【作者】 陈晓红；

【导师】 黄勤妮； 印莉萍；

【作者基本信息】 首都师范大学 ， 植物生理学， 2000， 硕士

【摘要】 已有实验证明金属反应元件（metal response element，MRE）在缺铁胁迫诱导的基因表达中起到非常重要的作用。本文从Ids1和Ids2基因5’上游的MRE出发，人工合成长度为74bp的MRE异源三联体。利用³²P末端标记的MRE异源三联体直接筛选小麦缺铁诱导根λgt11-cDNA表达文库，克隆得到了编码其结合蛋白的长度为279bp的cDNA片段，命名为TaMRE-BP cDNA。该cDNA片段和烟草AVR9激发子应答蛋白（AVR9 elicitor response protein）cDNA的相应序列有78％的同源性，TaMRE-BP和烟草AVR9激发子应答蛋白在氨基酸水平上有75％的同源性。经Northern印迹分析，TaMRE-BP cDNA片段的杂交信号在大约1.5kb处，其相应基因的转录活性在缺铁处理第9天的根和叶中明显增强，在缺铁处理第13天的根和叶中稍有减弱，和正常处理时的转录活性相当。Southern印迹分析结果表明TaMRE-BP cDNA片段的相应基因存在于小麦基因组中。 据推测TaMRE-BP可能作为一种MRE结合蛋白参与应答植物体内Fe/Cu水平的变化。缺铁胁迫改变植物体内的Fe/Cu水平（植物体内Fe含量下降，Cu含量上升），进一步诱导该TaMRE-BP cDNA片段相应基因的转录活性，以调节植物体内的金属营养元素的平衡。该基因的转录活性在缺铁处理第9天的根和叶中明显增强，而这时麦根酸的分泌量最大，因此该基因的表达和麦根酸的合成可能有某种联系。TaMRE-BP cDNA片段和烟草AVR9激发子应答蛋白（AVR9 elicitorresponse protein）cDNA有78％的同源性，其原因可能是类似AVR9作用的诱发子改变小麦体内Fe/Cu水平，从而诱导该基因的转录。更多还原

【Abstract】 Previous experiments have established that a cis-acting element named MIRE (Metal Response Element, MRE ) plays an important role in Fe-deficiency-induced gene expression. In this study, three copy of MIRE of 74bp was synthesized and 5?end 32 was labeled by P. A eDNA fragment of 279bp named TaMRE-BP eDNA was cloned by direct screening Fe-deficient wheat root Xgtl 1-eDNA expression library with the labeled MIRE. The eDNA exhibits 78% similarity to the eDNA of AVR9 elicitor response protein and the deduced amino acid sequence exhibits 75% similarity to that of AVR9 elicitor response protein. Northern blotting reveals that the whole length of its eDNA is about 1.5kb. On the 9th day of Fe-deficiency treatment, compared with the normal treatment control, its transcription activity in roots and leaf is apparently elevated. While 13th day the transcription activety is decreased. Southern blotting reveals that this gene is wheat genomic gene. It is assumed that TaMRE-BP response to the change of Fe/Cu level as a MIRE-binding protein in wheat. Fe deficiency treatment changes Fe/Cu level in plant ( Cu level elevated and Fe level decreased ) . This change tbrther induces the transcription activity of this gene to regulate the balance of metal level. As its transcription activity is apparently elevated on the 9th day of Fe-deficiency treatment, the synthesis of mugineic acid is significantly increased this time. Therefore it抯 assumed that TaMRE-BP has something with the synthesis of mugineie acid. As to its high similiarity to the cDNA of AVR9 elicitor response like protein. It抯 predicted that AVR9 like elicitor may indirectly changes Fe/Cu level in wheat, and induces the transcription activity of this gene.更多还原