Structure and Expression of Maize Phytochrome Family HomeologsSequence data from this article have been deposited with the EMBL/GenBank Data Libraries under accession nos. AY234825, AY234826, AY234827, AY234828, AY234829, AY234830.

Abstract

To begin the study of phytochrome signaling in maize, we have cloned and characterized the phytochrome gene family from the inbred B73. Through DNA gel blot analysis of maize genomic DNA and BAC library screens, we show that the PhyA, PhyB, and PhyC genes are each duplicated once in the genome of maize. Each gene pair was positioned to homeologous regions of the genome using recombinant inbred mapping populations. These results strongly suggest that the duplication of the phytochrome gene family in maize arose as a consequence of an ancient tetraploidization in the maize ancestral lineage. Furthermore, sequencing of Phy genes directly from BAC clones indicates that there are six functional phytochrome genes in maize. Through Northern gel blot analysis and a semiquantitative reverse transcriptase polymerase chain reaction assay, we determined that all six phytochrome genes are transcribed in several seedling tissues. However, expression from PhyA1, PhyB1, and PhyC1 predominate in all seedling tissues examined. Dark-grown seedlings express higher levels of PhyA and PhyB than do light-grown plants but PhyC genes are expressed at similar levels under light and dark growth conditions. These results are discussed in relation to phytochrome gene regulation in model eudicots and monocots and in light of current genome sequencing efforts in maize.

Suppression of β-catenin and Cyclooxygenase-2 Expression and Cell Proliferation in Azoxymethane-Induced Colonic Cancer in Rats by Rice Bran Phytic Acid (PA)

“…We have found that Ki-67 score has a significantly positive relationship with total COX-2 expression. Study by Sheehan et al (2004) which is consistent with our finding demonstrated that COX-2 expression may contribute to colonic tumourigenesis by promoting cell growth, new vessel formation, invasiveness and, in particular, metastatic potential. Ki-67 also has positive linear relationship with ß-catenin expression.…”

Ac-Immobilized, a Stable Source of Activator Transposase That Mediates Sporophytic and Gametophytic Excision of Dissociation Elements in Maize

“…Radiolabeled Ds6-like and R1 gene probes were generated and purified as described (Sheehan et al 2004). Hybridizations were performed as described (Church and Gilbert 1984) at 65°in a bottle incubator (Thermo Hybaid, Needham Heights, MA).…”

Phytochromes and Phytochrome Interacting Factors

“…Phytochromes in rice (Oryza sativa) are present as single-copy genes . However, in maize (Zea mays), due to the gene duplication from the ancient tetraploidization in the maize ancestral lineage, phytochrome genes are present as homolog pairs for each of the three genes, known as phyA1 and phyA2, phyB1 and phyB2, and phyC1 and phyC2 (Sheehan et al, 2004). Sharing three classes of phytochromes (phyA/B/C) and missing two counterparts (phyD/E) in monocots suggest unique roles of phyD/E in dicots and also highlight the fundamental differences between the monocot and dicot phytochrome signaling pathways.…”