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Expansin message regulation in parasitic angiosperms: marking time in development
1Searle and Jones Chemistry Laboratories, University of Chicago, 5735 Ellis Avenue, Chicago, Illinois 60637, USA.
The Plant Cell
|August 19, 2000
Summary
Parasitic plant Striga asiatica uses expansin gene expression to time its transition to parasitism. This molecular marker, regulated by host signals, ensures commitment to organogenesis.
Area of Science:
- Plant biology
- Evolutionary biology
- Molecular genetics
Background:
- Parasitic plants exhibit diverse host-selection strategies.
- Striga asiatica, a parasitic angiosperm, relies on signal-mediated host detection.
- Expansin genes are involved in plant development and cell wall modification.
Purpose of the Study:
- To identify molecular markers for the transition to parasitism in Striga asiatica.
- To investigate the role of expansin genes in host detection and parasitic development.
- To elucidate the regulatory mechanisms controlling organogenesis in parasitic plants.
Main Methods:
- Quantitative analysis of expansin mRNA levels (saExp1, saExp2, saExp3) in Striga asiatica.
- Investigating the regulation of expansin genes by xenognostic quinones.
- Assessing the impact of signal removal on mRNA accumulation and parasitic development.
Main Results:
- Three expansin genes (saExp1, saExp2, saExp3) are regulated by xenognostic quinones.
- saExp3 mRNA is rapidly depleted upon host attachment organ induction.
- saExp1 and saExp2 transcripts accumulate linearly, suggesting a threshold-dependent commitment.
- mRNA decay rates correlate with reinduction times, indicating sophisticated regulatory controls.
Conclusions:
- Expansin mRNA serves as a reliable molecular marker for parasitic transition in Striga asiatica.
- A 'molecular capacitor' model is proposed for timing organogenesis based on signal-dependent mRNA accumulation.
- These findings reveal intricate controls governing developmental commitment in parasitic plants.
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