The plant root system is responsible for the uptake of water, minerals, and nutrients. Roots have genetically controlled patterns of growth with respect to root system architecture, nutrient uptake and the response to other abiotic or biotic stressors. My thesis focuses on three areas in elucidating tomato and Arabidopsis root genetics. These include genes regulating root angle, natural variation in the tomato response to phosphate deprivation, and the creation of dominant mutant brassinosteroid transcription factor alleles in tomato. I contributed to the identification of two genes regulating root angle in Arabidopsis – PURPLE ACID PHOSPHATASE 27 (PAP27) and CELL DIVISION CYCLE 73 (CDC73) using data from a tomato Quantitative Trait Loci (QTL), Expression Quantitative Trait Loci (eQTL), and a Genome Wide Association Study (GWAS) T-DNA insertion alleles, and an overexpression line. I performed extensive phenotyping of the roots of two tomato species, Solanum lycopersicum and Solanum pennellii, in their response to phosphate deprivation. Here I characterized tomato root system architecture, root hair elongation, acid phosphatase activity, mineral elemental profiles, gene expression, iron redox state, and changes in response to zinc concentrations, in both sufficient and limiting phosphate conditions. I determined that the S. pennellii root system acts in a constitutive phosphate deprivation stressed manner in the presence of sufficient phosphate. This trait was partially controlled by an overaccumulation of zinc in the presence of sufficient phosphate but not in limiting phosphate. Finally, I created dominant mutant alleles of the brassinosteroid transcription factors SlBZR1a-D and SlBZR1b-D in tomato. These showed expression downregulation of known brassinosteroid catabolic genes in a homologous manner to Arabidopsis dominant mutant alleles bzr1-1D and bes1-D.
|Advisor:||Brady, Siobhan M.|
|Commitee:||Lucas, William J., Maloof, Julin|
|School:||University of California, Davis|
|School Location:||United States -- California|
|Source:||DAI-B 81/12(E), Dissertation Abstracts International|
|Subjects:||Plant sciences, Genetics|
|Keywords:||Root genetics, Phosphate deprivation, Gravitropism|
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