Start Date: Apr 09, 2007
End Date: Apr 08, 2012
1) Introgression of Reniform Nematode Resistance: Standard procedures for cotton flower emasculation and pollen transfer will be followed for backcross breeding. After each cross, progeny will be bioassayed for resistance to the reniform nematode, and the most highly resistant progeny will be retained for subsequent crossing, self seed generation, and DNA extraction for marker development. Plants will be grown under field conditions and evaluated for agronomic performance. Standard techniques and commercially available technology will be used for cotton DNA extraction. PCR amplification, electrophoresis, and fragment size detection will be utilized to identify molecular markers. 2) South Carolina Seed and Boll Rot: A mutagenesis system will be used to identify genes involved in production, regulation, and/or secretion of factors that cause boll rot. Based on these results, a set of predicted gene sequences associated with pathogenicity will be used to develop a PCR based method for detecting seed and boll rotting bacteria in field samples. Bolls from greenhouse grown plants will be used in initial testing to determine the efficacy of the developed amplification system. 3) Relation of Fusaric Acid to Virulence of Fusarium oxysporum f. sp. vasinfectum (F.o.v.): Biotypes of F.o.v. will be monitored for their ability to produce high levels of phytotoxins, and virulence of biotypes will be determined. The biosynthesis of those phytotoxins that correlate with virulence will be determined by feeding labeled substrates to the pathogens. Genes involved in the biosynthesis of these phytotoxins will be identified. Knock-out mutants will be generated to assess the role of specific phytotoxins in virulence and pathogenicity.