The identification of genes controlling stamen tissue specification and differentiation in Arabidopsis thaliana

This thesis describes the generation and screening of an A. thaliana M2 population for mutant lines affected in stamen development. The strategy utilised, was to mutagenise transgenic A. thaliana seed, homozygous for either the A6 or A9 promoter linked to the GUS gene, using -irradiation. The temporal expression patterns of the A9 and A6 promoters were evaluated for their use as genetic markers to delimit windows along the stamen differentiation pathway, into which subsequently isolated mutants could be placed. The TMS2 gene was also evaluated for its use as a visual reporter gene to aid in the isolation of mutant lines. The resulting M2 population was screened to identify mutants of the stamen differentiation pathway, by assaying for the absence or reduction of GUS activity in the floral buds. Four non-allelic male sterile mutants were identified and characterised, namely gne1, gne2, gne4 and gne7. Observations of anther histology show the abnormal differentiation of the tapetum and middle layer cells in gne1 and gne4 and the abnormal specification of these two tissue types in gne2. The fourth mutant line, gne7, shows asynchronous microspore development. Genetic map positions were ascertained for gne1, gne2 and gne7 using the A. thaliana W100F multimarker line and CAPS analysis. Additionally, CAPS analysis revealed that the PHYC gene was deleted in the gne7 mutant. This thesis also examines the sense and antisense expression of the AG gene under the control of the A6 and A9 promoter, as well as the analysis of the A9 promoter by 5' deletion analysis.