Maternal Effects of theshort integumentMutation on Embryo Development inArabidopsis

Abstract

Maternal gene products deposited in an animal egg determine the polarity of embryonic axes and regulate embryonic cell–cell communication important for morphogenesis. Here we report the first maternal-effect embryo-defective mutation discovered in a plant. Recessive mutations in theSHORT INTEGUMENT(SIN1) gene inArabidopsiswere previously shown to influence ovule development and flowering time. Here we show that asin1mutation has a pronounced maternal effect on zygotic embryo development. A homozygoussin1mutant embryo is normal when nursed by asin1/+ heterozygous maternal sporophyte. Strikingly, asin1or asin1/+ embryo that is nursed by asin1homozygous maternal sporophyte develops morphogenetic defects in the apical–basal and radial axes. The defects resemble those seen in some zygotic-effect embryonic pattern formation mutants. These results imply that in maternal cells theSIN1gene either codes for or controls the production of a diffusible morphogen necessary for proper zygotic embryogenesis.