Micropylar Pollen Tube Guidance by Egg Apparatus 1 of Maize

Márton, Mihaela L.; Cordts, Simone; Broadhvest, Jean; Dresselhaus, Thomas

doi:10.1126/science.1104954

Cited by 280 publications

(266 citation statements)

References 13 publications

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“…These late defects have often been interpreted as resulting from the abnormal structure of ig1 embryo sacs rather than from a requirement for ig1 in the female gametes per se. The synergids are known to attract pollen tubes (Higashiyama et al, 2001;Huck et al, 2003;Rotman et al, 2003;Marton et al, 2005), and the presence of extra synergids may promote the entry of extra pollen tubes into the embryo sac, leading to heterofertilization. Alternatively, ig1 may directly prevent these abnormal events by inhibiting embryogenesis in the egg cell until fertilization and karyogamy occur.…”

Section: Discussionmentioning

confidence: 99%

Theindeterminate gametophyte1Gene of Maize Encodes a LOB Domain Protein Required for Embryo Sac and Leaf Development

2007

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Angiosperm embryo sac development begins with a phase of free nuclear division followed by cellularization and differentiation of cell types. The indeterminate gametophyte1 (ig1) gene of maize (Zea mays) restricts the proliferative phase of female gametophyte development. ig1 mutant female gametophytes have a prolonged phase of free nuclear divisions leading to a variety of embryo sac abnormalities, including extra egg cells, extra polar nuclei, and extra synergids. Positional cloning of ig1 was performed based on the genome sequence of the orthologous region in rice. ig1 encodes a LATERAL ORGAN BOUNDARIES domain protein with high similarity to ASYMMETRIC LEAVES2 of Arabidopsis thaliana. A second mutant allele of ig1 was identified in a noncomplementation screen using active Mutator transposable element lines. Homozygous ig1 mutants have abnormal leaf morphology as well as abnormal embryo sac development. Affected leaves have disrupted abaxial-adaxial polarity and fail to repress the expression of meristem-specific knotted-like homeobox (knox) genes in leaf primordia, causing a proliferative, stem cell identity to persist in these cells. Despite the superficial similarity of ig1-O leaves and embryo sacs, ectopic knox gene expression cannot be detected in ig1-O embryo sacs.

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Section: Discussionmentioning

confidence: 99%

Theindeterminate gametophyte1Gene of Maize Encodes a LOB Domain Protein Required for Embryo Sac and Leaf Development

2007

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“…In order to enter the ovules for fertilization, pollen tubes respond to guidance cues that emanate from the ovule and target growth toward and into the ovule via an aperture known as the micropyle (Hulskamp et al, 1995;Higashiyama et al, 1998Higashiyama et al, , 2001Shimizu and Okada, 2000;Huck et al, 2003;Palanivelu et al, 2003;Marton et al, 2005). Pollen tubes from a number of plant species grown in vitro retain the capacity to grow toward and penetrate ovules (Higashiyama et al, 1998(Higashiyama et al, , 2001), though at efficiency substantially lower than what occurs in vivo.…”

Section: Expression Of Gfp-rab11b(dn) and Gfp-rab11b(ca) Inhibits In mentioning

confidence: 99%

Rab11 GTPase-Regulated Membrane Trafficking Is Crucial for Tip-Focused Pollen Tube Growth in Tobacco

et al. 2005

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Pollen tube growth is a polarized growth process whereby the tip-growing tubes elongate within the female reproductive tissues to deliver sperm cells to the ovules for fertilization. Efficient and regulated membrane trafficking activity incorporates membrane and deposits cell wall molecules at the tube apex and is believed to underlie rapid and focused growth at the pollen tube tip. Rab GTPases, key regulators of membrane trafficking, are candidates for important roles in regulating pollen tube growth. We show that a green fluorescent protein–tagged Nicotiana tabacum pollen-expressed Rab11b is localized predominantly to an inverted cone-shaped region in the pollen tube tip that is almost exclusively occupied by transport vesicles. Altering Rab11 activity by expressing either a constitutive active or a dominant negative variant of Rab11b in pollen resulted in reduced tube growth rate, meandering pollen tubes, and reduced male fertility. These mutant GTPases also inhibited targeting of exocytic and recycled vesicles to the pollen tube inverted cone region and compromised the delivery of secretory and cell wall proteins to the extracellular matrix. Properly regulated Rab11 GTPase activity is therefore essential for tip-focused membrane trafficking and growth at the pollen tube apex and is pivotal to reproductive success.

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“…The advent of fluorescent proteins, such as green fluorescent protein (GFP) from the jellyfish Aequorea victoria (Chalfie et al ., 1994) and its variants, has endowed researchers with powerful tools to monitor gene expression (Harper et al ., 1999;Sunilkumar et al , 2002) and gene silencing (Ruiz et al ., 1998), and to define spatial (Johnson et al ., 2005), developmental (Marton et al ., 2005) and quantitative (Tang & Newton, 2004) properties of promoters. The lack of requirement for exogenous substrate, cofactors or histochemical fixation makes GFP a particularly valuable reporter for plant cells, which are not as permeable as animal cells (Hanson & Köhler, 2001).…”

Section: Introductionmentioning

confidence: 99%

The dark side of green fluorescent protein

et al. 2005

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Summary• Here, severe interference of chlorophyll with green fluorescent protein (GFP) fluorescence is described for medicago ( Medicago truncatula ), rice ( Oryza sativa ) and arabidopsis ( Arabidopsis thaliana ). This interference disrupts the proportional relationship between GFP content and fluorescence that is intrinsic to its use as a quantitative reporter.• The involvement of chlorophyll in the loss of GFP fluorescence with leaf age was shown in vivo , by the removal of chlorophyll through etiolation or by ethanol extraction, and in vitro , by titration of a GFP solution with chlorophyll solutions of various concentrations.• A substantial decrease in fluorescence in early development of medicago and rice leaves correlated with chlorophyll accumulation. In all three species tested, removal of chlorophyll yielded up to a 10-fold increase in fluorescence. Loss of GFP fluorescence in vitro was 4-fold greater for chlorophyll b than for chlorophyll a.• Differences exist between plant species for the discrepancy between apparent GFP fluorescence and its actual level in green tissues. Substantial errors in estimating promoter activity from GFP fluorescence can occur if pigment interference is not considered.

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Micropylar Pollen Tube Guidance by Egg Apparatus 1 of Maize

Cited by 280 publications

References 13 publications

Theindeterminate gametophyte1Gene of Maize Encodes a LOB Domain Protein Required for Embryo Sac and Leaf Development

Theindeterminate gametophyte1Gene of Maize Encodes a LOB Domain Protein Required for Embryo Sac and Leaf Development

Rab11 GTPase-Regulated Membrane Trafficking Is Crucial for Tip-Focused Pollen Tube Growth in Tobacco

The dark side of green fluorescent protein

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