Leukamenin E调节拟南芥幼苗生长发育的模式及其机制

The pattern and mechanism of seedling growth and development regulated by Leukamenin E in Arabidopsis thaliana

研究对映-贝壳杉烷型二萜化合物Leukamenin E对拟南芥种子萌发、下胚轴伸长以及根生长发育的作用模式,并探讨植物激素生长素和乙烯可能介导Leukamenin E影响拟南芥主根生长、侧根和根毛发育的初步机制。结果表明:Leukamenin E浓度在10~160μmol·L^(-1)范围对拟南芥种子的萌发率无显著影响,但高浓度Leukamenin E(80~160μmol·L-1)显著抑制种子的萌发速率。Leukamenin E对拟南芥幼苗根生长的抑制作用明显高于对下胚轴的抑制效应。进一步研究表明,Leukamenin E通过阻滞根尖细胞有丝分裂和细胞伸长进而抑制主根的生长,并能促进侧根提前发生并影响其形成数量,同时减少根毛密度及降低根毛长度。Leukamenin E联合乙烯利(乙烯释放剂)处理可阻止乙烯利单独使用对拟南芥幼苗根毛生长的促进作用,与Ag+(乙烯竞争抑制剂)联合乙烯利的作用效果相一致,表明Leukamenin E可能通过干扰根细胞乙烯途径而抑制根毛发育。流动注射化学发光分析和酶联免疫检测的结果发现,Leukamenin E显著上调拟南芥幼苗根组织中生长素(IAA)水平,表明生长素可能作为主要因子介导了Leukamenin E对拟南芥幼苗根生长发育的调节作用。

This paper studied the pattern of the Leukamenin E, an ent-kaurene diterpenoid regu- lation on the seed germination, hypocotyl elongation, and root growth and development in Arabidopsis thaliana. In addition, this work also discussed the mechanism of primary root growth, lat- eral root and root hair development regulated by Leukamenin E possibly through the phytohormone auxin and ethylene pathway in A. thaliana. The results showed that within 10-160 ·L^-1, Leukamenin E had no obvious effect on seed germination rate ; however, higher levels of Leukamenin E （80-160 ·L^-1） significantly reduced the seed germination speed. The inhibiting effect of Leukamenin E on root growth was more obvious than on hypocotyl elongation. Furthermore, Leukamenin E inhibited the primary tion. Leukamenin E accelerated the lateral root growth through reducing cell mitosis and elongaroot initiation and affected the lateral root numbers, and also reduced the root hair density and shortened the root hair length. Promoting root hair growth was stimulated by exogenous ethephon, an ethylene-releasing agent, and could be re- versed by Leukamenin E treatment, which is similar to the effect of the Ag^＋, an ethylene action inhibitor. These results strongly suggested that the inhibition of Leukamenin E on root hair growth may depend on the ethylene pathway. Leukamenin E markedly increased the IAA level in root, which was detected by using the flow injection chemiluminescence method and the enzyme-linked immunosorbent assays, indicating that auxin may play an important role in regulation of root growth by Leukamenin E in A. thaliana.