Comparative Analysis of Differentially Expressed Genes in Rice Under Nitrogen and Phosphorus Starvation Stress Conditions

Nitrogen (N) and phosphorus (P) are two major mineral nutrients required for plant growth and development. Deficiencies in N or P results in both morphological and molecular changes such that plants develop adaptive responses to low N or P availability. In this study, we applied the Affymetrix Rice Genome array to analyze the overlap between the differentially expressed gene response to N and P starvation conditions. The results showed that a large number of genes were expressed differentially both under N starvation conditions and under P starvation conditions, including genes encoding a sulfate transporter, Fd-glutamate synthase, peroxidases, transcription factors, kinases and cytochrome P450s. In roots, 61, 42 and 159 genes were significantly up-regulated after 1 h, 24 h and 7 days, respectively, under both N and P starvation conditions, whereas 104, 50 and 166 genes, respectively, were significantly down-regulated. In shoots, 56, 104 and 101 genes were significantly up-regulated after 1 h, 24 h and 7 days, respectively, under both N and P starvation conditions, whereas 15, 80 and 59 genes, respectively, were significantly down-regulated. Generally, these differentially expressed genes belonged primarily to six biological process categories: molecular transport, molecular metabolism, regulation and modification, organism development, stress stimuli and electron transport. Our results may indicate some common physiological and genetic mechanisms in plant responses to environmental variations.