Analysis of vascular development in the hydra sterol biosynthetic mutants of Arabidopsis.
BACKGROUND
The control of vascular tissue development in plants is influenced by diverse hormonal signals, but their interactions during this process are not well understood. Wild-type sterol profiles are essential for growth, tissue patterning and signalling processes in plant development, and are required for regulated vascular patterning.


RESULTS
Here we investigate the roles of sterols in vascular tissue development, through an analysis of the Arabidopsis mutants hydra1 and fackel/hydra2, which are defective in the enzymes sterol isomerase and sterol C-14 reductase respectively. We show that defective vascular patterning in the shoot is associated with ectopic cell divisions. Expression of the auxin-regulated AtHB8 homeobox gene is disrupted in mutant embryos and seedlings, associated with variably incomplete vascular strand formation and duplication of the longitudinal axis. Misexpression of the auxin reporter proIAA2ratioGUS and mislocalization of PIN proteins occurs in the mutants. Introduction of the ethylene-insensitive ein2 mutation partially rescues defective cell division, localization of PIN proteins, and vascular strand development.


CONCLUSIONS
The results support a model in which sterols are required for correct auxin and ethylene crosstalk to regulate PIN localization, auxin distribution and AtHB8 expression, necessary for correct vascular development.
Pullen
Margaret
M
The Integrative Cell Biology Laboratory, School of Biological and Biomedical Sciences, Durham University, Durham, United Kingdom.
Clark
Nick
N
Zarinkamar
Fatemeh
F
Topping
Jennifer
J
Lindsey
Keith
K
D017360:Arabidopsis / Q000166:cytology / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics; D001692:Biological Transport; D002455:Cell Division; D005030:Ethylenes / Q000378:metabolism; D018506:Gene Expression Regulation, Plant; D007210:Indoleacetic Acids / Q000378:metabolism; D009154:Mutation; D010641:Phenotype; D013261:Sterols / Q000096:biosynthesis*
D029681:Arabidopsis Proteins; D005030:Ethylenes; D007210:Indoleacetic Acids; D013261:Sterols; C036216:ethylene
Plant Cell. 2006 Nov;18(11):3058-72
17138700
Mol Syst Biol. 2010 Jun 8;6:373
20531403
Bioessays. 1996 Aug;18(8):647-54
8760338
Plant Cell. 2004 Jul;16(7):1730-40
15194817
Plant Cell. 2003 Mar;15(3):612-25
12615936
Curr Biol. 2003 Aug 19;13(16):1378-87
12932321
Dev Biol. 1999 Nov 15;215(2):407-19
10545247
Nature. 2001 Jun 7;411(6838):709-13
11395776
Plant Physiol. 2010 Jun;153(2):741-56
20421456
Science. 2007 Jul 27;317(5837):507-10
17656722
Curr Biol. 2000 Aug 24;10(16):R601-4
10985378
Plant Cell. 2009 Feb;21(2):568-80
19218398
Development. 1999 Jul;126(13):2979-91
10357941
Planta. 2004 Sep;219(5):773-83
15138822
Trends Plant Sci. 2003 Nov;8(11):521-5
14607096
Development. 1997 Nov;124(21):4415-24
9334289
Planta. 1996;200(2):229-37
8904808
J Mol Biol. 1995 Aug 25;251(4):533-49
7658471
Plant Cell. 2007 Jul;19(7):2169-85
17630276
Development. 2000 Aug;127(15):3197-204
10887076
Plant Cell. 2002 May;14(5):1017-31
12034894
Science. 2002 Jan 4;295(5552):147-50
11778054
Plant Cell. 1999 Nov;11(11):2123-37
10559439
Cell. 1997 Sep 5;90(5):929-38
9298904
Nat Cell Biol. 2009 Jun;11(6):731-8
19448626
Genes Dev. 2001 Oct 15;15(20):2648-53
11641271
Plant Cell. 1990 Jun;2(6):513-23
2152173
Plant Cell. 2005 Jan;17(1):61-76
15598805
Development. 2004 Nov;131(21):5341-51
15486337
Nat Cell Biol. 2008 Feb;10(2):237-44
18223643
Genes Dev. 2000 Jun 15;14(12):1471-84
10859166
Plant Physiol. 2004 Apr;134(4):1614-23
15047904
Plant Cell Physiol. 2000 Jun;41(6):649-56
10945333
Development. 1995 Dec;121(12):4171-82
8575317
Cell. 1999 Nov 24;99(5):463-72
10589675
Plant Physiol. 2007 Feb;143(2):924-40
17189330
Genes Dev. 2000 Jun 15;14(12):1485-97
10859167
Genes Dev. 2006 Oct 15;20(20):2902-11
17043314
Plant Cell. 1991 Jul;3(7):677-684
12324609
Nature. 2001 Mar 15;410(6826):380-3
11268216
EMBO J. 1998 Mar 2;17(5):1405-11
9482737
Plant Physiol. 2001 Jun;126(2):643-55
11402194
Development. 2004 Mar;131(5):1089-100
14973283
Plant Cell. 2002 Sep;14(9):2045-58
12215504
Cell. 2002 Mar 8;108(5):661-73
11893337
Genes Dev. 2006 Apr 15;20(8):1015-27
16618807
Plant Cell. 2007 Jul;19(7):2197-212
17630274
Cell. 2004 Oct 1;119(1):109-20
15454085
Plant Cell. 2007 Jul;19(7):2186-96
17630275
Trends Plant Sci. 2005 Apr;10(4):170-7
15817418
Development. 2009 Oct;136(19):3235-46
19710171
J Exp Bot. 2008;59(1):85-92
17905731
Science. 1998 Dec 18;282(5397):2226-30
9856939
Plant J. 2004 Apr;38(2):227-43
15078327
Development. 2004 Jul;131(14):3445-55
15226260
Plant J. 2002 Jul;31(1):61-73
12100483
Curr Opin Genet Dev. 2007 Aug;17(4):337-43
17627808
Plant J. 2008 Oct;56(2):251-263
18643975