Functional analysis of the durum wheat gene TdPIP2;1 and its promoter region in response to abiotic stress in rice.
In a previous work, we demonstrated that expression of TdPIP2;1 in Xenopus oocytes resulted in an increase in Pf compared to water injected oocytes. Phenotypic analyses of transgenic tobacco plants expressing TdPIP2;1 generated a tolerance phenotype towards drought and salinity stresses. To elucidate its stress tolerance mechanism at the transcriptional level, we isolated and characterized the promoter region of the TdPIP2;1 gene. A 1060-bp genomic fragment upstream of the TdPIP2;1 translated sequence has been isolated, cloned, and designated as the proTdPIP2;1 promoter. Sequence analysis of proTdPIP2;1 revealed the presence of cis regulatory elements which could be required for abiotic stress responsiveness, for tissue-specific and vascular expression. The proTdPIP2;1 promoter was fused to the β-glucuronidase (gusA) gene and the resulting construct was transferred into rice (cv. Nipponbare). Histochemical analysis of proTdPIP2;1::Gus in rice plants revealed that the GUS activity was observed in leaves, stems and roots of stably transformed rice T3 plants. Histological sections prepared revealed accumulation of GUS products in phloem, xylem and in some cells adjacent to xylem. The transcripts were up-regulated by dehydration. Transgenic rice plants overexpressing proTdPIP2;1 in fusion with TdPIP2;1, showed enhanced drought tolerance, while wild type plants were more sensitive and exhibited symptoms of wilting and chlorosis. These findings suggest that expression of the TdPIP2;1 gene regulated by its own promoter achieves enhanced drought tolerance in rice.
Plant Protection and Improvement Laboratory, Centre of Biotechnology of Sfax (CBS), University of Sfax, Route Sidi Mansour Km 6, B.P "1177", 3018 Sfax, Tunisia.
Malika
M
Ayadi
CIRAD, UMR AGAP, F-34398 Montpellier, France.
Delphine
D
Mieulet
CIRAD, UMR AGAP, F-34398 Montpellier, France.
Denis
D
Fabre
CIRAD, UMR AGAP, F-34398 Montpellier, France.
Jean-Luc
JL
Verdeil
CIRAD, UMR AGAP, F-34398 Montpellier, France.
Aurore
A
Vernet
CIRAD, UMR AGAP, F-34398 Montpellier, France.
Emmanuel
E
Guiderdoni
Plant Protection and Improvement Laboratory, Centre of Biotechnology of Sfax (CBS), University of Sfax, Route Sidi Mansour Km 6, B.P "1177", 3018 Sfax, Tunisia; ICBA, P.O. Box 14660, Dubai, United Arab Emirates. Electronic address: k.masmoudi@biosaline.org.ae.
Khaled
K
Masmoudi
D055864:Droughts; D018506:Gene Expression Regulation, Plant; D012275:Oryza / Q000235:genetics / Q000378:metabolism*; D030821:Plants, Genetically Modified; D011401:Promoter Regions, Genetic / Q000235:genetics*; D014908:Triticum / Q000235:genetics*
Abiotic stresses; TdPIP2;1 promoter; Tissular localization; Transgenic rice; Transpiration