Abstract
CTP:PHOSPHORYLETHANOLAMINE CYTIDYLYLTRANSFERASE 1 (PECT1) is a gene encoding a rate-limiting enzyme of phosphatidylethanolamine biosynthesis in Arabidopsis. A null mutation, pect1-6, caused embryo abortion before the octant stage. However, reciprocal crosses revealed that pect1-6 caused no significant gametophytic defect. pect1-4/pect1-6 transheterozygotic plants were created by crossing pect1-6 heterozygotic plants with pect1-4 homozygotic plants, which showed moderate level of PECT activity. The transheterozygotic plants, whose PECT activity was decreased by 81 % when compared to that of the wild type, displayed severe dwarfism and low fertility. In these plants, anthers produced no or reduced volumes of pollen, and many ovules remained unfertilized, because of no or abnormal embryo sac development. Therefore, sufficient PECT activity is required for development of normal gametophytes in floral organs. In addition to these defects, partial lethality of pect1-4/pect1-6 embryos decreased seed production in the siliques of pect1-4/pect1-6 transheterozygotic plants.
