Root physiological and transcriptional response to single and combined S and Fe deficiency in durum wheat

A number of connections and insights are emerging regarding the molecular and physiological basis of Fe and S interplay response of combined Fe and S starvation of durum wheat roots are here presented. Microarray analysis revealed that 128 transcripts were commonly modulated by both single and combined deficiencies, thus representing the “core” set of transcripts involved in the responses both to S and Fe shortage, whereas a total of 509 transcripts were modulated only by the simultaneous deficiency of S and Fe. Interestingly, among these latter, most of the genes of nitrate uptake and assimilation were down-regulated, while those involved into ammonium uptake were up-regulated as confirmed by the decrease in nitrate reductase enzyme activity. Transcripts playing a role into phosphate uptake were down-regulated in agreement with the observed lower P accumulation in roots. Combined deficiency mainly up-regulated transcripts involved with oxidative stress response although the related enzyme activities did not appear to differ significantly. Results allowed the identification of transcripts that are specific as well as those that are shared among single and combined deficiency responses, thus providing a starting point for detailed studies on candidate genes to improve the understanding of the molecular basis of nutrient acquisition.