| Abstract Detail
Lipids Ishiguro, Mai [1], Kenta, Hosokawa [2], Masahiro, Nishikawa [2], Imai, Hiroyuki [2]. Characterization of sphingoid base-1-phosphate lyase in Arabidopsis thaliana. Sphingoid base 1-phosphates are resolved into ethanolamine-phosphate and C16-fatty aldehyde catalyzed by sphingosine phosphate lyase (SPL). In this study, to assess the functional consequence of the loss of function of AtSPL1, we characterized two independent Arabidopsis mutants (atspl1-1 and atspl1-2) with T-DNA insertions in the AtSPL1 gene. A sphingolipid metabolite sphingosine 1-phosphate (S1P) is a signaling molecule involved in abscisic acid (ABA) regulation of guard cell turgor (Nature 410: 596-599, 2001; Nature 423: 651-654, 2003). Several lines of evidence suggest that sphingosine kinase plays an important role in ABA signaling in stomatal switching, whereas the cellular levels of S1P may be controlled by the relative enzymatic activities involved in the synthesis and breakdown of S1P. Interestingly, we previously have found that transcripts of a sphingosine kinase gene, AtLCBK1, were slightly increased by low humidity stress, whereas AtSPL1 transcripts were decreased. Thus to evaluate mechanisms of the S1P signaling linking ABA to regulate stomatal aperture, functional characterization of several enzymes that control the cellular levels of S1P is very important. Using isolated epidermal peels, we observed that stomatal closing in the two AtSPL1 mutant lines was more sensitive to ABA than in the wild type. In addition, the rate of transpiration in excised leaves was greater in wild-type than in mutant plants. These results suggest that AtSPL1 also plays an important role in ABA-induced stomatal aperture and dehydration stress signaling.
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1 - Konan University, Department of Biology, 8-9-1 Okamoto, Higashinada-ku, Kobe, 658-8501, Japan
2 - Konan University, Department of Biology
Keywords:
sphingolipid
sphingosine-1-phosphate
ABA
drought stress.
Presentation Type: Plant Biology Abstract
Session: P
Location: Exhibit Hall (Northeast, Southwest & Southeast)/Hilton
Date: Sunday, July 8th, 2007
Time: 8:00 AM
Number: P21004
Abstract ID:2542 |
