Abstract Detail

Evolutionary Developmental Biology (Evo-Devo)

Hope, Chelsea L. [1], Malcomber, Simon [2].

Phylogenomic analyses of the RAMOSA3 trehalose phosphate phosphatase lineage in grasses (Poaceae).

The degree of lateral branching plays a major role in determining the appearance of plants. The three RAMOSA genes, RAMOSA1 (RA1), RA2 and RA3, are responsible for the regulation of short branch (spikelet pair) meristems in maize. Ra3 encodes a trehalose phosphate phosphatase (TPP) that, along with Ra2, acts as an upstream regulator of Ra1. Maize has a second TPP gene roughly 10 kilobases upstream of RA3 called SISTER OF RAMOSA3 (SRA). The syntenic regions of rice and brachypodium, however, have only a single TPP gene that is most similar to ZmSRA. Phylogenetic analyses suggest the RA3/SRA duplication occurred prior to the major diversification of grasses, with a subsequent loss of RA3 orthologs near the base of the bamboo, rice and wheat lineage (BEP clade). In maize RA3 is expressed in a stripe between upper and lower florets and in a cup-shaped region at the base of spikelet pair meristems, but is not expressed as long branches initiate. ZmSRA expression is expressed generally throughout the plant with highest expression levels in roots. Expression analyses in other grasses suggest a complex pattern of evolution. SRA orthologs are expressed at the base of long branches in rice, barley and sorghum and at the base of long branches and the vasculature of teosinte. RA3 expression in sorghum and teosinte was detected at the base of short as well as long branches and between upper and lower florets. In Chasmanthium, ClRA3 expression was detected on the adaxial surface of all initiating and mature florets. Together these data suggest that the restricted pattern of RA3 expression subtending spikelet pair meristems does not coincide with the evolution of these structures in panicoid grasses, but rather appears to have occurred much more recently, potentially during the domestication of maize.

Broader Impacts:

1 - Cal State University Long Beach, 1250 Bellflower Blvd, Long Beach, Ca, 90840, USA
2 - Cal State University Long Beach, 1250 Bellflower Blvd. , Long Beach, Ca, 90840, USA

Keywords:
spikelet pair meristem
grasses
evo-devo
genome evolution
mRNA expression.

Presentation Type: Poster:Posters for Topics
Session: P
Location: Hall A/Convention Center
Date: Monday, August 2nd, 2010
Time: 5:30 PM
Number: PEV005
Abstract ID:635