OsCRTISO,ZEBRA2,MHZ5,MIT3

| Categories genes  | Tags oxidative  photosynthesis  ABA  ethylene  ABA  ethylene response  seedlings  ethylene production  tillering  tiller  development  map-based cloning  tiller number 
  • Information
  • Publication
  • Genbank accession number
  • Key message
    • The greatly increased activities of reactive oxygen species (ROS) scavenging enzymes, and reduced photosystem (PS) II core proteins CP43, CP47 and D1 in leaves of the Oscrtiso/phs3-1mutant and OsLCY RNAi transgenic rice indicated that photo-oxidative damage occurred in PS II, consistent with the accumulation of ROS in these plants
    • Expression analysis via both RT-PCR and ZEBRA2-promoter-beta-glucuronidase (GUS) transgenic rice indicates that ZEBRA2 is predominantly expressed in mesophyll cells of mature leaves where active photosynthesis occurs
    • More severe phenotype of the zebra2 mutant under high light intensity indicates that ““zebra”” phenotype might be caused by photooxidative damages
    • We found that MHZ5 encodes a carotenoid isomerase and that the mutation in mhz5 blocks carotenoid biosynthesis, reduces ABA accumulation, and promotes ethylene production in etiolated seedlings
    • ABA can largely rescue the ethylene response of the mhz5 mutant
    • Ethylene induces MHZ5 expression, the production of neoxanthin, an ABA biosynthesis precursor, and ABA accumulation in roots
    • MHZ5 overexpression results in enhanced ethylene sensitivity in roots and reduced ethylene sensitivity in coleoptiles
    • Prolycopene was accumulated while all-trans-lycopene was barely detectable in the dark-grown mit3 seedlings
    • Exogenously applied GR24, a synthetic SL, could rescue the tillering phenotype of mit3
    • Our results reveal that the tillering phenotype of mit3 is due to SL deficiency and directly link carotenoid deficiency with SL-regulated rice tillering
    • Mutations in the MIT3 gene encoding a caroteniod isomerase lead to increased tiller number in rice.
    • Double mutant analysis of mit3 with the SLs biosynthesis mutant d17 revealed that MIT3 controls tiller development upstream of the SLs biosynthesis pathway
    • Map-based cloning revealed that MIT3 encodes a carotenoid isomerase (CRTISO), the key enzyme catalyzing the conversion from prolycopene to all-trans-lycopene in carotenoid biosynthesis
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