Inheritance of azetidine-2-carboxylic acid resistance in Arabidopsis thaliana.
AuthorKhan, Rehana Akhter.
Committee ChairBohnert, Hans J.
MetadataShow full item record
PublisherThe University of Arizona.
RightsCopyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.
AbstractA number of hypotheses link salt tolerance in plants to proline accumulation or transport of proline. To begin to understand the genetic basis of this correlation, fifteen mutants of Arabidopsis thaliana were selected for resistance to the toxic proline analog, azetidine-2-carboxylic acid (ACA). These mutants were characterized by seedling growth and proline content on nutrient agar media in the absence and presence of ACA and NaCl. One of these ACA-resistant mutants, KG3, also showed enhanced tolerance to NaCl and was characterized by a recessive trait, transparent testa. Inheritance studies indicated that ACA resistance in KG3 was due to a single recessive gene mutation, named aca1. Genetic mapping studies were done by crossing KG3 with a morphological marker line W100 to determine the chromosomal location of ACa resistance in relation to known markers. Segregation analysis of 180 single-seed-descent F₃ families showed that aca1 was linked to marker tt3. Marker tt3 is located on chromosome V of Arabidopsis thaliana. Segregation of tt3 and aca1 did not show a 9:3:3:1 ratio, suggesting that aca1 was closely linked to tt3, located 62.1 cM from the end of chromosome V. The transparent testa phenotype of KG3 was complemented by locus tt4 also located on this chromosome. To determine the basis of enhanced NaCl tolerance in KG3, F₃ families from a cross between KG3 and Columbia pubescent wild type were tested for NaCl resistance. Families showing optimal growth after release from salt stress were scored for NaCl tolerance. Segregation analysis indicated that the salt tolerance in KG3 was due to a single recessive gene mutation called salt addicted (sad1). The sad1 phenotype appeared to have required NaCl for optimal growth. Segregation analysis of aca1 and sad1 phenotype showed that they were not linked. Molecular mapping of aca-1 was done by using a number of RFLP markers selected from all five Arabidopsis thaliana chromosomes. This study indicated that aca1 was linked with markers m331 and m435, located at positions 73.4 cM and 80.2 cM, respectively, on chromosome V on the unified map of Arabidopsis thaliana. Thus, the map location of aca1 was found to lie within 62 to 67 centimorgans on chromosome V.
Degree ProgramPlant Sciences