title: Cloning and characterization of tomato leaf senescence-related cDNAs.
abstract: Senescence-related cDNA clones designated SENU1, 4, 5 (senescence up-regulated) and SEND32, 33, 34, 35 and 36 (senescence down-regulated) isolated from a tomato leaf cDNA library [9] were characterized. Southern analysis showed that SEND32 is encoded by a single-copy gene while SEND33, 34, 35, 36 and SENU1 and SENU5 are members of small gene families. DNA and protein database searches revealed that SEND32, SEND35, SENU1 and SENU5 are novel cDNAs of unknown function. SEND33 encodes ferredoxin, SEND34 encodes a photosystem II 10 kDa polypeptide and SEND36 encodes catalase. The SENU4 sequence is identical to the P6 tomato protein previously reported to be pathogenesis-related [46]. The mRNA levels of SENU1, 4 and 5 increased during leaf senescence and SENU1 and SENU5 were also expressed at high levels during leaf development and in other plant organs. The SENU4 mRNA was associated more specifically with leaf senescence, although low expression was also detected in green fruit. The mRNAs for all SEND clones decreased during tomato leaf development and senescence and all except SEND32 were expressed at low levels in other plant organs. The accumulation of mRNA homologous to SENU4 and the decrease in abundance of SEND32 provide good molecular markers for leaf senescence.
authors.affiliation: Department of Physiology and Environmental Science, The University of Nottingham, Loughborough, UK.
authors.forename: I
authors.initials: I
authors.lastname: John
authors.forename: R
authors.initials: R
authors.lastname: Hackett
authors.forename: W
authors.initials: W
authors.lastname: Cooper
authors.forename: R
authors.initials: R
authors.lastname: Drake
authors.forename: A
authors.initials: A
authors.lastname: Farrell
authors.forename: D
authors.initials: D
authors.lastname: Grierson
mesh_terms: D000595:Amino Acid Sequence; D015415:Biomarkers; D002467:Cell Nucleus / Q000378:metabolism; D018076:DNA, Complementary / Q000235:genetics; D015536:Down-Regulation; D005288:Ferredoxins / Q000235:genetics; D018507:Gene Expression Regulation, Developmental; D018506:Gene Expression Regulation, Plant; D015723:Gene Library; D018551:Solanum lycopersicum; D008969:Molecular Sequence Data; D045322:Photosynthetic Reaction Center Complex Proteins / Q000235:genetics; D045332:Photosystem II Protein Complex; D018515:Plant Leaves / Q000254:growth & development*; D012333:RNA, Messenger / Q000235:genetics*; D018749:RNA, Plant / Q000235:genetics*; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid; D014018:Tissue Distribution; D014158:Transcription, Genetic
chemical_list: D015415:Biomarkers; D018076:DNA, Complementary; D005288:Ferredoxins; D045322:Photosynthetic Reaction Center Complex Proteins; D045332:Photosystem II Protein Complex; D012333:RNA, Messenger; D018749:RNA, Plant