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The regulation of endosperm development by auxin in maize (Zea mays L.).

Record Type:	Electronic resources : Monograph/item
Title/Author:	The regulation of endosperm development by auxin in maize (Zea mays L.)./
Author:	Lur, Huu-Sheng.
Published:	Ann Arbor : ProQuest Dissertations & Theses, : 1990,
Description:	129 p.
Notes:	Source: Dissertations Abstracts International, Volume: 52-01, Section: B.
Contained By:	Dissertations Abstracts International52-01B.
Subject:	Agronomy. -
Online resource:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=9027140
ISBN:	9798206886627

The regulation of endosperm development by auxin in maize (Zea mays L.).
Lur, Huu-Sheng.

The regulation of endosperm development by auxin in maize (Zea mays L.). - Ann Arbor : ProQuest Dissertations & Theses, 1990 - 129 p.

Source: Dissertations Abstracts International, Volume: 52-01, Section: B.

Thesis (Ph.D.)--Cornell University, 1990.

This item must not be sold to any third party vendors.

To advance our understanding of the roles of auxin and cytokinin in developing maize endosperm, defective kernel mutants (dek) and the effects of exogenously applied synthetic hormone analogues were studied. Developmental processes involved in establishing endosperm growth potential were examined, including cell division, nuclear DNA endoreduplication and zein accumulation in maize endosperms. In a time-course study, high concentrations of the cytokinins, zeatin and zeatin riboside (ZR), in endosperm were associated with the rapid increase of endosperm cell number. Increase of the auxin, indole-3-acetic acid (IAA), was temporally associated with the start of rapid fresh weight accumulation, enlargement of nuclei diameter and increase in nuclear DNA content. In studies of 18 dek mutants and their corresponding wild types, several mutants had auxin and cytokinin concentrations that significantly differed from their wild type counterparts. The mutant, dek18, had extremely low IAA concentration and was the only mutant in which kernel growth was partially restored by exogenously applied auxin. In comparisons of low-IAA mutants with their corresponding wild types and tests of auxin application on dek18, auxin enhanced endosperm nuclear size and expression of zein protein, but did not consistently affect endosperm cell division. In studies using synthetic growth regulator applications, the antiauxin, p-chlorophenoxyisobutyric acid, inhibited the increase of endosperm fresh weight and nuclei DNA content. When the auxin, 2,4-dichlorophenoxyacetic acid (2,4D), was applied on normal kernels, kernel fresh weight and post-mitotic nuclear DNA content was significantly enhanced, and nuclear size were also significantly increased. Auxin (2,4D) enhanced the expression of zein mRNA, and the synthesis of zein polypeptides, especially the polypeptides in the size classes 22, 19, 15 and 11 kDa. The 11 kDa polypeptide, whose accumulation in control endosperm was first observed at 11 DAP, was induced as early as 7 DAP in 2,4D-treated endosperms. I conclude that auxin may play a role in regulating the transition (differentiation) of endosperm cells from the processes of cell division to reserve synthesis.

ISBN: 9798206886627Subjects--Topical Terms:

2122783
Agronomy.

The regulation of endosperm development by auxin in maize (Zea mays L.).
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245 1 4 $a The regulation of endosperm development by auxin in maize (Zea mays L.).
260 1 $a Ann Arbor : $b ProQuest Dissertations & Theses, $c 1990
300 $a 129 p.
500 $a Source: Dissertations Abstracts International, Volume: 52-01, Section: B.
500 $a Publisher info.: Dissertation/Thesis.
502 $a Thesis (Ph.D.)--Cornell University, 1990.
506 $a This item must not be sold to any third party vendors.
506 $a This item must not be added to any third party search indexes.
520 $a To advance our understanding of the roles of auxin and cytokinin in developing maize endosperm, defective kernel mutants (dek) and the effects of exogenously applied synthetic hormone analogues were studied. Developmental processes involved in establishing endosperm growth potential were examined, including cell division, nuclear DNA endoreduplication and zein accumulation in maize endosperms. In a time-course study, high concentrations of the cytokinins, zeatin and zeatin riboside (ZR), in endosperm were associated with the rapid increase of endosperm cell number. Increase of the auxin, indole-3-acetic acid (IAA), was temporally associated with the start of rapid fresh weight accumulation, enlargement of nuclei diameter and increase in nuclear DNA content. In studies of 18 dek mutants and their corresponding wild types, several mutants had auxin and cytokinin concentrations that significantly differed from their wild type counterparts. The mutant, dek18, had extremely low IAA concentration and was the only mutant in which kernel growth was partially restored by exogenously applied auxin. In comparisons of low-IAA mutants with their corresponding wild types and tests of auxin application on dek18, auxin enhanced endosperm nuclear size and expression of zein protein, but did not consistently affect endosperm cell division. In studies using synthetic growth regulator applications, the antiauxin, p-chlorophenoxyisobutyric acid, inhibited the increase of endosperm fresh weight and nuclei DNA content. When the auxin, 2,4-dichlorophenoxyacetic acid (2,4D), was applied on normal kernels, kernel fresh weight and post-mitotic nuclear DNA content was significantly enhanced, and nuclear size were also significantly increased. Auxin (2,4D) enhanced the expression of zein mRNA, and the synthesis of zein polypeptides, especially the polypeptides in the size classes 22, 19, 15 and 11 kDa. The 11 kDa polypeptide, whose accumulation in control endosperm was first observed at 11 DAP, was induced as early as 7 DAP in 2,4D-treated endosperms. I conclude that auxin may play a role in regulating the transition (differentiation) of endosperm cells from the processes of cell division to reserve synthesis.
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650 4 $a Botany. $3 516217
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793 $a English
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