A novel glycine-rich protein is associated with starch grain accumulation during anther development

LIM14, originally identified as a lily gene associated with microsporogenes is, encodes a protein which has two distinct domains, one with glycine-seri ne repeats and the other with a hydrophobic signal peptide at the N-terminu s, The putative LIM14 protein, however, is distinct from the glycine-rich c ell wall proteins which have been described before. RNA analyses indicated that the LIM14 transcript is specifically detected in the anther from zygot ene to young pollen stage. By using antibodies raised against recombinant L IM14 protein, we detected anther-specific 15 kDa protein. Immunofluorescenc e microscopy demonstrated that the LIM14 protein is associated with starch grains in the anther wall cells just prior to microspore mitosis and then a ccumulates at a higher level with the starch grains of immature pollen. We tagged LIM14 with the GUS and GFP reporter genes and introduced them into t obacco BY-2 cells. Analysis of the transformed cells revealed that the chim eric proteins are functional and specifically targeted to plastids, These r esults indicate that LIM14 is an anther-specific protein that may play a ro le in starch accumulation and amyloplast differentiation during anther deve lopment and pollen formation.