The grapevine transcription factor WRKY2 influences the lignin pathway and xylem development in tobacco.
Previous work has shown that transgenic tobacco plants constitutively over-expressing the Vitis vinifera L. transcription factor VvWRKY2 exhibit reduced susceptibility to necrotrophic fungal pathogens, suggesting that this transcription factor plays a role in grapevine response to phytopathogens. The work presented here characterizes the modifications in cell wall structure observed in the stems and petioles of these transgenic plants. Histochemical stainings of stem and petiole cross-sections using phloroglucinol or Maüle reagents revealed a delay in xylem formation, particularly in the petioles, and differences in lignin composition. Evaluation of lignin quantity and quality showed a decrease in the syringyl/guaiacyl ratio in both stem and petioles. Expression analysis using RT-PCR and potato microarrays showed that tobacco plants over-expressing VvWRKY2 exhibited altered expression of genes involved in lignin biosynthesis pathway and cell wall formation. The ability of VvWRKY2 to activate the promoter of the VvC4H gene, which is involved in the lignin biosynthetic pathway, was confirmed by transient transcriptional activation assays in tobacco protoplasts. Moreover, in situ hybridization revealed that VvWRKY2 is specifically expressed in cells undergoing lignification in young grapevine stems. Together, these results confirm that VvWRKY2 plays a role in regulating lignification in grapevine, possibly in response to biotic or abiotic stresses.
Guillaumie
Sabine
S
UMR 1287 Ecophysiologie et Génomique, Université de Bordeaux, INRA, Institut des Sciences de la Vigne et du Vin, 210 Chemin de Leysotte, 33882, Villenave d'Ornon, France.
Mzid
Rim
R
Méchin
Valérie
V
Léon
Céline
C
Hichri
Imène
I
Destrac-Irvine
Agnès
A
Trossat-Magnin
Claudine
C
Delrot
Serge
S
Lauvergeat
Virginie
V
D017403:In Situ Hybridization; D008031:Lignin / Q000096:biosynthesis*; D020411:Oligonucleotide Array Sequence Analysis; D010940:Plant Proteins / Q000235:genetics / Q000502:physiology*; D030821:Plants, Genetically Modified / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014026:Nicotiana / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism*; D014157:Transcription Factors / Q000235:genetics / Q000502:physiology*; D027843:Vitis / Q000235:genetics*; D052584:Xylem / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism
D010940:Plant Proteins; D014157:Transcription Factors; D008031:Lignin