Characterization of a Bacterial Contaminant in Loblolly Pine Tissue Culture

Bacterial contamination of immature seed explants can decrease the efficiency in initiating and establishing pine embryogenic cultures. A type of contaminant commonly observed surrounding the megagametophyte explant of immature loblolly pine (Pinus taeda L.) appears as a white to creamy halo on the surface or within the culture medium. This contaminant appears within 24-48 hours after culturing the immature seed. The severity of the contamination varies by year and family. The pattern of contamination among seeds pooled from several cones did not suggest operator technique as the source of contamination. Tests with seeds separated by cone during sterilization and culture suggest that the source of the contamination was from seeds of specific cones. To better understand the causal bacterium and provide insight to help prevent or decrease the occurrence of contamination, several isolates taken from different contaminated explants were identified. This identification was done by PCR amplification of a 500bp sequence of a 16S ribosomal RNA gene. The closest match in terms of sequence similarity was Erwinia amylovora. Erwinia species are the causal agents of several economically important diseases. For example, fire blight (E. amylovora) in the Roseaceae family that affects apple and pear trees, and soft rot (E. carotovora) in several crops including potato. Our results suggest that Erwinia may also infect immature loblolly pine seeds and is a probable causal agent of this type of bacterial contamination in pine tissue culture. We have been able to significantly reduce the negative impact of this contamination and increase culture establishment efficiency by separating seeds by cone for sterilization and culture.Papers and abstracts from the 27th Southern Forest Tree Improvement Conference held at Oklahoma State University in Stillwater, Oklahoma on June 24-27, 2003

Electrochemical Oxidative Fluorination of an Oxide Perovskite

We report on the electrochemical fluorination of the A-site vacant perovskite ReO3 using high-temperature solid-state cells as well as room-temperature liquid electrolytes. Using galvanostatic oxidation and electrochemical impedance spectroscopy, we find that ReO3 can be oxidized by approximately 0.5 equiv of electrons when in contact with fluoride-rich electrolytes. Results from our density functional theory calculations clearly rule out the most intuitive mechanism for charge compensation, whereby F-ions would simply insert onto the A-site of the perovskite structure. Operando X-ray diffraction, neutron total scattering measurements, X-ray spectroscopy, and solid-state 19F NMR with magic-angle spinning were, therefore, used to explore the mechanism by which fluoride ions react with the ReO3 electrode during oxidation. Taken together, our results indicate that a complex structural transformation occurs following fluorination to stabilize the resulting material. While we find that this process of fluorinating ReO3 appears to be only partially reversible, this work demonstrates a practical electrolyte and cell design that can be used to evaluate the mobility of small anions like fluoride that is robust at room temperature and opens new opportunities for exploring the electrochemical fluorination of many new materials

Transgenic Loblolly Pine Trees from Diverse Elite Families

Loblolly pine (Pinus taeda L.) has been the focus of genetic improvement for nearly 100 years because of the value of this species to the forestry industry. The application of gene transfer technology to loblolly pine improvement has been limited by the regeneration of transgenic tissue into plants. We have developed gene transfer systems that allow the regeneration of trees after the transformation of embryogenic cultures from a large number of genetically diverse families. Genetic transformation was achieved by biolistic and Agrobacterium-mediated techniques. Biolistic transformation efficiency was increased by identifying the optimal target using secondary somatic embryogenesis and by determining the long-term effects of tissue culture manipulations. Improvements to selection and the tissue culture system facilitated the production of stable transformants from 72% of the cell lines attempted from 15 elite families, with an escape rate of less than 1%. Molecular analysis of transgenic trees produced from biolistic transformation found that 36% of the trees had three inserts or less. Transgenic trees produced by biolistics have exhibited normal morphology for up to five growing seasons, to date. An Agrobacterium-mediated transformation system was developed for loblolly pine using tissue culture and selection procedures of the biolistic system. Agrobacterium tumefaciens has been used to produce transgenic trees of clones from elite loblolly families, as well as clones of P. radiata and P. taeda x rigida. Genomic blot analysis of Agrobacterium-transformed somatic embryos is ongoing. Field tests with Agrobacterium-transformed loblolly and the hybrid loblolly have been established each year since 2001. The efficiency of the Agrobacterium transformation system has made it possible for ArborGen to scale-up for high-throughput gene testing in a conifer. Transgenic trees have been produced with genes for lignin modification, accelerated growth, and flowering control.Papers and abstracts from the 27th Southern Forest Tree Improvement Conference held at Oklahoma State University in Stillwater, Oklahoma on June 24-27, 2003

Project advisory committee subcommittee on Forest Genetics

"October 26-27, 1988."Mass clonal propagation of improved conifers: project 3223 / Becwar ... [et al.] ; Biochemistry of clonal propagation: project 3223-2 / Feirer, Johnson ; Mass clonal propagation of improved hardwoods: project 3223-3 / Dinus, Nagmani, Uddin -- Handouts

High altitude studies of natural, supplemental and deletion of UV-B on vegetables and wheat : final report /

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