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Evolutionary Developmental Biology (Evo-Devo)

Malcomber, Simon [1], Satoh-Nagasawa, Namiko [2], Nagasawa, Nobuhiro [3], Sakai, Hajime [3], Jackson, David [2].

Diversification of genes affecting inflorescence branching in grasses.

INFLORESCENCE branching is a major determinant of plant architecture and is used extensively to differentiate grass taxa. In maize, inflorescence branching is partially controlled by three genes: RAMOSA1 (RA1), RA2 and RA3. Double mutant analyses in maize indicate that RA2 and RA3 both function through the transcriptional regulation of RA1 in two separate genetic pathways. We have been focusing on the evolution of RA3 and related genes in grasses and grass relatives. Maize RA3 (ZmRA3) has been shown to encode a trehalose-6-phosphate phosphatase (TPP) gene that is expressed in discrete domains subtending the axillary meristems. Although maize has two RA3-like genes (RA3 and SISTER OF RA3 [SRA]), only one gene is present in a syntenous region of the rice genome. Phylogenetic analyses indicate that the rice RA3-like gene is co-orthologous to the maize SRA gene and that the gene duplication event producing the RA3 and SRA clades likely occurred near the base of the major diversification of the grass family (the BEP + PACCAD clade). The phylogenetic analysis thus indicates that rice has lost its copy of the RA3 co-ortholog. In situ hybridization analyses using the rice (Oryza sativa) SRA gene (OsSRA) detects gene expression in the primary and secondary branches, and near the base of the spikelet, suggesting that OsSRA might regulate inflorescence branching in rice. We present further details on the pattern of gene duplication within RAMOSA3-like genes in grasses and present additional analyses on the patterns on gene expression in diverse grass species.


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1 - California State University - Long Beach, Biological Sciences, 1250 Bellflower Blvd, Long Beach, California, 90840, USA
2 - Cold Spring Harbor Laboratory, 1 Bungtown Road, Cold Spring Harbor, New York, 11724, USA
3 - DuPont Crop Genetics, Experimental Station E353, Wilmington, Delaware, 19880, USA

Keywords:
grass
Poaceae
gene duplication
morphological evolution.

Presentation Type: Oral Paper:Papers for Topics
Session: 52-5
Location: 303/Bell Memorial Union
Date: Tuesday, August 1st, 2006
Time: 3:00 PM
Abstract ID:396


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