The maize disorganized aleurone layer 1 and 2 (dil1, dil2) mutants lack control of the mitotic division plane in the aleurone layer of developing endosperm

The maize (Zea mays L.) endosperm consists of an epidermal like layer of isodiametric aleurone cells surrounding a central body of starchy endosperm cells. In disorgal1 (dil1) and disorgal2 (dil2) mutants the control of the mitotic division plane is relaxed or missing, resulting in mature grains with disorganized aleurone layers. In addition to orientation of the division plane, both the shape and size of the aleurone cells are affected, and often more than one layer of aleurone cells is present. Homozygous dil1 and dil2 grains are shrunken due to reduced accumulation of starchy endosperm and premature developmental arrest of the embryo, and mature mutant grains germinate at a very low rate and fail to develop into plants. However, homozygous mutant plants can be obtained through embryo rescue, revealing that both mutants have an irregular leaf epidermis as well as roots with a strongly reduced number of root hairs and aberrant root hair morphology. Our results suggest the presence of common regulatory mechanisms for the control of cell division orientation in the aleurone and plant epidermis.