Functional Study Of Wheat MYB Transcription Factors

The proteins of the MYB superfamily play central roles in developmental processes and defenseresponses in plants. Presently, little is known about this gene family in bread wheat. Considering themultiple functions of MYB proteins, we conducted research concerning characterization of thefunctional MYB genes in wheat, which would provide candidate genes for molecular breeding in thefuture. In this study, three abiotic stresses tolerance genes and one heading date related gene wereisolated and studied.A stresses-induced gene, TaMYB19, encodes a R2R3-type MYB protein in wheat. Threehomologous sequences of TaMYB19were isolated from hexaploid wheat and designed as TaMYB19-A,TaMYB19-B and TaMYB19-D genes based on the localizations of these three sequences to chromosomes1A,1B and1D, respectively. The expression levels of these three genes were similar under differentstress conditions. The TaMYB19protein was localized to the nucleus. The detailed characterization ofArabidopsis transgenic plants that overexpress the TaMYB19gene revealed that the TaMYB19proteincan improve different stresses tolerance.A PEG stress-induced gene, TaMYB30, encodes a R2R3-type MYB protein in wheat. Threehomologous sequences of TaMYB30were isolated from hexaploid wheat and designed as TaMYB30-A,TaMYB30-B and TaMYB30-D genes based on the localizations of these three sequences to chromosomes2A,2B and2D, respectively. The expression levels of these three genes were similar under PEG stressconditions. The TaMYB30protein was localized to the nucleus where it activated transcription. Thedetailed characterization of Arabidopsis transgenic plants that overexpress the TaMYB30gene revealedthat the TaMYB30protein can improve drought stress tolerance.TaMYB56encodes a cold stress-related MYB protein in wheat. We isolated the sequences ofTaMYB56genes, and mapped them to the wheat chromosomes3B and3D. The expression levels ofthese two genes were similar under different stress conditions. The TaMYB56protein was localized tothe nucleus where it activated transcription. The detailed characterization of the Arabidopsis transgenicplants that overexpress TaMYB56revealed that TaMYB56is possibly involved in the responses of plantto freezing and salt stresses.A heading date related gene, TaMYBX, was identified in this study. TaMYBX encodes aMYB-related protein, which makes the heading date of transgenic rices earlier12-15days. Threehomologous sequences of TaMYBX were isolated from hexaploid wheat and designed as TaMYBX-A,TaMYBX-B and TaMYBX-D genes based on the localizations of these three sequences to chromosomes6A,6B and6D, respectively. The TaMYBX protein was localized to the nucleus and sharedtranscriptional activation activity. After analysys of the phenotypic traits of T2generation transgenicrice, we found that TaMYBX have pleiotropic effects on heading date, plant height, yield and other traits.