Loss of ovule identity induced by overexpression of the fertilization-related kinase 2 (ScFRK2), a MAPKKK from Solanum chacoense.
In order to gain information about protein kinases acting during plant fertilization and embryogenesis, a reverse genetic approach was used to determine the role of protein kinases expressed in reproductive tissues. Two cDNA clones named ScFRK1 and ScFRK2 (Solanum chacoense fertilization-related kinase 1 and 2) were isolated from an expressed sequence tag (EST) library normalized for weakly expressed genes in fertilized ovaries. These showed significant sequence similarities to members of the mitogen-activated protein kinase kinase kinase (MAPKKK) family. RNA gel blot and RNA in situ hybridization analyses confirmed the strong up-regulation of ScFRK2 in ovules after fertilization. In addition, ScFRK2 mRNAs accumulate during early ovule development in the megasporocyte and in the integument of developing ovules. Overexpression of ScFRK2 led to the production of fruits with a severely reduced number of seeds. The seeds that were produced also exhibited developmental retardation. Analysis of ovaries prior to fertilization showed that the seedless phenotype was caused by a homeotic conversion of ovules into carpel-like structures. The present observations are consistent with the role of ScFRK2 in pre- and post-fertilization events. Furthermore, overexpression of ScFRK2 led to changes in the expression of the class D floral homeotic gene ScFBP11, suggesting that the ScFRK2 kinase may interact, directly or indirectly, with the FBP7/11 pathway that directs establishment of ovule identity.
Gray-Mitsumune
Madoka
M
Institut de recherche en biologie végétale, Département de sciences biologiques, Université de Montréal, 4101 rue Sherbrooke est, Montréal, Québec, Canada H1X 2B2.
O'Brien
Martin
M
Bertrand
Charles
C
Tebbji
Faiza
F
Nantel
André
A
Matton
Daniel P
DP
D000595:Amino Acid Sequence; D002454:Cell Differentiation / Q000235:genetics; D003001:Cloning, Molecular; D020224:Expressed Sequence Tags; D005306:Fertilization; D005638:Fruit / Q000201:enzymology / Q000235:genetics / Q000254:growth & development; D018506:Gene Expression Regulation, Plant; D018398:Homeodomain Proteins / Q000235:genetics / Q000378:metabolism; D020930:MAP Kinase Kinase Kinases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D020411:Oligonucleotide Array Sequence Analysis; D010802:Phylogeny; D010940:Plant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism; D012639:Seeds / Q000166:cytology / Q000235:genetics / Q000254:growth & development; D016415:Sequence Alignment; D020539:Sequence Analysis, Protein; D015398:Signal Transduction; D032322:Solanum / Q000196:embryology / Q000201:enzymology* / Q000235:genetics
D018398:Homeodomain Proteins; D010940:Plant Proteins; D012333:RNA, Messenger; D020930:MAP Kinase Kinase Kinases