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expand all sections collapse all sections  Zea mays subsp. mays Gene "vp1"
ID 836
Name vp1 (GENE SYMBOL)
Synonyms (5)
GRAMENE GENEGR:0200567
Type Gene
Species Zea mays subsp. mays (Maize) [ GR_tax:014546 ]
Germplasm
Description Embryo fails to become dormant, viable if transplanted; some alleles dormant;
chlorophyll and carotenoids unaffected; anthocyanins in aleurone suppressed (aka
vp4); cDNA. Mutant kernels germinate before ear matures (viviparous); carotenoid
and abscisic acid levels are normal while aleurone anthocyanins are suppressed
(colorless kernel on colored A1 C1 R1 ear) except in the presence of sunlight
(opened husks). Some alleles are not viviparous but still show anthocyanin
suppression. Mutant embryos can be rescued by removal before ear dries and will
grow to maturity as normal plants. These embryos are insensitive to exogenous
abscisic acid. The normal dominant Vp1 allele codes for a trans-acting protein,
but it is expressed only in embryo, scutellum and aleurone tissues. Both the Vp1
protein and abscisic acid must be present to induce C1 transcription (Smith and
Cobb 1989 MNL63:57); vp1 encodes a protein with properties of a transcriptional
activator. (J.D. Smith; D. McCarty). Vivipary is the continuous development of a
plant body from its unicellular inception to maturity, without the intervention
of a period of dormancy. The term primitive sporophyte was initially used
(Eyster 1924) because the sporophytes of all non-seed-bearing plants, which
presumably are more primitive than seed-bearing plants, are normally viviparous.
Maize embryos normally become dormant in the seed stage and remain so until
conditions favorable for growth are provided. Viviparous kernels continue to
grow as long as there is enough moisture in the endosperm and cob to permit it
(Eyster 1924, Am. Nat. 58:436). A factor called "germinating seeds" was describ
ed by Mangelsdorf (1923), as having been first observed by Jones on a self-
pollinated ear of a small New England variety, Canada Flint. "It is not at all
unusual, especially in New England, to find ears in the field on which part of
the seeds have germinated. Ordinarily when this occurs the germinating seeds are
confined to a local region of the ear which has not dried out thoroughly." The
factor was expressed as random scattering of germinating seeds. When normal
seeds for this ear were planted the abnormality again appeared. This gene was
originally curated in MaizeGDB Database and the map position was displayed on
the maize bins map if feasible.
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