Morphological analysis of female gametophyte development in thebel1 stk shp1 shp2mutant

In Arabidopsis thaliana, cell fate in developing ovules is determined by the action of the homeodomain factor BELL1 (BEL1)\r\nand of the MADS-box factors SEEDSTICK (STK), SHATTERPROOF1 (SHP1) and SHP2. The analysis of the bel1 and\r\nthe stk shp1 shp2 mutants revealed that the functional megaspore is formed, however, it does not proceed into\r\nmegagametogenesis. In the bel1 stk shp1 shp2, quadruple mutant megasporogenesis does not take place. In this article we\r\ndescribe a detailed morphological analysis of the quadruple mutant, and we discuss the possibility that BELL1, STK, SHP1\r\nand SHP2 not only control integument identity determination and development, but that they might also play a role during\r\nmegasporogenesis.