Liu C, Muchhal U S, Raghothama K G
Department of Horticulture, Purdue University, West Lafayette, IN 47907-1165, USA.
Plant Mol Biol. 1997 Mar;33(5):867-74. doi: 10.1023/a:1005729309569.
Plants respond to phosphate (Pi) deficiency through adaptive mechanisms involving several morphological, biochemical and molecular changes. In this study, we have characterized the structure and expression of a tomato (Lycopersicon esculentum L.) phosphate starvation-induced gene (TPSI1). A 3.5 kb genomic fragment containing the 474 bp TPSI1 transcript was isolated. The TPSI1 transcript contains an open reading frame of 174 nucleotides encoding a 58 amino acid polypeptide. TPSI1 is an intron-less gene and only one copy could be detected in the tomato genome. The promoter region of TPSI1 contains several conserved sequences found in phosphate starvation induced genes of yeast. The TPSI1 transcripts are rapidly induced in roots and leaves during Pi starvation. A significant increase in the TPSI1 mRNA was observed in cell cultures and roots after 3 and 12 h of Pi starvation, respectively. Induction of the TPSI1 gene appears to be a response specific to Pi starvation since it is not affected by starvation of other nutrients (nitrogen, potassium and iron). The amount of TPSI1 transcript decreased rapidly when Pi-starved tomato plants were resupplied with Pi. These results suggest that TPSI1 gene expression may be a part of the early Pi starvation response mechanism in plants.
植物通过涉及多种形态、生化和分子变化的适应性机制来应对磷（Pi）缺乏。在本研究中，我们对番茄（Lycopersicon esculentum L.）磷饥饿诱导基因（TPSI1）的结构和表达进行了表征。分离出了一个包含474 bp TPSI1转录本的3.5 kb基因组片段。TPSI1转录本包含一个174个核苷酸的开放阅读框，编码一个58个氨基酸的多肽。TPSI1是一个无内含子的基因，在番茄基因组中只能检测到一个拷贝。TPSI1的启动子区域包含在酵母磷饥饿诱导基因中发现的几个保守序列。在Pi饥饿期间，TPSI1转录本在根和叶中迅速被诱导。分别在Pi饥饿3小时和12小时后，在细胞培养物和根中观察到TPSI1 mRNA显著增加。TPSI1基因的诱导似乎是对Pi饥饿的特异性反应，因为它不受其他营养物质（氮、钾和铁）饥饿的影响。当Pi饥饿的番茄植株重新供应Pi时，TPSI1转录本的量迅速下降。这些结果表明，TPSI1基因表达可能是植物早期Pi饥饿反应机制的一部分。
