Gene encoding short integuments and uses thereof

Details Gene encoding short integuments and uses thereof Gene encoding short integuments and uses thereof

2000-06-09

2004-05-18

Shukla, Ram R. (Department: 1635)

Multicellular living organisms and unmodified parts thereof and

Method of introducing a polynucleotide molecule into or...

C435S006120, C435S091100, C435S458000, C536S023600, C536S024500, C800S298000

Reexamination Certificate

active

06737561

ABSTRACT:

FIELD OF THE INVENTION
The invention relates to short integuments1 nucleic acids and proteins, and to plants having altered phenotypes when transformed with short integumentsl nucleic acids.
BACKGROUND OF THE INVENTION
According to recent estimates, the global demand for crop plants such as rice, wheat, and maize should increase by 40% by 2020. It is thought that classical plant breeding technology, which led to the green revolution in the late 1960s, will contribute less and less to meet this increasing demand, whereas plant genetic engineering will contribute increasingly more. An important thrust area in plant genetic engineering is the identification and use of genes implicated in asexual production of seeds, or “apomixis.” Apomixis is thought to be an agronomically desirable trait that should enable seed companies and farmers to lock-in a favorable combination of genes for maximum grain yield without having to lose the gene combination in the next sexual generation. Genes for apomixis have not yet been identified. It is thought that genes that are generally important for very early embryo/seed development may be important for apomixis. A second important thrust is the production of early flowering varieties of plants such that breeding time can be reduced.
The evolution of flowering plants may have entailed a modification of primitive leaf or leaf-like structures that contained naked ovules on their surfaces, to specify floral organs that ultimately evolved to surround the ovules (Herr, “The Origin of the Ovule,”
Am. J. Bot.
82:547-564 (1995); Stebbins,
Flowering Plants: Evolution Above the Species Level,
Cambridge, Mass.: Harvard University Press, pp. 199-245). This view of angiosperm evolution predicts that the genetic regulatory network that controls ovule development should be interlaced with that which triggers flowering. Ovule, as the precursor of seed, is the link to the next generation. Genetic regulatory pathways that are important for early vegetative development of the embryo inside the ovule, for late reproductive development leading to the production of ovules, and for morphogenesis of the haploid female gametophyte, are crucial areas of investigation which can lead to enhanced agricultural practices.
Several genes important for ovule development have been identified in
Arabidopsis thaliana
(Reiser et al., “The Ovule and the Embryo Sac,”
The Plant Cell
5:1291-1301 (1993)). BELL1, a so-called cadastral gene that encodes a homeodomain protein (Reiser et al., “The BELL1 Gene Encodes a Homeodomain Protein Involved in Pattern Formation in the Arabidopsis Ovule Primordium,”
Cell
83, 735-742 (1995)), controls the expression of the floral organ identity gene AG within the ovule and thereby controls morphogenesis of ovule integuments (Modrusan et al., “Homeotic Transformation of Ovules into Carpel-Like Structures in Arabidopsis,”
The Plant Cell
6:333-349 (1994); Ray et al., “The Arabidopsis Floral Homeotic Gene BELL (BEL1) Controls Ovule Development Through Negative Regulation of AGAMOUS (AG) Gene,”
Proc. Natl. Acad. Sci. USA
91:5761-5765 (1994)). SUPERMAN, another cadastral gene that restricts the spatial expression pattern of the floral organ identity gene AP3 (Sakai et al., “Role of SUPERMAN in Maintaining Arabidopsis Floral Whorl Boundaries,”
Nature
378:199-203 (1995)), is important in ovule integument development (Gaiser et al., “The Arabidopsis SUPERMAN Gene Mediates Asymmetric Growth of the Outer Integument of Ovules,”
The Plant Cell
7:333-345 (1995)). The organ identity gene AP2 is also known to control ovule morphogenesis (Modrusan et al., “Homeotic Transformation of Ovules into Carpel-Like Structures in Arabidopsis,”
The Plant Cell
6:333-349 (1994)). By contrast, no known meristem identity or flowering control gene had, until now, been demonstrated to have a role in ovule development.
A gene termed SHORT INTEGUMENTS1 (SIN1), genetically detected in the model plant
Arabidopsis thaliana
by mutational studies has been determined to be an important regulatory gene for plant reproductive development. The SIN1 gene is required for normal ovule development (Lang et al., “sin1, A Mutation Affecting Female Fertility in Arabidopsis, Interacts with mod1, its Recessive Modifier,”
Genetics
137:1101-1110 (1994); Reiser et al., “The Ovule and the Embryo Sac,”
The Plant Cell
5:1291-1301 (1993); Robinson-Beers et al., “Ovule Development in Wild-Type Arabidopsis and Two Female Sterile Mutants,”
Plant Cell
4:1237-1250 (1992)). The original isolate of the sin1 mutation (sin1-1 allele) was identified as one causing a female sterile phenotype (Robinson-Beers et al., “Ovule Development in Wild-Type Arabidopsis and Two Female Sterile Mutants,”
Plant Cell
4:1237-1250 (1992)). Ovules of the original isolate have short integuments and a defective megagametophyte (see Reiser et al., “The Ovule and the Embryo Sac,”
The Plant Cell
5: 1291-1301 (1993)) for a review on ovule structure; Baker et al., “Interactions Among Genes Regulating Ovule Development in
Arabidopsis thaliana,” Genetics
145:1109-1124 (1997), for a recent genetic analysis; Schneitz et al., “Dissection of Sexual Organ Ontogenesis: A Genetic Analysis of Ovule Development in
Arabidopsis thaliana,” Development
124:1367-1376 (1997), for a summary of the known mutants affected in ovule development). It has been shown that the originally-described Sin1
−
mutant phenotype is a result of an interaction between sin1, and mod1, its recessive modifier (Lang et al., “sin1, A Mutation Affecting Female Fertility in Arabidopsis, Interacts with mod1, Its Recessive Modifier,”
Genetics
137:1101-1110 (1994)), and that mod1 is erecta, a mutation in a putative serine-threonine receptor protein kinase gene. The sin1-1 or sin1-2 mutation acting alone causes a defect in the coordination of growth of the two sheets of cells of the inner and outer integuments. All other originally described effects on the ovule, such as the lack of outer integument cell expansion and arrest of the megagametophyte, are due to secondary genetic interactions with erecta. There are several prospective protein phosphorylation sites within the SIN1 protein, and these might be substrates of protein kinases, such as the ERECTA product (Torii et al., “The Arabidopsis ERECTA Gene Encodes a Putative Protein Kinase with Extracellular Leucine-Rich Repeats,”
Plant Cell
8:735-746 (1996)).
In plants homozygous for the weaker sin1-2 mutant allele, approximately 40% of all ovules in any flower mature into seeds. But these seeds frequently contain embryos arrested at different stages of development, some of which germinate to produce abnormal seedlings. Genetic analysis shows that the maternal expression of the SIN1 gene is necessary for embryo development (Ray et al., “Maternal Effects of the Short Integument Mutation on Embryo Development in Arabidopsis,”
Dev. Biol.
180:365-369 (1996)).
Not only does this gene function in the formation of seeds, SIN1 is the only identified plant gene whose maternal expression is important for pattern formation in the zygotic embryo (Ray et al., “Maternal Effects of the Short Integument Mutation on Embryo Development in Arabidopsis,”
Dev. Biol.
180:365-369 (1996)). Both sin1-1 and sin1-2 alleles have the maternal-effect embryonic lethality phenotype (Ray et al., “Maternal Effects of the Short Integument Mutation on Embryo Development in Arabidopsis,”
Dev. Biol.
180:365-369 (1996)). The wild type SIN1 allele when transmitted through the pollen is unable to rescue the deleterious effects on embryogenesis of a homozygous maternal sin1-2 mutation. Ray et al. have shown that a wild type allele of SIN1 in the endosperm cannot rescue the maternal-effect of sin1-2 (Ray et al., “Maternal Effects of the Short Integument Mutation on Embryo Development in Arabidopsis,”
Dev. Biol.
180:365-369 (1996)). This is the first demonstration of a maternal effect embryonic pattern formation gene in a plant.
In
Arabidopsis thaliana,
meristem development progresses through at least three distinct phases: from vegetati

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