Os02g0624300

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Annotated Information

Function

The MYB superfamily is one of the largest plant families (Stracke et al. 2001). MYB proteins are characterized by a conserved MYB DNA-binding domain, which generally includes 1 to 3 imperfect repeats of 50–53 amino acids in the N-terminal region. Based on the number of adjacent repeats in the binding domain, plant MYB proteins are divided into 3 major groups: R1R2R3-MYB, R2R3-MYB, and R1-MYB (Kranz et al. 2000). e functions of MYB proteins in plants are very diverse. Some plant MYB genes are involved in the regulation of secondary metabolism, cellular morphogenesis, and cell cycle (Ma et al. 2009), while others play important roles in the signal transduction responding to plant growth regulators, pathogen infection,and drought (Martin and Paz 1997; Dai et al. 2007). Given the size of the gene family and their roles in plant speci c processes, the MYB family is considered to be particularly important in the transcriptional regulation of plants (Jin and Martin 1999; Shuichi et al. 2011).Arizona ash is a member of the family Oleaceae, which is one of the most important trees in the world. Since Arizona ash is characterized by its ability to tolerate drought and salt conditions, it is widely planted in many areas (Balok and Hilaire 2002).In Arizona ash, few MYB genes have been studied in detail due to its huge and complex genome.The molecular mechanisms of salt tolerance in Arizona ash are not yet clear. Three OsMYBSs were involved in the sugar and hormonal regulation of α-amylase gene expression in cereals (Lu et al. 2002), and the StMYB1R-1 protein, which functioned as a transcription factor involved in the activation of drought-related genes, can enhance drought tolerance via regulation of water loss (Dong et al. 2011). Several plant miRNAs regulate the expression of MYB genes, and speci cally repress the target gene transcripts (Eldem et al. 2012). For example, the myb33 and myb101 mRNAs regulating seed germination could be suppressed by miR159 activity. Over-expression of miR159 resultedin hyposensitivity to abscisic acid (ABA) during seed germination (Jung et al. 2009). Some single-MYB proteins were essential for maintaining telomere length or playing diverse roles in trichome development (Bilaud et al. 1996; Shakirov et al. 2005; Katja et al. 2009).

Expression

The 4-week-old seedlings were transferred into Hoagland's solution with salt (300 mM) for 24 h. e seedlings grown on Hoagland’s solution were used as control.The roots, stems, cotyledons, and leaves were harvested separately and total RNA was reverse transcribed. e synthesized cDNA was used as template in semiquantitative RT-PCR and real-time PCR. For semiquantitative RT-PCR, the resulting cDNA was used as a template for 25 cycles of 30 s at 94 °C, 30 s at 58 °C, 30 s at 72 °C, and a nal extension at 72 °C for 10 min. Ten microliters of the PCR product were electrophoresed and visualized by ethidium bromide staining. Actin was used as a loading control. Primers used in semiquantitative RT-PCR were as follows: forward primer 5′-AGGGTTCATGCTGTTTGG-3′ and reverse primer 5′-GCTATTGTTGTTG GGTGGT-3′. Normalization was carried out by ampli cation of actin mRNA using a forward primer AF: 5′-TCCTCTTCCAGCCTTCTTT-3′ and a reverse primer AR: 5′-TTCCTT GCTCATACGGTCA-3′.Real-time PCR was also conducted using a BIORAD IQ5 (BioRad, USA) qPCR machine and the Maxima SYBR Green qPCR Master Mix (Fermentas) with primers Q-M1F (5′-TGTCGGGTTTCCAGACAATGCAA-3′) and Q-M1R (5′-TTTTCCCCCAACTTTCCAACACA-3′) for FvMYB1. Actin gene was used as housekeeping gene to normalize the target gene quantities.The same primers AF and AR were used for ampli cation of actin gene.The PCR annealing temperature of all primers was 60 °C.The expression level of the FvMYB1 gene was evaluated with respect to actin, which was constitutively expressed.

Evolution

The phylogenetic tree was constructed by neighbor-joining method (Saitou and Nei 1987) based on the R3 domain amino acid sequence.The reliability of the tree was measured by bootstrap analysis with 1000 replicates (Felsenstein 1985). Numbers indicated similarity.The amino acid sequences were obtained from NCBI with the accession numbers as below: Arabidopsis thaliana MYBL2 (AEE35154), AtETC1 (AEE27280), AtTRY (AED96321), AtCPC (AEC10691), AtTCL1 (AEC08388), AtMYB60 (AEE28351), AtMYB2 (BAB62130), AtMYB15 (AEE76740); Oryza sativa OsMYB2 (BAA23338), OsMYB4 (Q7XBH4); Catharanthus roseus CrMYB (ABL63124); Glycine max GmMYB176 (ABH02865), Rosa hybrid cultivar RhMYB (ABU53684), Oryza sativa Japonica Group OsMYBS2(AAN63153), OsMYBS3 (AAN63154); Malus xiaojinensis MxMYB1 (AAO45179); Solanum tuberosum StMYB1R-1 (Q2V9B0).

Labs working on this gene

College of Life Science, Shandong Normal University, Shandong, P.R. China Shandong Provincial Key Laboratory of Genetic Improvement Ecology and Physiology of Crops and Key Laboratory of Crop Genetic Improvement and Biotechnology, Huanghuaihai, Ministry of Agriculture, Hi-Tech Research Center, Shandong Academy of Agricultural Science, Shandong, P.R. China Shandong Provincial Key Laboratory of Eco-Environmental Science for Yellow River Delta, Binzhou University, Shandong, P.R. China

References

Balok CA, Hilaire RS (2002) Drought responses among seven southwestern landscape tree taxa. J Am Soc Hortic Sci 127: 211–218. Boyer LA, Latek RR, Peterson CL (2004) e SANT domain: a unique histone-tail-binding module. Nat Rev Mol Cell Bio 5: 158–163. Dai X, Xu Y, Ma Q, Xu W, Wang T, Xue Y, Kang C (2007) Overexpression of an R1R2R3 MYB gene, OsMYB3R-2, increases tolerance to freezing, drought, and salt stress in transgenic Arabidopsis. Plant Physiol 143: 1739–1751.