Differential gene expression in leaves and roots of winter rape in response to phosphorus starvation

Abstract

Genes induced by phosphorus deficiency in leaves and roots of winter rape (Brassica napus) seedlings were isolated and analyzed. The mRNA differential display technique was used to visualize cDNA fragments derived from the phosphorus-tolerant cv. Zy 821 and the phosphorus-sensitive cv. No. 1182 grown under conditions of phosphorous starvation. Approximately 2000 cDNA bands were visualized by differential display using 78 primer pair combinations. A total of 61 phosphorus-starvation-induced cDNA fragments differentially expressed were isolated. Among these, 40 were derived from roots and only 21 from leaves. Sequence analysis of 16 fragments revealed that they represented distinct cDNAs. A subsample of five cDNAs was analyzed by semi-quantitative RT-PCR, which showed that they were truly different products. Transcripts coding for enzymes involved in photosynthesis (thylakoid membrane phosphoprotein) and root hair initiation (xyloglucan endotransglycosylase), and two regulators (RNA-binding/nucleic acid-binding mRNA and a structural constituent of ribosomal mRNA) were found to be differentially expressed. These results show that the mechanism of cv. Zy 821 adaptation to P starvation is complex. Although its P-tolerance trait is controlled by a major gene, many other genes influencing P acquisition and remobilization, carbon and secondary metabolism, developmental processes, and regulatory pathways are also involved.