Pia G. Sappl （School of Biological Sciences, Monash University, Melbourne, Victoria 3800, Australia）

2010年06月15日(火) 11:00 より 12:00 まで

明大寺地区１階会議室（１１１）

ＥＲＡＴＯ長谷部分化全能性進化プロジェクト 榊原 恵子 内線7600

In seed plants, leaves are born on radial shoots but unlike shoots they are determinate dorsiventral organs made of flat lamina. YABBY genes are found only in seed plants and in all cases studied, are expressed primarily in lateral organs and in a polar manner. Despite their simple expression patterns, Arabidopsis plants lacking all YABBY gene activities have a wide range of morphological defects in all lateral organs as well as the shoot apical meristem (SAM). Here we show that leaves lacking all YABBY activities are initiated as dorsiventral appendages but fail to properly activate lamina programs. In particular, a marginal leaf domain is not established, the activation of most CINCINATTA class TCP genes (CIN-TCPs) does not commence, and SAM-specific programs are reactivated. Altered distribution of auxin signaling and the auxin efflux carrier PIN1, highly reduced venation, initiation of multiple cotyledons, and gradual loss of the SAM accompany these defects. We suggest that YABBY functions were recruited to mould modified shoot systems into flat plant appendages by translating organ polarity into lamina specific programs that include marginal auxin flow and activation a maturation schedule directing determinate growth.

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