A gene encoding a novel isoform of the PR-1 protein family from tomato is induced upon viroid infection

A Lycopersicon esculentum cDNA clone encoding an acidic-type pathogenesis-related protein (PR-lal) was isolated, sequenced and characterized. It contains an open reading frame of 175 amino acids and the mature protein, after cleavage of the 21 amino acid signals peptide, has a pl of 5.24. The protein shows highest homology (75% identity) with the basic pathogenesis-related prb-lb protein from tobacco. The PR-lal gene shows constitutive expression in roots from tomato plants. It is expressed in leaves and stems upon viroid infection, and appears to be induced by ethylene. Comparative studies of this gene and a related basic isoform of PR-1 indicate that the expression of these two members of the PR-1 gene family in tomato may be differentially regulated upon viroid infection.The nucleotide sequence data reported in this paper will appear in the EMBL, GenBank and DDBJ Nucleotide Sequence Databases under the accession number X71592.     

Structure and expression of an ethylene-related mRNA from tomato.

Messenger RNAs homologous to a cDNA clone (pTOM 13) derived from a ripe-tomato-specific cDNA library are expressed during tomato fruit ripening and after the wounding of leaf and green fruit material. Both responses involve the synthesis of the hormone ethylene. Accumulation of the pTOM 13--homologous RNA during ripening is rapid and sustained, and reaches its maximum level in orange fruit. Following mechanical wounding of tomato leaves a pTOM 13--homologous RNA shows rapid induction within 30 minutes, which occurs before maximal ethylene evolution (2-3 h). This RNA also accumulates following the wounding of green tomato fruit. Northern blot analysis of poly(A)+ RNA indicates that the length of the mRNA is about 1400 nucleotides. Nucleotide sequence analysis showed the cDNA insert to contain the complete coding region of the pTOM 13 protein (33.5 kD) and an unusual 5' structure of ten dT-nucleotides. Hybridisation of the pTOM 13 cDNA insert to Southern blots of tomato DNA indicates the presence of only a small number of homologous sequences in the tomato genome.     

A Calcium-Dependent Protein Kinase Is Systemically Induced upon Wounding in Tomato Plants

A full-length cDNA clone (LeCDPK1) from tomato (Lycopersicon esculentum) encoding a calcium-dependent protein kinase (CDPK) was isolated by screening a cDNA library from tomato cell cultures exposed to Cladosporium fulvum elicitor preparations. The predicted amino acid sequence of the cDNA reveals a high degree of similarity with other members of the CDPK family. LeCDPK1 has a putative N-terminal myristoylation sequence and presents a possible palmitoylation site. The in vitro translated protein conserves the biochemical properties of a member of the CDPK family. In addition, CDPK activity was detected in soluble and particulate extracts of tomato leaves. Basal levels of LeCDPK1 mRNA were detected by northern-blot analysis in roots, stems, leaves, and flowers of tomato plants. The expression of LeCDPK1 was rapidly and transiently enhanced in detached tomato leaves treated with pathogen elicitors and H2O2. Moreover, when tomato greenhouse plants were subjected to mechanical wounding, a transient increase of LeCDPK1 steady-state mRNA levels was detected locally at the site of the injury and systemically in distant non-wounded leaves. The increase observed in LeCDPK1 mRNA upon wounding correlates with an increase in the amount and in the activity of a soluble CDPK detected in extracts of tomato leaves, suggesting that this kinase is part of physiological plant defense mechanisms against biotic or abiotic attacks.     

Nucleotide sequence and expression of a ripening and water stress-related cDNA from tomato with homology to the MIP class of membrane channel proteins

The nucleotide sequence and derived amino acid sequence were determined for a full-length version of the tomato cDNA clone, pTOM75, the mRNA for which has previously been shown to accumulate in roots, ripening fruit and senescing leaves. Computer analysis of the predicted protein product, which we have named tomato ripening-associated membrane protein (TRAMP) indicates strong homology to known transmembrane channel proteins from other organisms. Northern analysis showed that this gene was induced by waterstress and that this induction was unaffected in an ABA-deficient genetic back-ground.     

Fruit ripening-related expression of a gene encoding group 5 late embryogenesis abundant protein inCitrus

A cDNA and genomic clone (CuLEA5) encoding a group 5 late embryogenesis abundant protein (Lea5) was isolated from citrus fruit cDNA and genomic libraries. Sequence analysis indicated that the clone contains an open reading frame of 97 amino acids, and that the genomic structure is composed of two exons and one intron. A comparison of its amino sequence with other plant proteins showed that Lea5 proteins can be classified into two types - gymnosperm and angiosperm — based on a P-segment sequence designated by this study. Examination of its expression patterns indicated thatCuLEA5 has important roles during the development or ripening of seedless fruits and leaves inCitrus. The 5′-flanking region of the genomic DNA contains a number of putative hormonal- and stress-responsive elements. This is the first report that describes the expression ofLea5 during fruit ripening, as well as the sequence characteristics of its promoter region.     

Molecular cloning and characterization of a cDNA for a novel ethylene receptor, NT-ERS1, of tobacco (Nicotiana tabacum L.)

The cDNA encoding a novel member (NT-ERS1) of ethylene receptor family of tobacco (Nicotiana tabacum L.) was obtained by a combination of RT-PCR and 5'-/3'-RACE cloning. The cDNA was 2,092 nucleotides long and had an open reading frame of 1,911 bp encoding 637 amino acids. The deduced polypeptide lacked a response regulator domain, indicating that the ethylene receptor belongs to an ERS-group. The amino acid sequence was similar to respective members of the tobacco ethylene receptor family: 67.8% to NT-ETR1, 39.1% to NTHK1 and 31.1% to NTHK2. Comparison of amino acid sequence suggested that NT-ERS1 is the counterpart of Nr in the ethylene receptor family of tomato, which belongs to Solanaceae as does tobacco. Northern blot analysis showed that mRNA of NT-ERS1 was present in leaf, shoot and root tissues, and accumulated in leaves treated with exogenous ethylene. A mutated NT-ERS1 cDNA transgene, obtained by introducing one nucleotide substitution into NT-ETR1 cDNA, conferred ethylene insensitivity in tobacco plants, indicating that the translation product of the cDNA actually functioned in the plants.     

Drought,heat and salt stress induce the expression of a citrus homologue of an atypical late-embryogenesis Lea5 gene

In a search for genes that are induced in citrus cell suspension in response to salt stress, a cDNA clone with high homology to cotton Lea5 gene was isolated. Data base analysis of the protein deduced from the nucleotide sequence indicates that, like in cotton, the protein from citrus contains regions with significant hydropathic character. The gene, designated C-Lea5, is expressed in citrus leaves as well as cell suspension. The steady-state level of C-Lea5 is increased in cell suspension that is grown in the presence of 0.2 M NaCl. This phenomenon is also observed in leaves of citrus plants irrigated with NaCl and in citrus seedlings which are exposed to drought and heat stress. We suggest that the osmotic stress resulted from elevated level of salt is responsible for the increase in the level of C-Lea5.     

桃ACC合酶基因的分离及其差异表达

利用5′/3′RACE PCR技术,从桃(Prunus persica (L.) Batsch)果实中克隆了植物乙烯生物合成的关键酶--ACC合酶的全长cDNA pacs,对pacs基因进行全序列测定表明,该基因全长1 848个碱基,编码区为1 449个碱基,5′端有177个碱基的非编码区序列,3′端有219个碱基的非编码区序列(不包括终止密码子TAA).pacs基因编码区共编码483个氨基酸,蛋白质大小为54 kD,等电点为6.43.pacs与番茄(S19677)、梅(AB031026)、番木瓜(U68216)、苹果(AB034993)等其他植物ACC合酶cDNA氨基酸序列同源性分别为65%、70%、75%、90%,并存在与这些ACC合酶氨基酸的活性位点保守序列SLSKDMGFPGFR.RT-PCR结合杂交分析表明,pacs和我们以前克隆的桃ACC合酶cDNA pacs12(AF467782)在叶片和花中基因表达模式基本一致,伤处理和IAA均能诱导叶片pacs 和pacs12基因的表达,但pacs在伤处理叶片的表达水平比pacs12高;pacs 和pacs12基因在果实表达有所不同,pacs在绿熟和成熟果实中均有表达,而pacs12在绿熟果实中基本检测不到,在成熟果实中才有表达,两者在果实中的表达水平比伤处理和IAA处理叶片和花中要低.     

Cloning, sequence, and expression of a cDNA encoding hamster UDP-GlcNAc:dolichol phosphate N-acetylglucosamine-1-phosphate transferase

UDP-GlcNAc:dolichol phosphate N-acetylglucosamine-1-phosphate transferase (GPT) catalyzes the initial reaction required for synthesis of dolichol-P-P-oligosaccharides. We report here on the sequence and expression of a full-length cDNA clone encoding hamster GPT. The cDNA predicts a protein of 408 amino acid residues including 10 hydrophobic segments. Several portions of the hamster GPT sequence constituting one-third of the protein have 60% or greater identity with yeast GPT, and one-half of the conserved sequence falls within the hydrophobic segments. In addition, hamster GPT has two copies of a putative dolichol recognition sequence recently identified in three yeast enzymes that interact with dolichol. The protein lacks KDEL or DEKKMP-type carboxyl-terminal ER sorting sequences. When expressed in COS-1 cells, the cDNA causes a 5-7-fold increase of GPT activity in membrane fractions. The activity was completely inhibitable by tunicamycin, and the primary product was shown to be GlcNAc-pyrophosphoryldolichol. This cDNA represents the first enzyme of the dolichol-oligosaccharide biosynthetic pathway to be cloned from a vertebrate source and demonstrates structural homology between the enzymes of the yeast and mammalian pathways.