Hoshino Tomoki, Miyamoto Kensuke, Ueda Junichi
Graduate School of Science, Osaka Prefecture University, Sakai, Osaka, Japan.
Biol Sci Space. 2004 Nov;18(3):94-5.
On STS-95 space experiment, etiolated pea (Pisum sativum L. cv. Alaska) seedlings showed automorphosis and activities of auxin polar transport in epicotyls were substantially suppressed. These results together with the fact that inhibitors of auxin polar transport induced automorphosis-like growth and development strongly suggested that there are close relationships between automorphosis and auxin polar transport in etiolated pea seedlings. In order to know how gravistimuli control auxin polar transport at molecular levels, we isolated novel cDNAs of PsPIN2 and PsAUX1 encoding putative auxin efflux and influx carriers from etiolated pea seedlings. Significantly high levels in homology were found on nucleotide and deduced amino acid sequences among PsPIN2, PsPIN1 (accession no. AY222857) and AtPINs, and between PsAUX1 and AtAUX1. Exogenously applied auxin substantially enhanced the expression of PsAUX1 and PsPIN2 as well as PsPIN1. Simulated microgravity conditions on a 3-dimensional clinostat remarkably increased gene expression of PsPIN1 and PsAUX1 in the hook and the 1st internode of pea epicotyls, while the increase of expression of PsPIN2 in both organs was not so much. These results suggest that PsPINs and PsAUX1 are auxin-inducible genes, and the expression of PsPINs and PsAUX1 is under the control of gravistimulation. A possible role of these genes in regulating auxin transport relevant to automorphosis of etiolated pea seedlings is also discussed.
在STS - 95太空实验中，黄化豌豆（豌豆品种阿拉斯加）幼苗出现自疏现象，并且上胚轴中生长素极性运输的活性被大幅抑制。这些结果以及生长素极性运输抑制剂诱导类似自疏的生长发育这一事实，强烈表明在黄化豌豆幼苗中，自疏与生长素极性运输之间存在密切关系。为了了解重力刺激如何在分子水平上控制生长素极性运输，我们从黄化豌豆幼苗中分离出了编码假定生长素外排和内流载体的PsPIN2和PsAUX1的新cDNA。在PsPIN2、PsPIN1（登录号AY222857）和AtPINs之间，以及在PsAUX1和AtAUX1之间，核苷酸和推导的氨基酸序列具有显著的高度同源性。外源施加生长素显著增强了PsAUX1、PsPIN2以及PsPIN1的表达。在三维回转器上模拟微重力条件显著增加了豌豆上胚轴弯钩和第一节间中PsPIN1和PsAUX1的基因表达，而两个器官中PsPIN2表达的增加幅度则没那么大。这些结果表明，PsPINs和PsAUX1是生长素诱导型基因，并且PsPINs和PsAUX1的表达受重力刺激的控制。还讨论了这些基因在调节与黄化豌豆幼苗自疏相关的生长素运输中的可能作用。
