Comparative genomic and physiological analysis of nutrient response to [graphic removed] , [graphic removed] : [graphic removed] and [graphic removed] in barley seedlings
2008
Lopes, Marta S. | Araus, José L.
Long-term differences in photosynthesis, respiration and growth of plants receiving distinct nitrogen (N) sources imply that N metabolism generates signals that regulate metabolism and development. The molecular basis of these signals remains unclear. Here we studied the gene expression profiles of barley (Hordeum vulgare L. cv. Graphic) seedlings fertilized either with ammonium ( [graphic removed] ), with ammonium and nitrate ( [graphic removed] : [graphic removed] ), or with nitrate ( [graphic removed] ) only. Our transcriptome analysis after 48 h of growth in these N sources showed major changes in the expression of genes involved in N metabolism (nitrate reductase), signalling (protein kinases and protein phosphatases), photosynthesis (chlorophyll a/b-binding protein and a PsbQ domain), where increases in [graphic removed] as compared with [graphic removed] were observed. Moreover, [graphic removed] assimilation induced genes participating in C and sugars metabolism (phosphoglycerate kinase, glucosyltranferase and galactokinase), respiration (cytochrome c oxidase), protein fate (heat shock proteins) and development (MTN3-like protein). These changes in gene expression could well explain the long-term growth depression observed in [graphic removed] plants. Even if a few genes participating in protein fate (proteases) and development (OsNAC5) were upregulated in [graphic removed] as compared with [graphic removed] : [graphic removed] , the general pattern of expression was quite similar between these two N sources. Taken together, these results indicated that other downstream mechanisms should be involved in the synergetic long-term response of [graphic removed] : [graphic removed] .
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