LeCTR1, a tomato CTR1-like gene, demonstrates ethylene signaling ability in Arabidopsis and novel expression patterns in tomato.
LeCTR1 was initially isolated by both differential display reverse transcriptase-polymerase chain reaction screening for tomato (Lycopersicon esculentum) fruit ethylene-inducible genes and through homology with the Arabidopsis CTR1 cDNA. LeCTR1 shares strong nucleotide sequence homology with Arabidopsis CTR1, a gene acting downstream of the ethylene receptor and showing similarity to the Raf family of serine/threonine protein kinases. The length of the LeCTR1 transcribed region from ATG to stop codon (12,000 bp) is more than twice that of Arabidopsis CTR1 (4,700 bp). Structural analysis reveals perfect conservation of both the number and position of introns and exons in LeCTR1 and Arabidopsis CTR1. The introns in LeCTR1 are much longer, however. To address whether this structural conservation is indicative of functional conservation of the corresponding proteins, we expressed LeCTR1 in the Arabidopsis ctr1-1 (constitutive triple response 1) mutant under the direction of the 35S promoter. Our data clearly show that ectopic expression of LeCTR1 in the Arabidopsis ctr1-1 mutant can restore normal ethylene signaling. The recovery of normal ethylene sensitivity upon heterologous expression of LeCTR1 was also confirmed by restored glucose sensitivity absent in the Arabidopsis ctr1-1 mutant. Expression studies confirm ethylene responsiveness of LeCTR1 in various tissues, including ripening fruit, and may suggest the evolution of alternate regulatory mechanisms in tomato versus Arabidopsis.
Leclercq
Julie
J
Unité Mixte de Recherche 990, Institut National de la Recherche Agronomique/Institut National Polytechnique-Ecole Nationale Supérieure Agronomique, Boite Postale 107 Auzeville, 31326 Castanet Tolosan cedex, France.
Adams-Phillips
Lori C
LC
Zegzouti
Hicham
H
Jones
Brian
B
Latché
Alain
A
Giovannoni
James J
JJ
Pech
Jean-Claude
JC
Bouzayen
Mondher
M
D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000235:genetics*; D003001:Cloning, Molecular; D005030:Ethylenes / Q000494:pharmacology*; D005638:Fruit / Q000187:drug effects / Q000235:genetics; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D005816:Genetic Complementation Test; D005947:Glucose / Q000378:metabolism; D018551:Solanum lycopersicum / Q000187:drug effects / Q000235:genetics*; D008969:Molecular Sequence Data; D009154:Mutation; D010641:Phenotype; D010940:Plant Proteins / Q000235:genetics*; D030821:Plants, Genetically Modified; D017346:Protein Serine-Threonine Kinases / Q000235:genetics; D012333:RNA, Messenger / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D015398:Signal Transduction / Q000235:genetics / Q000502:physiology
D005030:Ethylenes; D010940:Plant Proteins; D012333:RNA, Messenger; C036216:ethylene; D017346:Protein Serine-Threonine Kinases; D005947:Glucose