Cytokinin receptors are required for normal development of auxin-transporting vascular tissues in the hypocotyl but not in adventitious roots
Cytokinin receptors are required for normal development of auxin-transporting vascular tissues in the hypocotyl but not in adventitious roots
复制标题
细胞分裂素受体是下胚轴正常发育输送辅助素的维管组织所必需的，但不是不定根所必需的
DOI：
10.1093/pcp/pci240
复制
发表时间：
2006-02-01
影响因子：
4.9
通讯作者：
Satoh, S
中科院分区：
文献类型：
--
作者：
Kuroha, T;Ueguchi, C;Satoh, S
植物通过调节胚后根（侧根和不定根）的形成和生长来改变其根系的结构以适应环境。为了更好地了解这种调节的遗传基础，我们筛选了甲基磺酸乙酯诱变的拟南芥不定根突变株系。一个突变体表现出主根生长迟缓，侧根不产生，不定根形成增强。定位和遗传互补表明，这个突变体命名为wool-3，是拟南芥组氨酸激酶4（AHK 4）的一个等位基因，AHK 4是一个已知编码细胞分裂素受体的焦点。wol-3突变体的初生根和下胚轴的维管系统虽然丧失，但不定根的维管系统发育正常。在wol-3突变体的下胚轴中，生长素信号聚集在败育的维管系统周围。在wol-3突变体的初生根上施用生长素可诱导侧根的形成。在wol-3中，放射性标记的生长素从下胚轴顶端向主根的运输受到抑制。虽然只有一个单一的氨基酸改变发生在AHK 4，根的形态在wol-3突变体是非常相似的ahk 2 ahk 3 ahk 4三重突变体，这是一个功能丧失的突变体的三个细胞分裂素受体。这意味着AHK 4的功能障碍会影响其他受体的功能。我们的研究结果表明，细胞分裂素受体是必要的生长素运输维管组织在下胚轴的形成，而不是在不定根。
Plants alter the architecture of their root systems to adapt to the environment by modulating post-embryonic (lateral and adventitious) root formation and growth. To understand better the genetic basis of this regulation, we screened ethylmethane sulfonate-mutagenized lines of Arabidopsis thaliana for adventitious rooting mutants. One mutant showed retardation of the primary root growth, no production of lateral roots and enhanced formation of adventitious roots. Mapping and genetic complementation revealed that this mutant named wooden leg-3 (wol-3) was an allele of ARABIDOPSIS HISTIDINE KINASE 4 (AHK4), a focus known to encode a cytokinin receptor. Although the vascular system of the primary root and hypocotyl in the wol-3 mutant was aborted, that of the adventitious roots was normally developed. In the hypocotyl of the wol-3 mutant, auxin signals accumulated around the aborted vascular system. The application of auxin to primary roots induced lateral root formation in the wol-3 mutant. Transport of radiolabeled auxin from the top of the hypocotyl to the primary root was inhibited in wol-3. Although only a single amino acid alteration had occurred in AHK4, the root morphology in the wol-3 mutant was quite similar to that in the ahk2 ahk3 ahk4 triple mutant, which is a loss-of-function mutant of the three cytokinin receptors. This implies that the functional disturbance of AHK4 affects the function of the other receptors. Our results suggest that cytokinin receptors are necessary for the formation of auxin-transporting vascular tissues in the hypocotyl, but not in adventitious roots.