Maize ROP2 GTPase provides a competitive advantage to the male gametophyte

Genetics. 2003 Dec;165(4):2137-51.


Rop GTPases have been implicated in the regulation of plant signal transduction and cell morphogenesis. To explore ROP2 function in maize, we isolated five Mutator transposon insertions (rop2::Mu alleles). Transmission frequency through the male gametophyte, but not the female, was lower than expected in three of the rop2::Mu mutants. These three alleles formed an allelic series on the basis of the relative transmission rate of each when crossed as trans-heterozygotes. A dramatic reduction in the level of ROP2-mRNA in pollen was associated with the three alleles causing a transmission defect, whereas a rop2::Mu allele that did not result in a defect had wild-type transcript levels, thus confirming that mutation of rop2 causes the mutant phenotype. These data strongly support a role for rop2 in male gametophyte function, perhaps surprisingly, given the expression in pollen of the nearly identical duplicate gene rop9. However, the transmission defect was apparent only when a rop2::Mu heterozygote was used as the pollen donor or when a mixture of wild-type and homozygous mutant pollen was used. Thus, mutant pollen is at a competitive disadvantage compared to wild-type pollen, although mutant pollen grains lacked an obvious cellular defect. Our data demonstrate the importance in vivo of a specific Rop, rop2, in the male gametophyte.

Publication types

  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Alleles
  • Amino Acid Sequence
  • Base Sequence
  • DNA Transposable Elements / genetics
  • Heterozygote
  • Homozygote
  • Molecular Sequence Data
  • Mutation / genetics*
  • Phenotype
  • Plants, Genetically Modified / enzymology
  • Plants, Genetically Modified / growth & development
  • Pollen / genetics*
  • RNA, Messenger / genetics
  • RNA, Messenger / metabolism
  • RNA, Plant / genetics
  • Reverse Transcriptase Polymerase Chain Reaction
  • Sequence Homology, Amino Acid
  • Zea mays / enzymology
  • Zea mays / growth & development*
  • rho GTP-Binding Proteins / genetics
  • rho GTP-Binding Proteins / metabolism*


  • DNA Transposable Elements
  • RNA, Messenger
  • RNA, Plant
  • rho GTP-Binding Proteins

Associated data

  • GENBANK/AF126053
  • GENBANK/AF163377
  • GENBANK/AF163378
  • GENBANK/AF163379