Pleiotropic effects of the<Emphasis Type="Italic"> male sterile33</Emphasis> (<Emphasis Type="Italic">ms33</Emphasis>) mutation in<Emphasis Type="Italic">
Arabidopsis</Emphasis> are associated with modifications in endogenous gibberellins,indole-3-acetic acid and abscisic acid |
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Authors: | Houman?Fei Ruichuan?Zhang Richard?P?Pharis Email author" target="_blank">Vipen?K?SawhneyEmail author |
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Institution: | (1) Department of Biology, University of Saskatchewan, 112 Science Place , Saskatoon, SK, S7N 5E2, Canada;(2) Department of Biological Sciences, University of Calgary, Calgary, AB, T2N 1N4, Canada;(3) Present address: Plant Biotechnology Institute, 110 Gymnasium Place, Saskatoon, S7N 0W9, Canada |
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Abstract: | Earlier, we reported that mutation in the Male Sterile33 (MS33) locus in Arabidopsis thaliana causes inhibition of stamen filament growth and a defect in the maturation of pollen grains Fei and Sawhney (1999) Physiol Plant 105:165–170; Fei and Sawhney (2001) Can J Bot 79:118–129]. Here we report that the ms33 mutant has other pleiotropic effects, including aberrant growth of all floral organs and a delay in seed germination and in flowering time. These defects could be partially or completely restored by low temperature or by exogenous gibberellin A4 (GA4), which in all cases was more effective than GA3 Analysis of endogenous GAs showed that in wild type (WT) mature flowers GA4 was the major GA, and that relative to WT the ms33
flowers had low levels of the growth active GAs, GA1 and GA4, and very reduced levels of GA9, GA24 and GA15, precursors of GA4. This suggests that mutation in the MS33 gene may suppress the GA biosynthetic pathway that leads to GA4
via GA9 and the early 13-H C20
GAs. WT flowers also possessed a much higher level of indole-3-acetic acid (IAA), and a lower level of abscisic acid (ABA), relative to ms33 flowers. Low temperature induced partial restoration of male fertility in the ms33
flowers and this was associated with partial increase in GA4. In contrast, in WT flowers GA1 and GA4 were very much reduced by low temperature. Low temperature also had little effect on IAA or ABA levels of ms33 flowers, but did reduce (>2-fold) IAA levels in WT flowers. The double mutants, ms33 aba1-1 (an ABA-deficient mutant), and ms33 spy-3 (a GA signal transduction mutant) had flower phenotypes similar to ms33. Together, the data suggest that the developmental defects in the
ms33 mutant are unrelated to ABA levels, but may be causally associated with reduced levels of IAA, GA1 and GA4, compared to WT flowers.Abbreviations ABA
Abscisic acid
- GA
Gibberellin
- GC-MS-SIM
Gas chromatography-mass spectrometry-selected ion monitoring
- IAA
Indole-3-acetic acid
- ms33
Male sterile33
mutant
- PP333
Paclobutrazol
- WT
Wild type |
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Keywords: | Arabidopsis Gibberellin Indole-3-acetic acid Male sterility ms33 mutant Pleiotropy |
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