Screening;Cloning And Characteration Of The CDNA Fragment Of Metal Response Element Binding Protein From Wheat

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.