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Expression of the Tobacco Ext 1.4 Extensin Gene Upon Mechanical Constraint and Localization of Regulatory Regions
Author(s) -
Salvá I.,
Jamet É.
Publication year - 2001
Publication title -
plant biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.871
H-Index - 87
eISSN - 1438-8677
pISSN - 1435-8603
DOI - 10.1055/s-2001-11746
Subject(s) - biology , nicotiana tabacum , gene , microbiology and biotechnology , hypocotyl , gene expression , chimeric gene , regulation of gene expression , botany , genetics
Abstract: The regulation of the Ext 1.4 gene encoding a tobacco ( Nicotiana tabacum L.) extensin was studied in response to mechanical constraints. Transgenic plants carrying chimeric Ext 1.4 promoter/GUS (β‐glucuronidase)/ nos terminator or Ext 1.4 3′‐end constructs were obtained. Expression of gene fusions was found in tissues where mechanical stresses occur, e.g., during germination, as well as in root and stem tissues. Chimeric genes were successively and transiently expressed in different tissues during germination, i.e., at the tip of the root and then in the hypocotyl, during their growth through the seed coat. Moreover, they were expressed in cortical cells surrounding the emergence of adventitious and lateral roots and developmentally‐regulated in nodes. The expression of Ext 1.4 could be induced by imposing mechanical constraints due to curving of either the stems or roots. Expression then occurred in cells where it does not normally occur, i.e., in cortical cells of internodes and in the distal piliferous zone of roots. Accumulation of RNAs occurs several days after the start of the constraint. Promoter regions involved in regulation of expression of Ext 1.4 in stems, roots, and in seedlings upon mechanical constraint could be localized. Moreover, the 3′ non‐coding region was shown to modulate expression in roots. These results suggest that the regulation of Ext 1.4 following mechanical stress is dependent on both tissue‐specific and mechanical‐responsive elements.