Cloning of two contrasting high-affinity sulfate transporters from tomato induced by low sulfate and infection by the vascular pathogen Verticillium dahliae

• Published in: Planta 2003-11, Vol.218 (1), p.58-64
• Main Authors: Howarth, Jonathan R., Fourcroy, Pierre, Davidian, Jean-Claude, Smith, Frank W., Hawkesford, Malcolm J.
• Format: Article
• Language: English
• Subjects: Absorption. Translocation of ions and substances. Permeability; Agronomy. Soil science and plant productions; Amino acids; Base Sequence; Biological and medical sciences; Biological Transport; Carrier Proteins - genetics; Carrier Proteins - metabolism; Cell physiology; Cloning; Cloning, Molecular - methods; Complementary DNA; DNA Primers; Economic plant physiology; Epidermis; Fundamental and applied biological sciences. Psychology; Fungal plant pathogens; Genetics; In Situ Hybridization; Infections; Kinetics; Life Sciences; Lycopersicon esculentum - genetics; Lycopersicon esculentum - metabolism; Lycopersicon esculentum - microbiology; Membrane Transport Proteins; Nutrition. Photosynthesis. Respiration. Metabolism; Pathogens; Pathology, epidemiology, host-fungus relationships. Damages, economic importance; Phytopathology. Animal pests. Plant and forest protection; Plant Diseases - microbiology; Plant physiology and development; Plant roots; Plant Roots - metabolism; Plant Roots - microbiology; Plant tissues; Plants; Plants genetics; Plasma membrane and permeation; Stems; Sulfates; Sulfates - metabolism; Sulfur; Tomatoes; Transcription, Genetic - genetics; Vascular tissues; Verticillium - pathogenicity; Yeasts
• ISSN: 0032-0935; 1432-2048
• DOI: 10.1007/s00425-003-1085-5

Two cDNAs, LeST1-1 (AF347613) and LeST1-2 (AF347614), encoding sulfate transporters have been cloned from tomato (Lycopersicon esculentum Mill.) by reverse transcription—polymerase chain reaction and their expression characterised. Sharing 76% identity at the amino acid level, the transporters are phylogenetically associated with the Group-1, high-affinity plant sulfate transporters. Both were shown to have high affinity for sulfate by uptake kinetic analysis using a yeast (Saccharomyces cerevisiae) sulfate-transporter mutant. Km values of 11.5 μM and 9.8 μM were calculated for LeST1-1 and LeST1-2, respectively, the same order of magnitude as those previously reported for several other Group-1 high-affinity sulfate transporters. In situ hybridisation to S-deficient tomato roots showed LeST1-1 to be expressed in the epidermis and pericycle, whereas LeST1-2 expression was located to the epidermis only. Northern analysis shows that the mRNA abundances of both LeST1-1 and LeST1-2 are upregulated in the root in response to sulfate deprivation. LeST1-1 is specifically expressed in root tissue, a characteristic of Group-1 sulfate transporters. LeST1-2, however, was also detected in tomato leaves and stems and is upregulated and expressed to a similar extent in these tissues under conditions of sulfate deprivation. Induction of LeST1-2 expression was also observed in the vascular tissues of a resistant line of tomato infected with the vascular wilt pathogen Verticillium dahliae.