A proteoglycan mediates inductive interaction during plant vascular development.
Inductive cell-cell interactions are essential for controlling cell fate determination in both plants and animals; however, the chemical basis of inductive signals in plants remains little understood. A proteoglycan-like factor named xylogen mediates local and inductive cell-cell interactions required for xylem differentiation in Zinnia cells cultured in vitro. Here we describe the purification of xylogen and cloning of its complementary DNA, and present evidence for its role in planta. The polypeptide backbone of xylogen is a hybrid-type molecule with properties of both arabinogalactan proteins and nonspecific lipid-transfer proteins. Xylogen predominantly accumulates in the meristem, procambium and xylem. In the xylem, xylogen has a polar localization in the cell walls of differentiating tracheary elements. Double knockouts of Arabidopsis lacking both genes that encode xylogen proteins show defects in vascular development: discontinuous veins, improperly interconnected vessel elements and simplified venation. Our results suggest that the polar secretion of xylogen draws neighbouring cells into the pathway of vascular differentiation to direct continuous vascular development, thereby identifying a molecule that mediates an inductive cell-cell interaction involved in plant tissue differentiation.
Motose
Hiroyasu
H
Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Hongo 7-3-1, Bunkyo-ku, Tokyo 113-0033, Japan. hmotose@ucdavis.edu
Sugiyama
Munetaka
M
Fukuda
Hiroo
H
D000595:Amino Acid Sequence; D052179:Antigens, Plant; D017360:Arabidopsis / Q000166:cytology / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D019659:Asteraceae / Q000166:cytology / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism*; D002352:Carrier Proteins / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism; D002450:Cell Communication; D002454:Cell Differentiation; D002478:Cells, Cultured; D017343:Genes, Plant / Q000235:genetics; D018519:Meristem / Q000166:cytology / Q000378:metabolism; D008969:Molecular Sequence Data; D009088:Mucoproteins / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism; D009154:Mutation / Q000235:genetics; D010641:Phenotype; D010940:Plant Proteins / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism; D017434:Protein Structure, Tertiary; D011509:Proteoglycans / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*
D052179:Antigens, Plant; D029681:Arabidopsis Proteins; D002352:Carrier Proteins; D009088:Mucoproteins; D010940:Plant Proteins; D011509:Proteoglycans; C006619:arabinogalactan proteins; C511920:lipid transfer proteins, plant; C487711:xylogen proteoglycan, Arabidopsis