Open AccessInduction of the Hahsp17.7G4 Promoter by Root-Knot Nematodes: Involvement of Heat-Shock Elements in Promoter Activity in Giant Cells
Author(s) -
Carolina Escobar,
Marta Barcala,
Mary Portillo,
Concepción Almoguera,
Juan Jordano,
Carmen Fenoll
Publication year - 2003
Publication title -
molecular plant-microbe interactions
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.565
H-Index - 153
eISSN - 1943-7706
pISSN - 0894-0282
DOI - 10.1094/mpmi.2003.16.12.1062
Subject(s) - biology , meloidogyne incognita , promoter , gene , reporter gene , microbiology and biotechnology , heat shock , root knot nematode , transcription (linguistics) , gene expression , nematode , heat shock factor , heat shock protein , genetics , hsp70 , ecology , linguistics , philosophy
Root-knot nematodes feed from specialized giant cells induced in the plants that they parasitize. We found that the promoter of the Hahsp17.7G4 gene, which encodes a small heat-shock protein involved in embryogenesis and stress responses, directed GUS expression in tobacco galls induced by the root-knot nematode Meloidogyne incognita. In roots containing a GUS reporter fusion to the Hahsp17.7G4 promoter, 10% of the galls stained for GUS expression 1 to 3 days after infection and the fraction stained increased to 60 to 80% 17 to 20 days after infection. A DNA fragment from -83 to +163, which contains heat-shock element (HSE) core sequences, is sufficient to support a promoter activity largely restricted to giant cells within the galls. Two-point mutations in HSE cores, previously reported to abolish the heat-shock response and to strongly reduce the embryogenesis response of the same promoter, did not reduce expression in giant cells. This suggests a distinct regulation of the promoter by nematodes. However, additional point mutations located at positions crucial for binding of heat-shock transcription factors (HSFs) caused a severe decrease in the nematode response. These results demonstrate that HSEs are involved in the promoter activation in giant cells and suggest that HSFs may mediate this response.