IBIS-Flora

Angiosperm Flora of India

Expression of "SHOOT MERISTEMLESS, WUSCHEL", and "ASYMMETRIC LEAVES1" Homologs in the Shoots of Podostemaceae: Implications for the Evolution of Novel Shoot Organogenesis

Publication Type:Journal Article
Year of Publication:2010
Authors:Katayama, N, KOI, SATOSHI, KATO, MASAHIRO
Journal:The Plant Cell
Volume:22
Issue:7
Date Published:2010
ISBN Number:10404651
Keywords:Podostemaceae
Abstract:

Podostemaceae (the river weeds) are ecologically and morphologically unusual angiosperms. The subfamily Tristichoideae has typical shoot apical meristems (SAMs) that produce leaves, but Podostemoideae is devoid of SAMs and new leaves arise below the base of older leaves. To reveal the genetic basis for the evolution of novel shoot organogenesis in Podostemaceae, we examined the expression patterns of key regulatory genes for shoot development (i.e., SHOOT MERISTEMLESS (STM), WUSCHEL (WUS), and ASYMMETRIC LEAVES1/ROUGH SHEATH2/PHANTASTICA (ARP) orthologs) in Tristichoideae and Podostemoideae. In the SAM-mediated shoots of Tristichoideae, like in model plants, STM and WUS orthologs were expressed in the SAM. In the SAM-less shoots of Podostemoideae, STM and WUS orthologs were expressed in the initiating leaf/bract primordium. In older leaf/bract primordia, WUS expression disappeared and STM expression became restricted to the basal part, whereas ARP was expressed in the distal part in a complementary pattern to STM expression. In the reproductive shoots of Podostemoideae with a normal mode of flower development, STM and WUS were expressed in the floral meristem, but not in the floral organs, similar to the pattern in model plants. These results suggest that the leaf/bract of Podostemoideae is initiated as a SAM and differentiates into a single apical leaf/bract, resulting in the evolution of novel shoot-leaf mixed organs in Podostemaceae.

URL:http://www.jstor.org/stable/20780555
Short Title:The Plant Cell
Taxonomic name: 
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Scratchpads developed and conceived by (alphabetical): Ed Baker, Katherine Bouton Alice Heaton Dimitris Koureas, Laurence Livermore, Dave Roberts, Simon Rycroft, Ben Scott, Vince Smith