http://http://dspace.unitus.it:80 The DSpace digital repository system captures, stores, indexes, preserves, and distributes digital research material. 2013-05-21T12:12:08Z http://hdl.handle.net/2067/1817 Title: Supply of sulphur to S-deficient young barley seedlings restores their capability to cope with iron shortage Authors: Astolfi, Stefania; Zuchi, Sabrina; Hubberten, Hans-Michael; Pinton, Roberto; Hoefgen, Rainer Abstract: The effect of the S nutritional status on a plant’s capability to cope with Fe shortage was studied in solution cultivation experiments in barley (Hordeum vulgare L. cv. Europa). Barley is a Strategy II plant and responds to Fe deficiency by secretion of chelating compounds, phytosiderophores (PS). All PS are derived from nicotianamine whose precursor is methionine. This suggests that a long-term supply of an inadequate amount of S could reduce a plant’s capability to respond to Fe deficiency by limiting the rate of PS biosynthesis. The responses of barley (Hordeum vulgare L. cv. Europa) plants grown for 12 d on Fe-free nutrient solutions (NS) containing 0 or 1.2 mM SO22 4 , was examined after 24 h or 48 h from transfer to NS containing 1.2 mM SO22 4 . After the supply of S was restored to S-deprived plants, an increase in PS release in root exudates was evident after 24 h of growth in S-sufficient NS and the increment reached values up to 4-fold higher than the control 48 h after S resupply. When S was supplied to S-deficient plants, leaf ATPS (EC 2.7.7.4) and OASTL (EC 4.2.99.8) activities exhibited a progressive recovery. Furthermore, root HvST1 transcript abundance remained high for 48 h following S resupply and a significant increase in the level of root HvYS1 transcripts was also found after only 24 h of S resupply. Data support the idea that the extent to which the plant is able to cope with Fe starvation is strongly associated with its S nutritional status. In particular, our results are indicative that barley plants fully recover their capability to cope with Fe shortage after the supply of S is restored to S-deficient plants. Description: L'articolo é disponibile sul sito dell'editore: http://www.jxb.oxfordjournals.org 2009-12-31T23:00:00Z http://hdl.handle.net/2067/1818 Title: Sulphur deprivation limits Fe-deficiency responses in tomato plants Authors: Zuchi, Sabrina; Cesco, Stefano; Varanini, Zeno; Pinton, Roberto; Astolfi, Stefania Abstract: 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 35SO42- 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 of 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. Description: L'articolo é disponibile sul sito dell'editore: http://www.springerlink.com 2008-12-31T23:00:00Z