Differential expression of maize sugar responsive genes in response to iron deficiency

Substractive screening of a root cDNA library from Fe deficient maize plant s led to isolate a Sus1 cDNA encoding for sucrose synthase (UDP-glucose:D f ructose 2-alpha-D-glycosyl-transferase, EC 2.4.1.13). Northern analysis sho wed that Sus1 mRNA abundance increased in response to iron deficiency in ma ize roots, whereas abundance of two other sugar responsive transcripts, Sh1 sucrose synthase and pZSS6 metallothionein mRNAs, decreased under these co nditions. These mRNA abundance variations have been correlated to increased sugar concentrations in iron deficient maize roots. In contrast in maize l eaves, glucose and fructose, but not sucrose content, decreased in response to iron deficiency, mRNA abundance of Sus1, but also of HI and CSII encodi ng for a histone and a cytoplasmic ribosomal proteins, respectively, was de creased in maize iron deficient leaf sheaths compared to iron sufficient pl ants. The general conclusion of this work points out a differential alterat ion of sugar metabolism and sugar responsive gene expression between leaves and roots in response to iron deficiency. (C) 1999 Editions scientifiques et medicales Elsevier SAS.