title: Control of Anther Cell Differentiation by the Small Protein Ligand TPD1 and Its Receptor EMS1 in Arabidopsis.
abstract: A fundamental feature of sexual reproduction in plants and animals is the specification of reproductive cells that conduct meiosis to form gametes, and the associated somatic cells that provide nutrition and developmental cues to ensure successful gamete production. The anther, which is the male reproductive organ in seed plants, produces reproductive microsporocytes (pollen mother cells) and surrounding somatic cells. The microsporocytes yield pollen via meiosis, and the somatic cells, particularly the tapetum, are required for the normal development of pollen. It is not known how the reproductive cells affect the differentiation of these somatic cells, and vice versa. Here, we use molecular genetics, cell biological, and biochemical approaches to demonstrate that TPD1 (TAPETUM DETERMINANT1) is a small secreted cysteine-rich protein ligand that interacts with the LRR (Leucine-Rich Repeat) domain of the EMS1 (EXCESS MICROSPOROCYTES1) receptor kinase at two sites. Analyses of the expressions and localizations of TPD1 and EMS1, ectopic expression of TPD1, experimental missorting of TPD1, and ablation of microsporocytes yielded results suggesting that the precursors of microsporocyte/microsporocyte-derived TPD1 and pre-tapetal-cell-localized EMS1 initially promote the periclinal division of secondary parietal cells and then determine one of the two daughter cells as a functional tapetal cell. Our results also indicate that tapetal cells suppress microsporocyte proliferation. Collectively, our findings show that tapetal cell differentiation requires reproductive-cell-secreted TPD1, illuminating a novel mechanism whereby signals from reproductive cells determine somatic cell fate in plant sexual reproduction.
authors.affiliation: Department of Biological Sciences, University of Wisconsin-Milwaukee, Milwaukee, Wisconsin, United States of America.
authors.forename: Jian
authors.initials: J
authors.lastname: Huang
authors.affiliation: Department of Biological Sciences, University of Wisconsin-Milwaukee, Milwaukee, Wisconsin, United States of America.
authors.forename: Tianyu
authors.initials: T
authors.lastname: Zhang
authors.affiliation: Department of Biological Sciences, University of Wisconsin-Milwaukee, Milwaukee, Wisconsin, United States of America.
authors.forename: Lisa
authors.initials: L
authors.lastname: Linstroth
authors.affiliation: Department of Biological Sciences, University of Wisconsin-Milwaukee, Milwaukee, Wisconsin, United States of America.
authors.forename: Zachary
authors.initials: Z
authors.lastname: Tillman
authors.affiliation: Department of Botany, University of Wisconsin-Madison, Madison, Wisconsin, United States of America.
authors.forename: Marisa S
authors.initials: MS
authors.lastname: Otegui
authors.affiliation: Department of Biological Sciences, University of Wisconsin-Milwaukee, Milwaukee, Wisconsin, United States of America.
authors.forename: Heather A
authors.initials: HA
authors.lastname: Owen
authors.affiliation: Department of Biological Sciences, University of Wisconsin-Milwaukee, Milwaukee, Wisconsin, United States of America.
authors.forename: Dazhong
authors.identifier: 0000-0001-9167-1421
authors.initials: D
authors.lastname: Zhao
mesh_terms: D017360:Arabidopsis / Q000235:genetics / Q000254:growth & development; D029681:Arabidopsis Proteins / Q000235:genetics* / Q000378:metabolism; D002453:Cell Cycle / Q000235:genetics; D002454:Cell Differentiation / Q000235:genetics*; D035264:Flowers / Q000166:cytology / Q000235:genetics* / Q000254:growth & development; D018506:Gene Expression Regulation, Plant; D008024:Ligands; D011058:Pollen / Q000235:genetics / Q000254:growth & development; D011494:Protein Kinases / Q000235:genetics* / Q000378:metabolism; D012639:Seeds / Q000235:genetics / Q000254:growth & development
chemical_list: D029681:Arabidopsis Proteins; D008024:Ligands; D011494:Protein Kinases; C483722:Tapetum determinant1 protein, Arabidopsis; C464786:At5g07280 protein, Arabidopsis