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Full-Text Articles in Life Sciences

Cercospora Leaf Blight Of Soybean: Pathogen Vegetative Compatibility Groups, Population Structure, And Host Resistance, Guohong Cai Jan 2004

Cercospora Leaf Blight Of Soybean: Pathogen Vegetative Compatibility Groups, Population Structure, And Host Resistance, Guohong Cai

LSU Doctoral Dissertations

Nitrogen nonutilizing mutants were used to assess vegetative compatibility of 58 isolates of Cercospora kikuchii, 55 of which were isolated from soybean plants in Louisiana. Only 16 of 56 self-compatible isolates were assigned to six multi-member vegetative compatibility groups (VCGs), 01-06, with two or three isolates in each VCG. The other 40 isolates were not vegetatively compatible with any isolates other than themselves. All six multi-member VCGs contained isolates from different soybean cultivars, and three included isolates from different locations. Only one VCG included isolates both from soybean leaves and from seeds, while two and three multi-member VCGs included isolates …


Tissue Culture And Transformation Of Introducing Genes Useful For Pest Management In Rice, Shuli Zhang Jan 2004

Tissue Culture And Transformation Of Introducing Genes Useful For Pest Management In Rice, Shuli Zhang

LSU Doctoral Dissertations

Sheath blight (SB), caused by Rhizoctonia solani K¨¹hn, is a major rice disease internationally and in the southern rice area of the Unites States, including Louisiana. Breeders have incorporated partial resistance into commercial rice varieties to control the disease, but a higher level of resistance is needed. It has been demonstrated that the pathogenesis-related (PR) proteins ¦Â-1, 3-glucanase and chitinase are components of effective defense mechanisms for protecting plants against fungal pathogens. This research was conducted to co-transform the ¦Â-1, 3-glucanase, chitinase and bar genes into the rice variety Taipei 309 using the hpt gene for resistance to hygromycin B …


Biology And Ecology Of Leptographium Species And Their Vectos As Components Of Loblolly Pine Decline, Lori G. Eckhardt Jan 2003

Biology And Ecology Of Leptographium Species And Their Vectos As Components Of Loblolly Pine Decline, Lori G. Eckhardt

LSU Doctoral Dissertations

Loblolly pine (Pinus taeda L.) decline (LPD) has been present in upland sites of central Alabama since the 1960s. Symptoms of LPD (fine root deterioration, short chlorotic needles, sparse crowns, reduced radial growth) begin in the 30-40 yr age class, resulting in premature death at ages 35-50. Previously, declining loblolly was diagnosed as littleleaf disease (LLD); however, site conditions associated with LPD are different from LLD sites. Littleleaf disease only occurs on eroded, heavy clay soils and is secondarily associated with the fungus, Phytophthora cinnamomi. In contrast, LPD occurs on sandy, well-drained soils and is associated with Leptographium spp., as …


Studies On Rice Transformation And The Use Of Transformed Plants [Electronic Resource], Qiming Shao Jan 2003

Studies On Rice Transformation And The Use Of Transformed Plants [Electronic Resource], Qiming Shao

LSU Doctoral Dissertations

This research was conducted to enhance utilization of the Liberty herbicide resistance transgene in rice. Non-lethal methods to determine the sensitivity of transgenic rice plants to hygromycin B and Liberty were developed, tested and used in this research. Four homozygous transformed plants were selected to make reciprocal crosses with their non-transformed parent cultivars Taipei 309 and Nipponbare. Their resistances to Liberty and hygromycin B were controlled by the closely linked single dominant genes bar and hpt. Some non-resistant phenotypes in the F2 populations were due to gene silencing. The bar gene in some of these plants were allelic and some …


Bollworm (Lepidoptera: Noctuidae) Ecology On Genetically Engineered Bollgard And Bollgard Ii Cottons, Jeffrey Gore Jan 2002

Bollworm (Lepidoptera: Noctuidae) Ecology On Genetically Engineered Bollgard And Bollgard Ii Cottons, Jeffrey Gore

LSU Doctoral Dissertations

The ecology of bollworms, Helicoverpa zea (Boddie), on Bollgard and Bollgard II cottons, Gossypium hirsutum L., was studied in field and laboratory experiments. Neonate bollworm larvae were placed on selected components of cotton squares and flowers from non-Bollgard, Bollgard, and Bollgard II cotton varieties. Larval survival was higher on flower anthers and square anthers than on other floral parts for each cultivar. Bollworm survival was lowest on all Bollgard II floral structures. To evaluate larval behavior on Bollgard cotton, first instar bollworms were placed on terminals of non-flowering and flowering cotton plants. Larvae were recovered lower on Bollgard cotton than …


Delayed Phytotoxicity Syndrome In Louisiana Rice Caused By The Use Of Thiobencarb Herbicide, Chiliang Chen Jan 2002

Delayed Phytotoxicity Syndrome In Louisiana Rice Caused By The Use Of Thiobencarb Herbicide, Chiliang Chen

LSU Doctoral Dissertations

Thiobencarb (TB), widely used for the control of broadleaf weeds, grasses, and sedges in rice fields, is considered safe for rice plants when used at recommended rates. TB's reductive dechlorination product, dechlorinated thiobencarb (DTB), is highly toxic to rice. TB is naturally transformed into DTB in field soils in certain areas in Japan and the United States. The resultant syndrome is called delayed phytotoxicity syndrome (DPS). This research was conducted to characterize DPS in Louisiana, to compare the toxicity of TB and DTB to rice, to determine uptake and retention rates of TB and DTB by rice, to confirm that …