Genetically Engineered Potato Plants Which Do Not Produce O3-induced Ethylene A Mechanism of O3 Tolerance?

EPA Grant Number: R823193
Title: Genetically Engineered Potato Plants Which Do Not Produce O3-induced Ethylene A Mechanism of O3 Tolerance?
Investigators: Pell, Eva J. , Arteca, Richard N.
Institution: Pennsylvania State University
EPA Project Officer: Manty, Dale
Project Period: October 1, 1995 through September 30, 1998
Project Amount: $412,615
RFA: Exploratory Research - Environmental Biology (1995) RFA Text |  Recipients Lists
Research Category: Biology/Life Sciences , Health , Ecosystems


When plants are exposed to ozone (O3), foliage frequently responds by emitting ethylene. A number of researchers have suggested that O3-induced ethylene is responsible for many subsequent effects of this pollutant. This hypothesis has been tested by using inhibitors of ethylene biosynthesis and demonstrating that other O3 responses were repressed as well. The inhibitors used in all of these studies were pyridoxal phosphate inhibitors, which are largely nonspecific. As such, while the results of the inhibitor studies were consistent with the notion of ethylene as a potential regulator of the O3 response, they could not provide a reliable test of the hypothesis.

The enzyme 1-aminocyclopropane-1-carboxylic acid (ACC) synthase regulates ethylene biosynthesis. In this laboratory, a gene has been isolated for O3-induced foliar ACC synthase (ST-ACS4) in potato foliage. The objectives of this research project are to produce transformed potato plants which carry antisense for ST-ACS4, and then to test whether plants which are incapable of producing this specific O3-induced ACC synthase will be less sensitive to the pollutant. In order to transform the plants it will be necessary to synthesize a construct for the ACC synthase gene which has the antisense orientation of the cDNA for the ST-ACS4 gene. This insert will be used to transform Agrobacterium tumefaciens cells. A potato regeneration system will be developed for Solanum tuberosum cv. Norchip. During the preculture phase of potato regeneration, stem internode sections will be soaked in Agrobacterium cell suspensions to allow infection with the antisense insert for the ST-ACS4 gene. The insert will carry with it a gene to confer resistance to the antibiotic kanamycin. The potato explants will be cultured on kanamycin and only those sections carrying the insert for the ST-ACS4 antisense will grow. When successful transformants carrying the antisense for the ST-ACS4 gene have been identified, plants will be characterized in order to identify a line(s) which will completely inhibit O3-induced ethylene production. These transformants will then be propagated in order to multiply the tubers yielding a large number of clonally propagated individuals for experimentation.

These experiments will provide critical tests to determine the potential for ethylene to act as an early signal in the O3 response, and as a regulator of subsequent effects. These transformants may also provide germplasm which could be useful in development of less O3 sensitive potato plants.

Supplemental Keywords:

Health, Scientific Discipline, Environmental Chemistry, Genetics, Chemistry, Risk Assessments, Engineering, Biology, ozone, ethylene, genetic engineering, potato plant, pyridoxal phosphate inhibitor, biosynthesis, agrobacterium cell supression

Progress and Final Reports:

1999 Progress Report
Final Report