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LeCTR1, a Tomato CTR1-Like Gene, DemonstratesEthylene Signaling Ability in Arabidopsis and NovelExpression Patterns in Tomato

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Leclercq, Julie | Adams-Phillips, Lori | Zegzouti, Hicham | Jones, Brian | Latché, Alain | Giovannoni, Jim | Pech, Jean-Claude | Bouzayen, Mondher

Edité par CCSD ; Oxford University Press ; American Society of Plant Biologists -

International audience. LeCTR1 was initially isolated by both differential display reverse transcriptase-polymerase chain reaction screening fortomato (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 ethylenereceptor and showing similarity to the Raf family of serine/threonine protein kinases. The length of the LeCTR1 transcribedregion from ATG to stop codon (12,000 bp) is more than twice that of Arabidopsis CTR1 (4,700 bp). Structural analysisreveals perfect conservation of both the number and position of introns and exons in LeCTR1 and Arabidopsis CTR1. Theintrons in LeCTR1 are much longer, however. To address whether this structural conservation is indicative of functionalconservation 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 Arabidopsisctr1-1 mutant can restore normal ethylene signaling. The recovery of normal ethylene sensitivity upon heterologousexpression of LeCTR1 was also confirmed by restored glucose sensitivity absent in the Arabidopsis ctr1-1 mutant. Expressionstudies confirm ethylene responsiveness of LeCTR1 in various tissues, including ripening fruit, and may suggest theevolution of alternate regulatory mechanisms in tomato versus Arabidopsis.

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