Abstract
Arabidopsis has two genes encoding HMG-CoA reductase, HMG1 and HMG2. To understand the roles of these genes, we have isolated hmg1 and hmg2 mutants. hmg1 mutant showed dwarf, early senescence and sterile phenotypes. These pleiotropic phenotypes are involved in different triterpenes. However, hmg2 mutant show no phenotypes under the normal growth condition. We tried to produce hmg1 hmg2 double mutants, however, we could not obtain the double mutant in the self-pollinated seeds from HMG1/hmg1 hmg2/hmg2 plants. Crossing experiments using different hmg1 allele showed that the development of hmg1 hmg2 male gametes was abnormal. hmg1 HMG2 male gametes were normal in hmg1 heterozygous plants, but were abnormal in hmg1 homozygous plants due to the deficiency of sterols from parental cells. HMG2 hmg1 male gametes were normal. These results suggest that either HMG1 or HMG2 is necessary for the pollen development and HMG1 in parents is essential for the supply of sterols.
