it's been a long day.

Grant proposals are done! Never wanna do that again! Yay 7-11 and apple juice slurpees!

Investigator: Eric L. Patterson

Performing Institution: The National Center for Germplasm Resources and Preservation

A Structural and Genetic Study of Arecaceae Embryos to Define Orthodoxy and Recalcitrance in Cryopreservation

Abstract

Cryogenic germplasm storage is quickly becoming one of the greatest resources for the preservation of agricultural and wild species. While many orthodox plants such as corn or wheat are easily stored, other important germplasms remain recalcitrant to storage because of seed water content, protein and lipid structure. Many species in both categories of storage behavior can be found in the Arecaceae (Palms). The Arecaceae are of large agricultural importance and offer seeds with diverse habits and life histories. Understanding the parameters and molecular basis of recalcitrance in palm seeds will help us optimize preservation conditions such as timing, temperature, and duration.

To identify and classify seeds that are recalcitrant, we have to define recalcitrance. To do this we will take embryos from a variety of palm seeds at a variety of developmental stages and analyze dry matter content via light and electron microscopy. We will be able to break up the palm seeds into groups that are orthodox, intermediate, and recalcitrant by their biochemical and visual traits. After classification, we will focus on the orthodox group and look for a molecular basis for their cryo-tolerance. We will develop microarrays with candidate genes identified in the oil-palm genome as well as more distantly related plants like rice and sugarcane. Then embryos can be screened at different developmental stages to find differential expression of the candidate genes. With this data we can begin to time dehydration and freezing of cryo-tolerant species of palm to optimize preservation and post-freezing germination.

A Test of the Complexity Hypothesis for the Continued Existence of the Chloroplast Genome

Investigator: Margaret B. Fleming

Institution: Colorado State University, Department of Biology

Abstract: The persistence of the chloroplast genome has long been an unexplained phenomenon, given that motive and means exist for chloroplast genes to relocate to the nucleus. Multiple hypotheses have been presented to explain this phenomenon, including the hydrophobic hypothesis, the Colocation of Redox Regulation hypothesis, and the complexity hypothesis. Briefly, the complexity hypothesis states that the evolution of photosynthesis prior to the endosymbiotic event permitted highly complex regulatory systems to develop. These systems, once transferred into the host cell, are unable to migrate to the nucleus because so many elements would be required to transfer at the same time. Such a mass migration would be prohibited by the laws of chance. I propose an experimental test of the complexity hypothesis by identification of a complete chloroplast gene regulatory network containing multiple elements (but a limited number of elements for the purposes of experimentation), followed by transfer of the DNA for the entire system to the nucleus. If the hypothesis is correct and the transfer is successful, there should be no deleterious phenotype related to this transfer, and possibly even an advantageous one will appear. This experiment will have relevance to genetic engineers as well as geneticists, since containment of genetic engineering constructs has long been proposed to prevent genetic drift, yet high rates of chloroplast DNA transfer to the nucleus occur. If complexity is a supportable hypothesis, a more complex insertion cassette in the chloroplast might be sufficient to contain the genetic modification.