|
Plant Cell, Vol. 12, 1455-1466, August 2000, Copyright © 2000, American Society of Plant Physiologists
Expansin Message Regulation in Parasitic Angiosperms: Marking Time in Development
Ronan C. O'Malleya and
David G. Lynna
a Searle and Jones Chemistry Laboratories, University of Chicago, 5735 Ellis Avenue, Chicago, Illinois 60637
Correspondence to:
David G. Lynn, Current address: Departments of Chemistry and Biology, Emerson Hall, Emory University, Atlanta, GA 30322., dlynn2{at}emory.edu (E-mail), 404-727-6586 (fax)
Parasitic strategies are widely distributed across the angiosperms and are estimated to have evolved at least eight different times. Within the obligate hemiparasitic and holoparasitic members, elaborate strategies for host selection have emerged. Here, we demonstrate that in the parasitic Scrophulariceae Striga asiatica, for which signal-mediated host detection is critical, expansin mRNA provides a reliable and accurate downstream molecular marker for the transition to the parasitic mode. Three different expansin genes, saExp1, saExp2, and saExp3, are regulated by xenognostic quinones. saExp3 appears to function as a seedling expansin, and its mRNA is depleted within minutes after induction of the host attachment organ. saExp1 and saExp2 share less homology with the known expansins, and their transcripts accumulate linearly over a critical induction period. The regulation of these genes suggests that the resources for developmental commitment must accumulate to a defined threshold before commitment to organogenesis is terminal. When the induction signal is removed prematurely, the accumulated message decays with a time constant that correlates with the time required for additional signal exposures to reinduce parasitic development. These results suggest that sophisticated controls exist for the accumulation of the necessary components for terminal commitment to the parasitic mode. Furthermore, building on the redox dependence of the inducing signal, they suggest a model akin to a "molecular capacitor" for clocking organogenesis in S. asiatica.
This article has been cited by other articles:

|
 |

|
 |
 
M. Alkio, T. M. Tabuchi, X. Wang, and A. Colon-Carmona
Stress responses to polycyclic aromatic hydrocarbons in Arabidopsis include growth inhibition and hypersensitive response-like symptoms
J. Exp. Bot.,
November 1, 2005;
56(421):
2983 - 2994.
[Abstract]
[Full Text]
[PDF]
|
 |
|

|
 |

|
 |
 
P. J. Rich, C. Grenier, and G. Ejeta
Striga Resistance in the Wild Relatives of Sorghum
Crop Sci.,
November 1, 2004;
44(6):
2221 - 2229.
[Abstract]
[Full Text]
[PDF]
|
 |
|

|
 |

|
 |
 
D. J. Cosgrove, L. C. Li, H.-T. Cho, S. Hoffmann-Benning, R. C. Moore, and D. Blecker
The Growing World of Expansins
Plant Cell Physiol.,
December 15, 2002;
43(12):
1436 - 1444.
[Abstract]
[Full Text]
[PDF]
|
 |
|

|
 |

|
 |
 
W. J. Keyes, J. V. Taylor, R. P. Apkarian, and D. G. Lynn
Dancing Together. Social Controls in Parasitic Plant Development
Plant Physiology,
December 1, 2001;
127(4):
1508 - 1512.
[Full Text]
[PDF]
|
 |
|

|
 |

|
 |
 
M. Matvienko, M. J. Torres, and J. I. Yoder
Transcriptional Responses in the Hemiparasitic Plant Triphysaria versicolor to Host Plant Signals
Plant Physiology,
September 1, 2001;
127(1):
272 - 282.
[Abstract]
[Full Text]
[PDF]
|
 |
|
|
|