Prasanta K. Subudhi, Neil Parami, Alicia Ryan and Stephen A. Harrison    

Disappearance of Louisiana coast at the rate of 30 square miles a year is no trifling matter. Louisiana’s wetland, which provides food and habitat to numerous plants and animals, is one of the most productive ecosystems on Earth. Both natural and human activities have seriously disturbed this ecosystem to such an extent that the native plants are no longer able to adapt to this changing environment.

While the use of native vegetation is well accepted as a cost-effective measure to prevent coastal land loss, the concept of genetically improving wetland plants for the changing marsh environments is quite novel. LSU AgCenter scientists are focusing on development of genetically superior plants in native plant species for unstable coastal areas. A significant component of this activity involves use of DNA technology through characterization and combining of useful genes in important coastal plant species. Following are a few activities involving application of this new molecular tool to help conserve and exploit the existing genetic resources for coastal restoration efforts.

DNA in Coastal Plants

Smooth cord grass, the dominant plant species of the Louisiana marshes, was our first target. We collected 126 smooth cord grass accessions from 11 parishes in south Louisiana and evaluated for both vegetative and reproductive traits; several superior accessions were selected for detailed evaluation. Forty selected accessions were also DNA fingerprinted to gather first-hand knowledge about the distribution of genetic diversity among the native accessions. A DNA fingerprint is a banding pattern unique to an individual organism.

Several accessions with distinct genetic patterns have been selected and crossed in a breeding program to develop genetically superior populations for coastal vegetation activities. The genetic variability revealed through our analysis will enable identification and incorporation of useful genes in desirable combinations using biotechnology.

In a related project, 43 surviving plants from brown marsh areas were sampled and subjected to DNA analysis to determine their genetic composition. Preliminary analysis indicates that these plants are quite different from the only released variety, Vermilion, in their genetic makeup. These plants will be a source of genes for breeding improved varieties of smooth cord grass.

Little is known about the performance and genetic purity of the seed-produced progeny of the clonally propagated Vermilion. Although clonal propagation is required to maintain genetic purity and provide quality assurance, it is also necessary to reduce the cost of coastal vegetation projects. Our research, using DNA markers, will determine if the seed-propagated plants maintain both genetic integrity and performance comparable to Vermilion.

Sea oats, once abundant on the Louisiana coast, help build sand dunes. A collection of sea oat germplasm from several Gulf and Atlantic states from Texas to Virginia has been assembled and is being analyzed. Seed yield is low in southern sea oats compared to northern accessions and has been a major limitation for use in beach nourishment projects. Genetic shuffling of DNA from these two sources can lead to development of sea oats that can adapt to low elevation Louisiana beaches.

Designing Native Plants

DNA technology has demonstrated its usefulness as a selection tool in applied crop improvement. Techniques have been developed to identify DNA that controls a specific attribute. Previously, breeders used visual or field screening to select dream plants. Now, DNA markers make it possible to much more accurately choose superior plants, speeding the overall process of genetic improvement. This process is sometimes referred to as marker-assisted selection.

LSU AgCenter scientists are also making progress in developing technology for aerial seeding for large marsh plantings. Unfortunately, smooth cord grass does not produce many seeds, and the seeds have poor storability. To make the aerial seeding of smooth cord grass a viable proposition, a series of technologies including DNA techniques are being employed to improve the seed yield and storability. As the project advances, we intend to target traits like vegetative vigor and extend them to sea oats. Our research will also expand to other coastal plant species including Spartina patens, bitter panicum and mangroves, to name a few that have proven potential in maintaining the coastal ecosystem. 

Adequate vegetative cover of the coastal marshes through the introduction of genetically diverse plant materials is needed to prevent disintegration. Discovery of the natural assemblage of genes, their role and reconfiguration in native plant species to improve their adaptation, survival, propagation and productivity will continue to be an LSU AgCenter research goal.

(This article appeared in the fall 2003 issue of Louisiana Agriculture.)