Arabidopsis KNOXI proteins activate cytokinin biosynthesis

被引:433
作者
Yanai, O
Shani, E
Dolezal, K
Tarkowski, P
Sablowski, R
Sandberg, G
Samach, A
Ori, N
机构
[1] Hebrew Univ Jerusalem, Robert H Smith Inst Plant Sci & Genet Agr, Fac Agr Food & Environm Qual Sci, IL-76100 Rehovot, Israel
[2] Palacky Univ, Lab Growth Regulators, Olomouc 78371, Czech Republic
[3] ASCR, Inst Expt Bot, Olomouc 78371, Czech Republic
[4] Swedish Univ Agr Sci, Umea Plant Sci Ctr, S-90183 Umea, Sweden
[5] John Innes Ctr, Dept Cell & Dev Biol, Norwich NR4 7UH, Norfolk, England
基金
英国生物技术与生命科学研究理事会;
关键词
D O I
10.1016/j.cub.2005.07.060
中图分类号
Q5 [生物化学]; Q7 [分子生物学];
学科分类号
071010 ; 081704 ;
摘要
Plant architecture is shaped through the continuous formation of organs by meristems [1]. Class I KNOTTED1-like homeobox (KNOXI) genes are expressed in the shoot apical meristem (SAM) and are required for SAM maintenance [2-6]. KNOXI proteins and cytokinin, a plant hormone intimately associated with the regulation of cell division [7, 8], share overlapping roles, such as meristem maintenance and repression of senescence [2, 9-11], but their mechanistic and hierarchical relationship have yet to be defined. Here, we show that activation of three different KNOXI proteins using an inducible system resulted in a rapid increase in mRNA levels of the cytokinin biosynthesis gene isopentenyl transferase 7 (AtlPT7) and in the activation of ARR5, a cytokinin response factor. We further demonstrate a rapid and dramatic increase in cytokinin levels following activation of the KNOXI protein SHOOT MERISTEMLESS (STM). Application of exogenous cytokinin or expression of a cytokinin biosynthesis gene through the STM promoter partially rescued the stm mutant. We conclude that activation of cytokinin biosynthesis mediates KNOXI function in meristem maintenance. KNOXI proteins emerge as central regulators of hormone levels in plant meristems.
引用
收藏
页码:1566 / 1571
页数:6
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