Sulphur deprivation limits Fe-deficiency responses in tomato plants.
The aim of this work was to clarify the role of S supply in the development of the response to Fe depletion in Strategy I plants. In S-sufficient plants, Fe-deficiency caused an increase in the Fe(III)-chelate reductase activity, 59Fe uptake rate and ethylene production at root level. This response was associated with increased expression of LeFRO1 [Fe(III)-chelate reductase] and LeIRT1 (Fe2+ transporter) genes. Instead, when S-deficient plants were transferred to a Fe-free solution, no induction of Fe(III)-chelate reductase activity and ethylene production was observed. The same held true for LeFRO1 gene expression, while the increase in 59Fe2+ uptake rate and LeIRT1 gene over-expression were limited. Sulphur deficiency caused a decrease in total sulphur and thiol content; a concomitant increase in 35SO4(2-) uptake rate was observed, this behaviour being particularly evident in Fe-deficient plants. Sulphur deficiency also virtually abolished expression of the nicotianamine synthase gene (LeNAS), independently of the Fe growth conditions. Sulphur deficiency alone also caused a decrease in Fe content in tomato leaves and an increase in root ethylene production; however, these events were not associated with either increased Fe(III)-chelate reductase activity, higher rates of 59Fe uptake or over-expression of either LeFRO1 or LeIRT1 genes. Results show that S deficiency could limit the capacity of tomato plants to cope with Fe-shortage by preventing the induction of the Fe(III)-chelate reductase and limiting the activity and expression of the Fe2+ transporter. Furthermore, the results support the idea that ethylene alone cannot trigger specific Fe-deficiency physiological responses in a Strategy I plant, such as tomato.
Dipartimento di Agrobiologia e Agrochimica, Università della Tuscia, Via S. C. de Lellis, 01100 Viterbo, Italy.
Sabrina
S
Zuchi
Stefano
S
Cesco
Zeno
Z
Varanini
Roberto
R
Pinton
Stefania
S
Astolfi
D002118:Calcium / Q000378:metabolism; D027682:Cation Transport Proteins / Q000235:genetics; D005030:Ethylenes / Q000378:metabolism; D038181:FMN Reductase / Q000235:genetics; D018507:Gene Expression Regulation, Developmental; D018506:Gene Expression Regulation, Plant; D017136:Ion Transport; D007501:Iron / Q000378:metabolism*; D007504:Iron Radioisotopes / Q000378:metabolism; D018551:Solanum lycopersicum / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D008274:Magnesium / Q000378:metabolism; D018515:Plant Leaves / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D010940:Plant Proteins / Q000235:genetics; D018517:Plant Roots / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D011188:Potassium / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012964:Sodium / Q000378:metabolism; D013431:Sulfates / Q000378:metabolism; D013438:Sulfhydryl Compounds / Q000378:metabolism; D013455:Sulfur / Q000378:metabolism*; D013462:Sulfur Radioisotopes / Q000378:metabolism
D027682:Cation Transport Proteins; D005030:Ethylenes; D007504:Iron Radioisotopes; D010940:Plant Proteins; D013431:Sulfates; D013438:Sulfhydryl Compounds; D013462:Sulfur Radioisotopes; D013455:Sulfur; C036216:ethylene; D012964:Sodium; D007501:Iron; D038181:FMN Reductase; C023903:ferric citrate iron reductase; D008274:Magnesium; D011188:Potassium; D002118:Calcium