DUGi

Adventitious root induction by hysparin in Arabidopsis thaliana

http://dugi.udg.edu/item/http:@@@@hdl.handle.net@@10256@@14425

Adventitious rooting is important process because it is a critical step during the propagation of plant cuttings and clonal propagation of many crops and ornamental species. It also plays an important role in the life of plant to help it survive for example damage to its root system or in some species it contributes to vegetative propagation. In the genetic model plant Arabidopsis, adventitious roots (AR) emerge from the hypocotyl when plants have been exposed to a dark period and subsequently are transferred to the light. These conditions induce 1 to 2 AR. The number of ARs on the hypocotyl dramatically increased when plants are treated with the plant hormone auxin. In Prof. Danny Geelen’s research group, a small molecule screen identified a compound called hysparin that is highly effective in inducing AR (±35 AR), without changing the architecture of the root system. The aim of this project is to determine which genetic factors are involved in hysparin action. To achieve this, forward and reverse genetics experiments were realized. The forward genetic experiment involved the screening of a population of EMS mutagenized Arabidopsis Columbia-0 lines. M2 offspring of these mutants were treated with hysparin, and analyzed for the induction of AR. Plants were considered reduced in hysparin response when less than 6 AR were counted. The M3 progeny of candidate hysparin insensitive lines were rescreened for hysparin response and segregation of the mutant phenotype was assessed. Next, the homozygous mutant lines were tested for their sensitivity to synthetic auxins before the construction of mapping populations was started. In addition, a reverse genetic experiment was realized with knock out mutants of light receptors and regulated transcription factors that are known to play an important role in the de-etiolation process. By testing the mutant lines for their hysparin response, the role of the different factors in hysparin signaling was assessed. The data presented in this thesis does not allow us to draw conclusions on how hysparin induces AR. However, it does provide new tools in the form of mutants that are valuable for the identification of genetic elements involved in hysparin action