“生長素極性輸送”是植物所有發(fā)育過程中的一個因素,，但關于這個因素是怎樣發(fā)揮作用的仍有很多東西需要了解,。在細胞中,，“生長素定向輸送”由PIN蛋白載體復合物控制?，F在，研究人員已經開發(fā)出一個新的計算模型,，來描述根系中細胞內和細胞間的擴散及由PIN幫助進行的生長素輸送,。該模型涉及植物發(fā)育的兩大問題。第一,，它支持關于生長素在引導根生長方面有一個最大值和一個梯度的概念,。第二,，它反映了一個分子何以能夠產生一系列信息：整個器官生長區(qū)的一個濃度梯度與生長素最大值密切相關。另一篇相關的論文表明,，４個PLETHORA基因是根發(fā)育所必不可少的,，是生長素梯度的候選輸出因子。
原始出處:
Nature 449, 1053-1057 (25 October 2007) | doi:10.1038/nature06206; Received 5 July 2007; Accepted 30 August 2007
PLETHORA proteins as dose-dependent master regulators of Arabidopsis root development
Carla Galinha1,2,3, Hugo Hofhuis1,2, Marijn Luijten1, Viola Willemsen1, Ikram Blilou1, Renze Heidstra1 & Ben Scheres1
Department of Biology, Faculty of Science, Utrecht University, Padualaan 8, 3584 CH Utrecht, The Netherlands
These authors contributed equally to this work.
Present address: Department of Plant Sciences, University of Oxford, South Parks Road, Oxford OX1 3RB, UK.
Correspondence to: Ben Scheres1 Correspondence and requests for materials should be addressed to B.S. (Email: [email protected]).
Factors with a graded distribution can program fields of cells in a dose-dependent manner1, 2, but no evidence has hitherto surfaced for such mechanisms in plants. In the Arabidopsis thaliana root, two PLETHORA (PLT) genes encoding AP2-domain transcription factors have been shown to maintain the activity of stem cells3. Here we show that a clade of four PLT homologues is necessary for root formation. Promoter activity and protein fusions of PLT homologues display gradient distributions with maxima in the stem cell area. PLT activities are largely additive and dosage dependent. High levels of PLT activity promote stem cell identity and maintenance; lower levels promote mitotic activity of stem cell daughters; and further reduction in levels is required for cell differentiation. Our findings indicate that PLT protein dosage is translated into distinct cellular responses.
