Investigation of Differential Expressed Genes Responding to Deficient-Pi in Wheat as Revealed by cDNA-AFLP Analysis

The objective of this study was to disclose the possible mechanism of tolerance to Pi-deficiency in wheat (Triticum aestivum L.) at the gene-expression level. Seedlings of wheat cultivar Shixin 828, which has high phosphorus use efficiency, were treated with 20 µmol L−1 Pi for short (1–6 h), medium (12–48 h), and long terms (72–144 h). The differentially expressed sequence tags (ESTs) were identified using complementary DNA-amplified fragment length polymorphism (cDNA-AFLP) technique. A total of 143 and 94 nonredundant differential ESTs with up- and down-regulated patterns were identified, of which 23, 54, and 66 ESTs enhanced expression after the short-, medium-, and long-term treatments, and 17, 39, and 38 ESTs declined expression after the 3 treatments, respectively. These ESTs were classified into several functional groups according to the BLAST analysis. The up-regulated ESTs, except for 44 with unknown function, confer functions of signal transduction, transcription regulation, metabolism, stress response, development, transport, and lipid metabolism. The down-regulated ESTs are involved in the above functions and protein synthesis and protein degradation. Under the Pi-deficient condition, some genes were specifically up-regulated, such as OsPTF1 and ZAT10 homologues and genes encoding mitogen activated protein kinase, calcium-dependent protein kinase and protein kinase, high-affinity phosphate transporter, peroxidase and glutathione S-transferase. These genes are conjectured to play important roles in promoting adaptation to Pi-deficient environment.

摘 要以磷高效小麦品种石新828为材料, 采用cDNA-AFLP技术, 鉴定了短期(1∼6 h)、中期(12∼48 h)和长期(72∼144 h)低磷胁迫根系特异上、下调表达基因的表达序列标签(EST)。共有非重复的上调ESTs 143个, 下调ESTs 94个。胁迫下的前者分别含短、中和长期23、54和66个; 后者分别含短、中和长期17、39和38个。对其功能比对发现, 上调ESTs在功能上归属于信号转导、转录调控、代谢、逆境响应、发育、物质运输、脂类代谢和功能未知等类别, 下调EST除上述类别外, 还含有蛋白质合成和降解等类别。部分转录因子基因(如水稻OsPTF1和拟南芥ZAT10高度同源的转录因子基因)、促分裂原激酶基因MAPK1a、钙依赖蛋白激酶基因CPK1A和蛋白激酶基因(如serine/threonine kinase)、高亲和磷转运蛋白基因(PHT3和PT2)、过氧化物酶基因(如peroxidase 73)和谷胱甘肽-S-转移酶基因(glutathione S-transferase), 受到低磷胁迫的特异增强诱导, 在改善小麦植株对低磷胁迫的适应能力中可能具有重要作用。研究表明, 小麦对低磷胁迫的响应, 在分子水平上存在着植株感受低磷胁迫信号和信号转导、进一步在生理生化方面对胁迫信号产生应答等复杂的过程。