify and functionally characterize genes central to the adaptation of plant to water-deficit and thermal stresses. 2)Discover and/or develop germplasm enhanced for stress resistance traits. 3)Identify and characterize water-deficit and thermal stress-responding promoters for use in controlled expression of stress resistance genes and for testing of a user-friendly plant stress reporter system for crop management.


1b.Approach (from AD-416)
A multidisciplinary research approach will be utilized because of the complexity of the problems to be addressed. Genes will be identified via expression databases and mutational analyses. Physiological and molecular characterizations will be used to identify germplasm with enhanced stress tolerances. Transformational technologies will be used in the development of plants with enhanced stress tolerances and plants with stress responsive reporter genes.


3.Progress Report
All milestones were either fully or substantially met during this reporting period. The research showed that a low-cost IRT sensor in a wireless instrument package could be used in irrigation scheduling. The BIOTIC device for irrigation scheduling was shown to provide a relatively straightforward means to establish and manage water deficits. Differences in root development as a result of the alternate furrow SDI configuration (dry furrow showed higher root occupancy than wet furrow) were identified. The impact of storage environments on cotton seedling vigor was identified. Genetic diversity in the magnitude of hydraulic lift, or the ability of the plant to transfer water from wet zones in the soil profile to drier zones through the root system was identified. Synthetic promoters controlling gene expression were produced, tested, and released to researchers and stakeholders. The physiological reason for heat sensitivity in some corn lines was identified. A method to select transgenic plants without the use of antibiotic resistance was developed. (NP302, Component 2)


4.Accomplishments
1. A low cost infrared thermometry system: Scientists within the Plant Stress and Germplasm Development Unit in Lubbock, Texas, deployed a newly designed low-cost infrared thermometry system in field experiments in Narrabri NSW, Australia, and Lubbock, Texas. Results demonstrate the utility of a low-cost IRT sensor in a wireless instrument package. This system simplifies plant temperature measurements in both research and agricultural production settings. (NP302, Component 2)

2. Management of water deficits in research and agricultural production settings: Scientists within the Plant Stress and Germplasm Development Unit in Lubbock, Texas, evaluated the utility of the BIOTIC irrigation protocol for the establishment and maintenance of specific water deficits in plants. BIOTIC systems were deployed in field plots of cotton under various irrigation levels in order to compare the patterns of canopy temperature resulting from differential water status in the plants. Findings indicate that the device could provide a relatively straightforward means to establish and manage water deficits in research plots. (NP302, Component 2)

3. Subsurface drip irrigation impacts root development: Scientists within the Plant Stress and Germplam Development Unit in Lubbock, Texas, evaluated a series of cotton varieties for root system development in field studies in response to different water applications using sub-surface drip irrigation (SDI). The results indicated that there were differences in root development as a result of the alternate furrow SDI configuration (dry furrow showed higher root occupancy than wet furrow). There were no differences in root development between the varieties. (NP302, Component 2)

4. Cotton seed storage impacts seed quality: Scientists within the Plant Stress and Germplasm Development Unit in Lubbock, Texas, evaluated the impact of storage environments on cotton seedling vigor. The study showed that storage temperature was the primary factor leading to differences in maintaining seedling vigor rather than differences in relative humidity over the two-year storage period. Variety differences in seedling vigor, regardless of location, were also noted. (NP302, Component 2)

5. Water movement through roots to dry soil: Scientists within the Plant Stress and Germplasm Development Unit in Lubbock, Texas, evaluated genetic diversity in the magnitude of hydraulic lift, or the ability of the plant to transfer water from wet zones in the soil profile to drier zones through the root system. Genetic differences in root responses were identified. These findings could lead to the development of germplasm for maintaining viable roots in zones that typically experience soil drying and root death. (NP302, Component 2)

6. Synthetic plant-functional promoters: Scientists within the Plant Stress and Germplam Development Unit in Lubbock, Texas, produced, tested, and released synthetic promoters to researchers and stakeholders. A detailed quantitative analysis of the function and interaction of individual transcriptional promoter elements was also performed to better understand how different regulatory sequence elements interact to control gene expression. This work adds to a limited collection of well-characterized plant promoters that are in the public domain, and provides novel insight that contributes to an improved ability to construct and employ gene regulatory systems for plant genetic engineering. (NP302, Component 1B)

7. Gene silencing and transgene function in plants: The impact of gene silencing on transgene (and native gene) activity in plants (co-suppression) was one of the first examples of a set of molecular processes that use small RNA (smRNA) to effect gene expression in eukaryotes. In order to effectively express and regulate transgenes that have the potential of improving plant stress resistance, it is necessary to better understand exactly how gene silencing in plants functions. Scientists within the Plant Stress and Germplam Development Unit in Lubbock, Texas, have developed several model systems for examining post-transcriptional gene silencing in plants and have begun the process of quantifying and characterizing transgene silencing in plants. smRNA gene regulation has been implicated as a player in plant stress response and a better understanding of the molecular processes involved is essential to contending with, and potentially employing, smRNA systems plants engineered for improved stress tolerance. (NP302, Component 3)

8. Visible stress reporter system: Producers must contend with a constantly changing environment that can dramatically impact the viability and yield of crops. It is standard practice to attenuate environmental stresses through adaptive agronomic practices, such as enhanced application of water and fertilizer. Scientists within the Plant Stress and Germplam Development Unit in Lubbock, Texas, explored the possibility of developing a genetic system that would provide the producer with simple visible cues (e.g., plant pigment production) as to the status of crops in the field, allowing for a more efficient agronomic response. By choosing the appropriately regulated plant promoter (e.g., water or heat stress responsive) and pigment-inducing plant gene (e.g., transcription factor for anthocyanin production), it is potentially possible to engineer plants that will alter their pigmentation in response to specific stresses, alerting the producer that action is required. Any system that makes the process of agronomic adaptation easier and more efficient would contribute to both increased crop yield and enhanced conservation. (NP302, Component 3)

9. Corn heat sensitivity identified: Scientists within the Plant Stress and Germplam Development Unit in Lubbock, Texas, showed a correlation between the amounts of phosphatidic acid (PA) and heat tolerance in corn. The findings were verified in two maize inbred lines by lipid profiling. The likely role of PA in heat tolerance in maize was further suggested by the significant induction of PA in leaf tissues of maize plants upon high temperature treatments. Several recombinant inbred lines (RILs) of distinctive heat tolerance were identified from the cross of these two inbred lines. The role of PA in heat tolerance will be further examined by lipid metabolic analysis of these RILs. (NP302, Component 1)

10. Antibiotic resistance no longer needed to select transgenic plants: Scientists within the Plant Stress and Germplam Development Unit in Lubbock, Texas, developed a method to select transgenic plants without the use of antibiotic resistance. A gene involved in heat tolerance was used as a selection tool, allowing transformed cells, embryos, and plants to survive a high temperature challenge, while non-transformed tissues did not survive the heat challenge. This technology eliminates the need to use antibiotic resistance genes in selection genetically modified plants. (NP 302, component 3)


6.Technology Transfer

Number of Active CRADAs1
Number of the New MTAs (providing only)2
Number of Invention Disclosures Submitted1
Number of Non-Peer Reviewed Presentations and Proceedings4

Review Publications
Mahan, J.R., Gitz, D.C. 2007. A dynamic model of cotton emergence based on the thermal dependence of malate synthase. Agronomy Journal. 99(6):668-674.

Burke, J.J., O'Mahony, P., Oliver, M.J., Velten, J.P. 2008. A selection procedure for identifying transgenic cells and embryos of cotton without the use of antibiotics. In Vitro Cellular & Development Biology. 44(4):246-253.

Kottapalli, K., Payton, P., Rakwal, R., Agrawal, G., Shibato, J., Burow, M., Puppala, N. 2008. Proteomics analysis in mature seed of four peanut cultivars using two-dimensional gel electrophoresis reveals distinct differential expression of storage, anti-nutritive, and allergenic proteins. Plant Science. 175(3):321-329.

Last Modified: 7/28/2014
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