Introduction.………………………………………...

• Oxygen deficiency associated with waterlogging in the field is one of the major problems in the crop growing areas. The appropriate signaling pathway under oxygen deficiency may help a successful adaptation to change in O2 concentration.………..

• In a previous study, we analyzed 1,344 clones from the cDNA library of hypoxia-stressed wheat roots and registered 1,274 ESTs in the GenBank database (accession nos. DN828708 - DN829789 and DN948989 - DN949180). Several clones including a clone (accession no. DN828996) that shared high homology with a Myb transcription factor gene exhibited various expressions in roots under hypoxia.…..……………………………………..

• We have analyzed and report our results for the tissue specific transcription of the Myb transcription factor gene in wheat roots under oxygen deficiency treatment and abiotic stresses.

Results and Discussion.…………………………………………………………………………….…………

• A clone (accession no. DN828996) contained a 750-bp open reading frame (ORF) encoding for the putative Myb transcription factor with 250 amino acids. This clone was designated as TaMyb1 (Triticum aestivum Myb transcription factor 1).……………………………………………………………………………..

• Presence of TaMyb1 on the 3BL was confirmed by using Chinese Spring aneuploid accessions including nullisomic-tetrasomic and ditelosomic lines.….............……………………………………………...

• Dramatic increases in the transcripts of a TaMyb1 occurred under hypoxia. The transcriptional expression of TaMyb1 was continued until approximate anoxia, being enhanced by light under hypoxia, but little expression during anoxia could be shown by Northern blot hybridization. Under normoxic condition, the presence or absence of light did not affect expression of TaMyb1.………………………....

• In situ hybridization of the hypoxic stressed radicle showed that TaMyb1 expression was occurred in the epidermis, endodermis, and cortex which was in contact with the endodermis...………………………

• TaMyb1 transcription levels in roots gradually increased as the result of treatment with NaCl.………..

• The results of our Northern blot analysis and tissue specific hybridization revealed that TaMyb1 expression was strongly related to the oxygen concentration in root environment and the responses to the abiotic stresses in the wheat roots. …………………………………………………………………………

Acknowledgement…………………………………………

This work was financially supported by the grant from the Proton Engineering Frontier Project, KAERI, Republic of Korea. This work was partially supported by a grant (20050301-034-432-006-01-00) from BioGreen 21 Program, Rural Development Administration, Republic of Korea.………………………………………………………….

* This study has been accepted in Physiologia Plantarum (PPL-2006-00042.R2).

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169169169146144180

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TaMyb1Myb1MybHv1Zm38R2R3 Myb proteinArabidopsis

TaMyb1Myb1MybHv1Zm38R2R3 Myb proteinArabidopsis

TaMyb1Myb1MybHv1Zm38R2R3 Myb proteinArabidopsis

TaMyb1Myb1MybHv1Zm38R2R3 Myb proteinArabidopsis

TaMyb1Myb1MybHv1Zm38R2R3 Myb proteinArabidopsis

Fig. 1. Amino acid sequence alignment of TaMyb1 with those of other plant Myb transcription factors. Accession numbers: TaMyb1 (wheat, DN828996), transcription factor Myb1 (wheat, AAT37167), MybHv1 (barley, CAA50224), Myb-related protein Zm38 (maize, P20025), typical P-type R2R3 Myb protein (rice, AAL84628), AtMYB2 (Arabidopsis, BAA03534).…………………………………………………………...

Fig. 2. Chromosomal localization of TaMyb1 in aneuploid lines of Chinese Spring. …………………………………………………

Fig. 3. Oxygen deficiency treatment and Northern blot hybridization of TaMyb1. (A) Changes in O2 concentration and pH in the solution as treatment time progresses. O2 is presented as a measure of the concentrations of dissolved O2 (mol m-3). The values are means of three replicates ±s.e. (B) Northern blot hybridization of the TaMyb1 and PDC under oxygen deficiency treatment. (C) Northern blot hybridization of the TaMyb1 under oxygen deficient condition combined with dark treatment. (D) Northern blot hybridization of the TaMyb1 under oxygen deficiency, darkness, together with cutting treatment in the roots. (E) Northern blot hybridization of the TaMyb1 under dark condition (normoxia, DOC: > 0.06 mol m-3) in the roots. h, hour(s); d, day(s); C, control; T, treatment; D, dark conditions; L, light conditions; N, normoxia; DOC, dissolved oxygen concentration; PDC, pyruvate decarboxylase. ………………………………………………………………………………………………………………..

Fig. 4. In situ hybridization of the TaMyb1 mRNA in radicle of control and hypoxia-stressed wheat. Radicles from the control (A) and anaerobic stressed (B, C, and D) plants were collected under hypoxia (DOC: 0.011 mol m-3). Solid arrowheads indicate a high positive signal. Magnifications are ×400 (A and B) and ×1000 (C and D). AE, aerenchyma; C, cortex; D, epidermis; E, endodermis; MX, metaxylem; P, phloem; PC, pericycle; PX, protoxylem. Bars = 100 ㎛ . …...

Fig. 5. Northern blot hybridization of TaMyb1 in seminal roots treated with citric acid (10 mM), NaCl (250 mM), polyethylene glycol (PEG, 25%) or ABA (100 µM). h, hours; C, control; T, treatment. …………………………………………

rRNA

NaCl

PEG

Citric acid

ABA

0 18 24 36 48 0 18 24 36 48

C TTime (h)D

MX

PXP

PXC MX

PCE

AE

B

PC

AE

MX

EAE

D

A

PCE

C

D

MX

N1D-T1B N3D-T3AN6A-T6D N3B-T3DN6D-T6B

N7B-T7AN2B-T2DN3A-T3D N6B-T6D

N1B-T1AN4A-T4B

N5D-T5B

M

TaMyb1

Dt3BLN2D-T2AN5B-T5AN7A-T7BN5A-T5D

N1A-T1B N7D-T7AN3D-T3B

D

TaMyb1

rRNA

Time (d) 0 1 2 4 E

0 12 18 21 (h)

rRNA

NL

ND

DOClight

rRNA

C

TaMyb1

rRNA

Time (d)

0.047 0.016DOC (mol m-3):

0 1 2 4

B0 1 2 4 5 0 1 2 4 5

PDC

TaMyb1

rRNA

0.042 0.037 0.033 0.011 0.011 DOC (mol m-3):

Time (d)

C T

0.000

0.020

0.040

0.060

0.080

0.100

0.120

0.140

0.160

0.180

0 1 2 4 5

3.50

4.00

4.50

5.00

5.50

6.00

6.50

7.00

7.50

oxygen deficiency (DO)

oxygen deficiency+dark (DO)

oxygen deficiency+dark+cutting (DO)

oxygen deficiency (pH)

oxygen deficiency+dark (pH)

oxygen deficiency+dark+cutting (pH) pH

O2 concentration (mol m-3)

Time (days)

A

Molecular characterization of Myb transcription factor (TaMyb) gene that is expressed in response to hypoxic condition in wheat (Triticum aestivum L.) roots

Tong Geon Lee1, Cheol Seong Jang1, Jae Yoon Kim1, Jae Han Park1, Dae Yeon Kim1, Dong Sub Kim2, and Yong Weon Seo1

(1) Division of Biotechnology and Genetic Engineering, Korea University, Anam-Dong, Seongbuk-Gu, Seoul 136-713, Republic of Korea

(2) Department of Radiation Plant Breeding and Genetics, Korea Atomic Energy Research Institute, Yuseong-Gu, Daejeon 305-600, Republic of Korea