Nebularine Affects Plant Growth and Development but does not Interfere with Cytokinin Signaling
Nebularine Affects Plant Growth and Development but does not Interfere with Cytokinin Signaling
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Nebularine 影响植物生长和发育，但不干扰细胞分裂素信号传导
DOI：
10.1007/s00344-009-9096-5
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发表时间：
2009
影响因子：
4.8
通讯作者：
I. Frébort
中科院分区：
文献类型：
--
作者：
H. Pospíšilová;J. Nisler;L. Spíchal;I. Frébort
众所周知，在动物中，Nebularine具有高细胞毒性，而在植物中，它最初被认为是一种抗细胞分裂素。在这项研究中，我们表明，在经典的细胞分裂素的生物测定，星云素拮抗细胞分裂素功能的衰老和愈伤组织的生物测试，但不是在苋属生物测定。星云碱逆转了细胞分裂素对拟南芥幼苗侧根形成的抑制作用，单独应用时引起侧根形成增加和主根缩短。系统地喷洒拟南芥植物与星云素导致变黄和紫色色素的形成，局部干燥和枯萎，虽然年轻的植物表现出更大的弹性。在植物和动物细胞中的星云碱细胞毒性的比较表明，烟草BY-2细胞的生长受到抑制，其效力仅比哺乳动物细胞系低约10倍。最重要的是，与拟南芥细胞分裂素受体AHK 3和CRE 1/AHK 4的直接结合试验表明，星云碱不与天然细胞分裂素反式玉米素竞争结合。虽然nebularine减少细胞分裂素诱导的细胞分裂素报告ARR 5：GUS在植物中的表达，同样的效果观察到DR 5：GUS，生长素报告基因。两者合计，结果表明，星云碱的作用模式不涉及细胞分裂素信号传导，而抗细胞分裂素样作用是抑制动物系统中描述的各种过程的结果。
Nebularine is known for its high cytotoxicity in animals, whereas in plants it was originally believed to be an anticytokinin. In this study we show that in classical cytokinin bioassays, nebularine antagonized cytokinin function in senescence and callus biotests but not in the Amaranthus bioassay. Nebularine reversed the inhibitory effect of cytokinin on lateral root formation in Arabidopsis seedlings, and when applied alone caused increased lateral root formation and shortening of the main root. Systematic spraying of Arabidopsis plants with nebularine led to yellowing and formation of purple pigments, local drying, and withering, although younger plants showed a greater resilience. Comparison of nebularine cytotoxicity in plant and animal cells showed that the growth of tobacco BY-2 cells was inhibited with only about tenfold lower efficacy than mammalian cell lines. Most importantly, direct binding assay with Arabidopsis cytokinin receptors AHK3 and CRE1/AHK4 showed that nebularine did not compete for binding with the natural cytokinin trans-zeatin. Although nebularine reduced cytokinin-induced expression of the cytokinin reporter ARR5:GUS in planta, the same effect was observed for DR5:GUS, an auxin reporter gene. Taken together, the results indicate that the mode of action of nebularine does not involve cytokinin signaling and that the anticytokinin-like effect is rather a consequence of the inhibition of various processes as described for animal systems.