The Maize Aberrant Pollen Transmission 1 Gene Is a SABRE/KIP Homolog Required for Pollen Tube Growth

By Xu, Zhennan; Dooner, Hugo K. | Genetics, February 2006 | Go to article overview

The Maize Aberrant Pollen Transmission 1 Gene Is a SABRE/KIP Homolog Required for Pollen Tube Growth


Xu, Zhennan, Dooner, Hugo K., Genetics


ABSTRACT

Maize (Zea mays) pollen tubes grow in the styles at a rate of >1 µm/sec. We describe here a gene required to attain that striking rate. The aberrant pollen transmission 1 (apt1) gene of maize was identified by an Ac-tagged mutation that displayed a severe pollen transmission deficit in heterozygotes. Rare apt1 homozygotes can be recovered, aided by phenotypic selection for Ac homozygotes. Half of the pollen in heterozygotes and most of the pollen in homozygotes germinate short and twisted pollen tubes. The apt1 gene is 26 kb long, makes an 8.6-kb pollen-specific transcript spliced from 22 exons, and encodes a protein of 2607 amino acids. The APT1 protein is homologous to SABRE and KIP, Arabidopsis proteins of unknown function involved in the elongation of root cortex cells and pollen tubes, respectively. Subcellular localization analysis demonstrates that APT1 colocalizes with a Golgi protein marker in growing tobacco pollen tubes. We hypothesize that the APT1 protein is involved in membrane trafficking and is required for the high secretory demands of tip growth in pollen tubes. The apt1-m1(Ac) mutable allele is an excellent tool for selecting Ac transpositions because of the strong negative selection pressure operating against the parental Ac site.

IN higher plants, pollination is initiated with the transfer of pollen from the anther to the stigma. Once recognized by the stigma, the pollen hydrates and germinates a pollen tube. The pollen tube elongates along the transmitting tract in the style and delivers its two sperm cells to the female gametophyte to undergo double fertilization (McCoRMiCK 2004). Elongation of the pollen tube can be over a distance of a few hundred micrometers to several centimeters and constitutes the most rapid growth of any cell known (HEPLER et al. 2001). This elongation is particularly remarkable in the polystigmatic styles of maize (Zea mays), where the pollen tube grows at the astounding rate of 1 cm/hr (BEDINGER 1992). Evidence from a large collection of maize aneuploid stocks, in which development of the deficient microspores was slowed down or arrested, suggests that genes required for pollen development are expressed gametophytically and dispersed throughout the genome (KINDIGER et al. 1991). By implication, mutations that affect male gametophytic development will be recovered rarely through the pollen. They can, however, be identified by the aberrant segregation of linked markers.

Several molecules that control pollen germination and the elongation and guidance of pollen tubes have been identified recently. Lipophilic molecules in the exine wall of the pollen (LORD 2000; LORD and RUSSELL 2002), lipids (PREUSS et al. 1993; HULSKAMP et al. 1995a), pollen-coat proteins (MAYFIELD and PREUSS 2000; MAYFIELD et al. 2001), and a calmodulin-binding protein (GoLOVKiN and REDDY 2003) play important roles in pollen germination. Extracellular cues in the pistil and proteins produced by the embryo sac are likely involved in guiding the pollen tube toward the ovules and female gametophytes (CHEUNG et al. 1995; HULSKAMP et al. 1995b; RAY et al. 1997; SHIMIZU and OKADA 2000; HUCK et al. 2003; MARTON et al. 2005). Even the arrest of pollen tube growth by the embryo sac is under genetic control, as demonstrated by the feronia mutation in Arabidopsis, in which synergid degeneration fails to occur and pollen tubes continue to grow, leading to impaired fertility (HucK et al. 2003).

Substantial molecular, genetic, and cellular biological data have clearly demonstrated that pollen tube growth is tightly regulated by a Ca2+ gradient (PiERSON et al. 1994; HOLDAWAY-CLARKE et al. 1997), a K+ channel of the Shaker family (MOULINE et al. 2002), a Ca2+dependent protein kinase (EsTRUCH et al. 1994; MOUTINHO et al. 1998), an intact actin cytoskeleton (CHEN et al. 2002, 2003), F-actin level (Fu et al. 2001), Rop GTPase (Li et al. 1999; ARTHUR et al. 2003), and Rab GTPase (CHEUNG et al. …

The rest of this article is only available to active members of Questia

Already a member? Log in now.

Notes for this article

Add a new note
If you are trying to select text to create highlights or citations, remember that you must now click or tap on the first word, and then click or tap on the last word.
One moment ...
Default project is now your active project.
Project items
Notes
Cite this article

Cited article

Style
Citations are available only to our active members.
Buy instant access to cite pages or passages in MLA 8, MLA 7, APA and Chicago citation styles.

(Einhorn, 1992, p. 25)

(Einhorn 25)

(Einhorn 25)

1. Lois J. Einhorn, Abraham Lincoln, the Orator: Penetrating the Lincoln Legend (Westport, CT: Greenwood Press, 1992), 25, http://www.questia.com/read/27419298.

Note: primary sources have slightly different requirements for citation. Please see these guidelines for more information.

Cited article

The Maize Aberrant Pollen Transmission 1 Gene Is a SABRE/KIP Homolog Required for Pollen Tube Growth
Settings

Settings

Typeface
Text size Smaller Larger Reset View mode
Search within

Search within this article

Look up

Look up a word

  • Dictionary
  • Thesaurus
Please submit a word or phrase above.
Print this page

Print this page

Why can't I print more than one page at a time?

Help
Full screen
Items saved from this article
  • Highlights & Notes
  • Citations
Some of your highlights are legacy items.

Highlights saved before July 30, 2012 will not be displayed on their respective source pages.

You can easily re-create the highlights by opening the book page or article, selecting the text, and clicking “Highlight.”

matching results for page

    Questia reader help

    How to highlight and cite specific passages

    1. Click or tap the first word you want to select.
    2. Click or tap the last word you want to select, and you’ll see everything in between get selected.
    3. You’ll then get a menu of options like creating a highlight or a citation from that passage of text.

    OK, got it!

    Cited passage

    Style
    Citations are available only to our active members.
    Buy instant access to cite pages or passages in MLA 8, MLA 7, APA and Chicago citation styles.

    "Portraying himself as an honest, ordinary person helped Lincoln identify with his audiences." (Einhorn, 1992, p. 25).

    "Portraying himself as an honest, ordinary person helped Lincoln identify with his audiences." (Einhorn 25)

    "Portraying himself as an honest, ordinary person helped Lincoln identify with his audiences." (Einhorn 25)

    "Portraying himself as an honest, ordinary person helped Lincoln identify with his audiences."1

    1. Lois J. Einhorn, Abraham Lincoln, the Orator: Penetrating the Lincoln Legend (Westport, CT: Greenwood Press, 1992), 25, http://www.questia.com/read/27419298.

    Cited passage

    Thanks for trying Questia!

    Please continue trying out our research tools, but please note, full functionality is available only to our active members.

    Your work will be lost once you leave this Web page.

    Buy instant access to save your work.

    Already a member? Log in now.

    Search by... Author
    Show... All Results Primary Sources Peer-reviewed

    Oops!

    An unknown error has occurred. Please click the button below to reload the page. If the problem persists, please try again in a little while.