A protective role for the embryo surrounding region of the maize endosperm, as evidenced by the characterisation of ZmESR-6, a defensin gene specifically expressed in this region.
A Zea mays cDNA clone, ZmESR-6, was isolated as a gene specifically expressed at the basal region of immature kernels. ZmESR-6 cDNA encoded for a small (11.1 kDa) protein homologous to plant defensins. As for other defensins, the protein contained an N-terminal signal peptide signature and a C-terminal acidic peptide, the mature peptide has a molecular mass of 5.5 kDa. ZmESR-6 was highly expressed in developing kernels but the transcript could not be detected in any other maize tissue. The recombinant ZmESR-6 protein, purified from E. coli, showed strong in vitro inhibitory activity against bacterial and fungal plant pathogens, suggesting a role for ZmESR-6 in plant defence. The distribution of the transcripts was restricted to the embryo surrounding region (ESR) of the kernel. Immunolocalisation experiments revealed, however, that at the grain filling phase ZmESR-6 was accumulated in the placentochalaza-cells, rather than in the ESR cells that produce it. Our results suggest that the ESR has a role in protecting the embryo at the very early stages of seed development, whilst contributes to the general defence mechanism of the kernel at later developmental stages.
Balandín
Maite
M
Departamento de Biología Celular y Genética, Universidad de Alcalá, Madrid, Spain.
Royo
Joaquín
J
Gómez
Elisa
E
Muniz
Luis M
LM
Molina
Antonio
A
Hueros
Gregorio
G
D000595:Amino Acid Sequence; D000890:Anti-Infective Agents / Q000494:pharmacology; D001419:Bacteria / Q000187:drug effects / Q000254:growth & development; D001483:Base Sequence; D015152:Blotting, Northern; D015153:Blotting, Western; D018076:DNA, Complementary / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification; D023082:Defensins / Q000235:genetics* / Q000378:metabolism / Q000494:pharmacology; D005658:Fungi / Q000187:drug effects / Q000254:growth & development; D018507:Gene Expression Regulation, Developmental; D018506:Gene Expression Regulation, Plant; D007150:Immunohistochemistry; D017403:In Situ Hybridization; D020128:Inhibitory Concentration 50; D008969:Molecular Sequence Data; D010940:Plant Proteins / Q000235:genetics* / Q000378:metabolism / Q000494:pharmacology; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D011994:Recombinant Proteins / Q000378:metabolism / Q000494:pharmacology; D012639:Seeds / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid; D003313:Zea mays / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism
D000890:Anti-Infective Agents; D018076:DNA, Complementary; D023082:Defensins; D010940:Plant Proteins; D012333:RNA, Messenger; D011994:Recombinant Proteins