Supplementary Figure 1. A phylogram displaying the relationship of the homologs to other MYB proteins. The data indicates that OsMYB80 and TaMYB80 are closely related to GhMYB80, AtMYB80 and BnMYB80 than other MYB proteins. The tree distances in the phylogram are included in brackets. The phylogram was generated using VectorNTI software (Invitrogen) and peptide sequences obtained from TAIR and TIGR databases.

AtMYB80 (0.0321)

BnMYB80 (0.0308)

GhMYB80 (0.1860)

OsMYB80 (0.0838)

TaMYB80 (0.0791)

AtMYB35 (0.3191)

AtMYB4 (0.1944)

AtMYB32 (0.1934)

AtMYB41 (0.2087)

AtMYB74 (0.1371)

AtMYB102 (0.1546)

Os03g18480 (0.3100)

Os02g42870 (0.2969)

Os08g37970 (0.2996)

Os04g38740 (0.3109)

Os12g07640 (0.2380)

Supplementary Figure 2. Promoter sequence alignment of Arabidopsis, Canola, Rice and Wheat MYB80. The promoter sequences are immediately upstream of the ATG translational start site. The alignment was performed using MUSCLE (http://www.ebi.ac.uk/Tools/msa/muscle/). Blue represents high and purple represents moderate similarity, respectively. A highly conserved region is underlined in black.

Supplementary Figure 3. The AtMYB80 promoter contains a conserved region immediately upstream of the transcript start site. PLACE analysis identified four motifs which are conserved amongst the four species within this region. The motifs are underlined and coloured as follows, TGAC, W-BOX; GTGA and TCAC, GTGANTG10; ACCTACC, MYB4 (A/TACC MYB-core). The purple underlined sequence (CGTTGAATTCTTTA) is present in all four promoters with a highly conserved DOFCOREZM binding site (A/TAAAG) (orange). Motif analysis was performed using cis-PLACE (http://www.dna.affrc.go.jp/PLACE/).

GGAGTTGACCA.....TGGGTGACCTACCGG....ATCACA.....GTAGCGTTGAATTCTTTA -300bp

CTGCTCCTATATATGTACAGAATGTCGTCATATTATTGCCATGATACTTGGAACGGTGAAAGGAACCTGCTCTTGAATGAT

GTATAAATCAGAGAGAGAAAAAAAGACTGCTCAGTACTGTGTTTATCTATCAGCTTCGTAGAGCTCGGTATGCATCGATT

AATTGGTTTCAGGTCGCGTTGGCATTGAGCATGCGTAAGCCATGTATCTGCGTGGTTGATTTTACTGAAATGGTGGGAAA

AGAACATGATTCAGGGTGTTCTTGGAACTGGCAGCCGCTGGCCTTTGTGTTCTTGATGATAAGGATAGGGGAATAAAATA

GCATCCTCATATCAAGAGTGTAATCAACTAATCATAGTGCTGCAGCCCATAGAAATATGCATTCCCCTTGCTTGTAAAGAT

CCTACTAGGATAAAACTGTGTGCAGAAATGAATCGTTTATCTTTGACAGTTTTTTTTTTCTTTTTGAGTCTATCCTCCTGA

ACCTAAGGCTGTAAATTTGTTCGGACAAAGGATCATTACTCATAGCCTGCTATGTTCACAAGGTTTTATATTACTGAATAG

TGGTGTTTCATCAAGCAGCATTAGTGAATAGTTGCAGTGGCAGAGTGGTGCAGGGCGTCAGTGAGCGAGATGGCGAGG

CGAGAACGCGAGCGGCGCCGGGAGCGCGCGGGGCTTGGACCGTGGCCGTGAGGGGGGTTGACCCGGCGCTGCGCGGG

TGGGCAACCTGTCCCGCCCCCCCGGGGGGAGGCTCACGCGTTGCGCGGGCGTTGAATTCTTTATGCCGCCCATGCCGC

CTTCGCCCCCCGTGCGCGCGCGCGCGCGCCCACTCGCCGGCGCGGCAGCGCGCGCGCGCGCGCGCGGGCGGTCGCGA

GGCCGCGAGCCTATTTATAACACGCGGCGCGGCCGTGTGAGCGCCGCACGCACGCAGCAGCAGCGGAATCTCGACGG

CGGCGACATCATG

Supplementary Figure 4. Sequence analysis of the OsMYB80 promoter deletion constructs. The promoter deletions occurred at -168 bp (highlighted in grey) for the construct pOS-168 while pOS-328 occurred at -328 bp and also included the conserved region (highlighted in green). The putative TATA box is bold and underlined (black), a putative Initiator (Inr) motif is bold and underlined (blue), upstream motifs are highlighted red (DOFCOREZM) and yellow (GTGANTG10). Motif analysis was performed using cis-PLACE (http://www.dna.affrc.go.jp/PLACE/).

Supplementary Figure 5. The conserved amino acid sequence downstream of the MYB domain forms two α-helical structures (underlined). The sequence analysis was performed using NPS@: Network Protein Sequence Analysis (http://npsa-pbil.ibcp.fr/cgi-bin/npsa_automat.pl?page=/ NPSA/npsa_server.html).

IDPVTHKPFSHLMAEITTTLNPPQVSHLAEAALGCFKDEMLHLLTKKRV

Primer Purpose (V = vector construction) Sequence 5’ to 3’AD TaMYB80 Genomic walk (GW) Adapter primer GTAATACGATCACTATAGGGCNAD TaMYB80 GW Nested adapter primer ACTATAGGGCACGCGTGGTTa+245R TaMYB80 GW gene specific R TCTTCCCGCAGCGCTGCAGCCCTGTCATa+225R TaMYB80 GW nested gene specific R CTGTCACGCGCGGCAACCTCGTTCAGCTa+138R TaMYB80 GW nested gene specific R ACTCACCGGCGTTCTTGGGGATGAGGCOsP-1021F OsMYB80 pro:GUS & complementation F V CACAAGCTTGTCAGAGGGTGGTGGCACTCTOsP-ATG OsMYB80 pro:GUS R V TTGGATCCCATGATGTCGCCGCCGTCGAGATTCOsP-168R OsMYB80 pro:GUS -168 truncation R V GTTGGATCCCATGGGCGGCATAAAGAATTCAACOsP-328R OsMYB80 pro:GUS -328 truncation R V GTTGGATCCCTCGCTCACTGACGCCCTGCACCATaP-F TaMYB80 pro:GUS F V CACCGGCCCCTGCAAAACTCCCGCATaP-R TaMYB80 pro:GUS F V GTCGGCGCGTCCGCCTCCGAGGCOTi2+344F Os/TaMYB80 intron spanning RT-PCR F TCGTCGGCAACAGGTGGTCGGTGATCGOTx3+816R Os/TaMYB80 3rd exon RT-PCR R CTTGATGCGCTCGATGGTGTCGTCTaBtubF Wheat β-tubulin RT-PCR F AGGTCTCCACCTCTGTTGTTTaBtubR Wheat β-tubulin RT-PCR R AGCCATACAACAGTGTCCTGAtPF-Bam AtMYB80 promoter complementation F V ATATCGGATCCAAGCCTTAGATAACTATTACAGAGAAtPR-H3 AtMYB80 promoter complementation R V TTAAAAGCTTTTCTTCTTTCTTTCTTTCTAGTaATG-F TaMYB80 gene complementation F V ATAAAAGCTTATGGGCCGGATCCCTTGCTGCGATaCode-R TaMYB80 gene complementation R V ATTAACTAGTTTAGTCACACATGTTATTCGTOsATG-F OsMYB80 gene complementation F V TATTAAGCTTATGGGGCGGGTGCCGTGCTGCGAOsCode-R OsMYB80 gene complementation R V ATTAACTAGTCTACACCATGTGATTCGTGAGTaPF-Bam TaMYB80 promoter complementation F V ATATGGATCCGGCCCCTGCAAAACTCCCGCATaPR-H3 TaMYB80 promoter complementation R V AATAAAGCTTGTCGGCGCGTCCGCCTCCGAGGOsPR-H3 OsMYB80 promoter complementation R V ATATAAGCTTGATGTCGCCGCCGTCGAGATTCCGBnPF BnMYB80 promoter complementation F V AATTGGATCCCGTGGGGGTCCTGTAATTGBnCR BnMYB80 gene complementation & RT-PCR R AATTAAGCTTTCAAACCACATGATTAATGAGBnx2+F BnMYB80 2nd exon RT-PCR F GTGGACAAACTATTTGCGTCCTGACCBnEAR-R BnMYB80:EAR fusion R V ACTAGTTTACGCAAATCCTAGTCTGAGCTCGAGGTCCAAA

TCTAAACCAACCACATGATTAATGAGATCAtBnx2F At/BnMYB80 2nd exon RT-PCR F GTCAAGTTTCACTCTGTTCTTGGTAt80-R AtMYB80 RT-PCR R TCAAACCATATGATTGATGAGATCAEAR-R EAR RT-PCR R, used in all EAR-related exp. ATCCTAGTCTGAGCTCGAGGTCβ-Tub F2 β-tubulin RT-PCR F GGACACTACACTGAAGGTGCTGAGβ-Tub R3 β-tubulin RT-PCR R GGCTCTGTATTGCTGTGATCCACGBnAct7-F BnActin 7 RT-qPCR F TCCCTCAGCACTTTCCAACAGBnAct7-R BnActin 7 RT-qPCR R ACACTCACCACCACGACCCAGqBn80F BnMYB80 RT-qPCR F TGGCAGAGATAACCACTACACTCqBn80R BnMYB80 RT-qPCR R GTGATCCAAAATGAATCAAACCACqEAR-R BnMYB80:EAR RT-qPCR R TCCTAGTCTGAGCTCGAGGTCCR2R3+44R Truncated MYB80:EAR fusion R V TTAATAAGCTTACGCAAATCCTAGTCTGAGCTCGAGGTCC

AAATCTAAACCCTTGTGGGTCACCGGATCTATTR2R3-R Truncated MYB80:EAR fusion R V TTAATAAGCTTACGCAAATCCTAGTCTGAGCTCGAGGTCC

AAATCTAAACCAACACGTTTCTTGGTGAGCAAGAt+46F AtMYB80 +46bp RT-PCR F CAATGGACTCCTGAAGAAGACAAC

Supplemental Table 1. Primers used in this article are listed below in the order that they were used according to the figures presented.