Plant Physiol, March 2002, Vol. 128, pp. 1077-1086
Members of the c1/pl1 Regulatory Gene
Family Mediate the Response of Maize Aleurone and Mesocotyl to
Different Light Qualities and Cytokinins1
Paolo
Piazza,2
Antonia
Procissi,2
Gareth I.
Jenkins, and
Chiara
Tonelli*
Dipartimento di Genetica e di Biologia dei Microrganismi,
Via Celoria, 26, 20133 Milano, Italy (P.P., A.P., C.T.); and Plant
Molecular Science Group, Division of Biochemistry and Molecular
Biology, Institute of Biomedical and Life Sciences, Bower Building,
University of Glasgow, Glasgow G12 8QQ, United Kingdom (G.I.J.)
We investigated the role of transcription factors (R, SN,
C1, and PL) in the regulation of anthocyanin biosynthesis by different light qualities (white, red, blue, and ultraviolet) and by cytokinin in
maize (Zea mays). We analyzed anthocyanin accumulation,
structural gene expression, and regulatory gene expression in the seed
aleurone and the seedling mesocotyl. In the mesocotyl, white, blue, and ultraviolet-B light strongly induced anthocyanin accumulation and
expression of two key structural genes. In contrast, red light had
little effect. Cytokinin enhanced the response to light but was not
sufficient to induce anthocyanin accumulation in darkness. Plants with
the pl-bol3 allele showed high levels of
anthocyanin accumulation in response to light, whereas those with the
pl-W22 allele did not, demonstrating the
importance of pl1 in the light response. The expression
of the pl-bol3 gene, encoding an
MYB-related transcription factor, was induced by light and
enhanced by cytokinin in a very similar manner to the structural genes
and anthocyanin accumulation. Expression of the bHLH
(basic helix-loop-helix) Sn1-bol3 gene
was stimulated by several light qualities, but not enhanced by
cytokinin, and was less well correlated with the induction of
anthocyanin biosynthesis. In the aleurone, white, red, and blue light
were effective in stimulating anthocyanin accumulation and expression
of the MYB-related gene C1. The
bHLH R gene was constitutively expressed. We conclude
that specific members of the MYB-related
c1/pl1 gene family play important roles
in the regulation of anthocyanin synthesis in maize in response to
different light qualities and cytokinin.
1
This work was supported by Ministero
Delle Politiche Agricole E Forestali Progetto Biotecnologie Vegetali
(Area 1, Progetto N. 2) and by Ministero Dell' Istruzione, Dell'
Università E Della Ricerca (Italy) Progetto Strategico
Biotecnologie (to C.T.).
2
These authors contributed equally to the paper.
*
Corresponding author; e-mail chiara.tonelli{at}unimi.it; fax
39-02-5835-5044.
© 2002 American Society of Plant Physiologists
