JXB Advance Access originally published online on June 7, 2007
Journal of Experimental Botany 2007 58(10):2441-2449; doi:10.1093/jxb/erm077
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© 2007 The Author(s).
This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/2.0/uk/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.
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RESEARCH PAPER |
Decreased panicle-derived indole-3-acetic acid reduces gibberellin A1 level in the uppermost internode, causing panicle enclosure in male sterile rice Zhenshan 97A
1College of Life Sciences, Nanjing Agricultural University, Nanjing 210095, China
2LT Biosyn, Inc., Pomona, CA 91768, USA
* To whom correspondence should be addressed. E-mail: zhish{at}njau.edu.cn
Cytoplasmic male sterile (CMS) rice Zhenshan 97A (ZS97A) has been widely used in hybrid rice production in China. However, ZS97A suffers from serious panicle enclosure, which blocks normal pollination and greatly reduces seed production of hybrid rice. Little is known about the cause of panicle closure in ZS97A. In this study, it was found that the occurrence of cytoplasmic male sterility caused a deficiency of indole-3-acetic acid (IAA) in ZS97A panicles, and less IAA was provided to the uppermost internode (UI). Further, it was found that the decreased panicle-derived IAA caused a gibberellin A1 (GA1) deficiency in the UI by the down-regulation of OsGA3ox2 transcript level. Reduced GA1 level in the UI led to decreases of both cell number and cell elongation, resulting in a shortened UI. The shortened UI was unable to push the panicle out of the flag leaf sheath that remained normal, which resulted in panicle enclosure in ZS97A. These findings suggest that decreased panicle-derived IAA reduces the GA1 level in the UI, causing panicle enclosure in CMS rice ZS97A.
Key words: Cytoplasmic male sterility, gibberellin A1, indole-3-acetic acid, panicle enclosure, rice, uppermost internode
Received 1 December 2006; Revised 15 March 2007 Accepted 19 March 2007