Transcriptional and physiological changes in the S assimilation pathway due to single or combined S and Fe deprivation in durum wheat (Triticum durum L.) seedlings

Abstract

The effect of iron (Fe) and sulphur (S) deprivation on sulphate uptake and assimilation pathways was investigated in durum wheat by analysing the expression of genes coding for major transporters and enzymes involved in sulphate assimilation and reduction: high-affinity sulphate transporters (TdSultr1.1 and TdSultr1.3), ATP sulphurylase (TdATPSul1 and TdATPSul2), APS reductase (TdAPR), sulphite reductase (TdSiR), O-acetylserine(thiol)lyase (TdOASTL1 and TdOASTL2), and serine acetyltransferase (TdSAT1 and TdSAT2). Further experiments were carried out to detect changes in the activities of these enzymes, together with the evaluation of growth parameters (fresh biomass accumulation, leaf green values, and total S, thiol, and Fe concentrations). Fe shortage in wheat plants under adequate S nutrition resulted in an S deficiency-like response. Most of the genes of the S assimilatory pathway induced by S deprivation (TdATPSul1, TdAPR, TdSir, TdSAT1, and TdSAT2) were also significantly up-regulated after the imposition of the Fe limitation under S-sufficient conditions. However, the differential expression of genes encoding the two high-affinity transporters (TdSultr1.1 and TdSultr1.3) indicates that the mechanisms of sulphate uptake regulation under Fe and S deficiency are different in wheat. Moreover, it was observed that the mRNA level of genes encoding ATPS, APR, and OASTL and the corresponding enzyme activities were often uncoupled in response to Fe and S availability, indicating that most probably their regulation involves a complex interplay of transcriptional, translational, and/or post-translational mechanisms induced by S and/or Fe deficiency.

A Program for Iron Economy during Deficiency Targets Specific Fe Proteins

“…It is of interest to place our findings in the context of studies that have reported on the general effects of Fe deficiency on chlorophyll synthesis and photosynthesis that have been well documented in the literature (Spiller and Terry, 1980;Andaluz et al, 2006;Nishio and Terry, 1983;Nishio et al, 1985;Sharma, 2007;Timperio et al, 2007;Laganowski et al, 2009;Msilini et al, 2011;Ciaffi et al, 2013;Paolacci et al, 2014;Rodríguez-Celma et al, 2013). Some studies on Fe depletion in plants reported that PSI was the major target of Fe deficiency (Nishio et al, 1985;Timperio et al, 2007), whereas we saw a major effect on the cytochromeb 6 f complex and less on PSI.…”

Critical Function of a Chlamydomonas reinhardtii Putative Polyphosphate Polymerase Subunit during Nutrient Deprivation

“…Moreover, S-depleted Chlamydomonas cells have been used for microarrayand RNA-seq-based transcript abundance studies (Zhang et al, 2004;Nguyen et al, 2008;González-Ballester et al, 2010), determination of metabolite profiles (Bölling and Fiehn, 2005), and the production of H 2 (Ghirardi et al, 2007). Numerous studies of S-deprived plants have also been performed (Lewandowska and Sirko, 2008;Kopriva et al, 2009;Lee et al, 2012;Ciaffi et al, 2013), with some of these that include determinations of transcript levels and metabolite profiles (Hirai et al, 2003;Maruyama Nakashita et al, 2003;Nikiforova et al, 2005aNikiforova et al, , 2005bLunde et al, 2008;Kopriva et al, 2012).…”

Regulation of Phytosiderophore (PS) and Yellow Stripe-1 (YS1) Transporter Activity by Sulphur (S) and that of High-Affinity Sulphate (SULTR1; 1) Transporter by Iron (Fe) in Wheat

“…In addition, it is shown that the S supply in form of sulphate can increase synthesis (Kuwajima and Kawai, 1997) and release of PS in Fe-deficient barley roots to improve the capacity of these plants to cope with Fedeficiency (Römheld and Marschner, 1990). The impact of Fe deprivation on the S assimilation pathway has been recently investigated in durum wheat (Ciaffi et al, 2013). These metallophores although can bind with metals other than Fe and Zn, highest affinity is reported for Fe (III) leading to predominance of Fe-PS complex which is taken up by the roots through YS1/YSL family transporters (Curie et al, 2001).…”

“…A positive effect of sulphur fertilization on growth attributes (Ciaffi et al, 2013), grain yield (Zhao et al, 1999) and grain quality (Pompa et al, 2009) have been evidenced in different crops (Jarvan et al, 2008). Our result confirmed this as the measure of yield and its attributes indicated a positive impact of sulphur application at S30 over S0 condition.…”

“…SULTR1; 1 expression in cortex and epidermis of roots was highly regulated by S deficiency in Arabidopsis (Takahashi et al, 2000;Yoshimoto et al, 2002). Buchner et al, (2010) and Ciaffi et al, (2013) investigated the effect of Fe and S deprivation on expression profile of certain important transporters and enzymes involved in S assimilation and reduction and concluded that Fe-S interaction is a complex interplay of transcriptional/translational and post translational mechanisms that are induced under S/Fe deficiency. Importance of mugineic acid family of PS as Fe (III) chelator to improve Fe uptake from calcareous/alkaline soils is known (Kobayashi et al, 2012).…”