Molecular analysis of SCARECROW genes expressed in white lupin cluster roots

Laila Sbabou, Bruna Bucciarelli, Susan Miller, Junqi Liu, Fatiha Berhada, Abdelkarim Filali-Maltouf, Deborah Allan, Carroll Vance

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33 Scopus citations


The Scarecrow (SCR) transcription factor plays a crucial role in root cell radial patterning and is required for maintenance of the quiescent centre and differentiation of the endodermis. In response to phosphorus (P) deficiency, white lupin (Lupinus albus L.) root surface area increases some 50-fold to 70-fold due to the development of cluster (proteoid) roots. Previously it was reported that SCR-like expressed sequence tags (ESTs) were expressed during early cluster root development. Here the cloning of two white lupin SCR genes, LaSCR1 and LaSCR2, is reported. The predicted amino acid sequences of both LaSCR gene products are highly similar to AtSCR and contain C-terminal conserved GRAS family domains. LaSCR1 and LaSCR2 transcript accumulation localized to the endodermis of both normal and cluster roots as shown by in situ hybridization and gene promoter::reporter staining. Transcript analysis as evaluated by quantitative real-time-PCR (qRT-PCR) and RNA gel hybridization indicated that the two LaSCR genes are expressed predominantly in roots. Expression of LaSCR genes was not directly responsive to the P status of the plant but was a function of cluster root development. Suppression of LaSCR1 in transformed roots of lupin and Medicago via RNAi (RNA interference) delivered through Agrobacterium rhizogenes resulted in decreased root numbers, reflecting the potential role of LaSCR1 in maintaining root growth in these species. The results suggest that the functional orthologues of AtSCR have been characterized.

Original languageEnglish (US)
Pages (from-to)1351-1363
Number of pages13
JournalJournal of experimental botany
Issue number5
StatePublished - Mar 2010

Bibliographical note

Funding Information:
This work was supported by United States Department of Agriculture, National Research Initiative, CSREES Grant Number 2005-35100-16002; USDA Agricultural Research Service CRIS number 3640-21000-024-00D; the Fulbright Scholar Program; and the Moroccan–American Commission for Educational & Cultural Exchange for financial support for this work.


  • Cluster roots
  • Endodermis
  • Interfering RNA
  • Lupinus albus
  • Scarecrow
  • Short roots


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