生长素参与三十烷醇诱导的拟南芥侧根发育

[目的]本文旨在研究植物生长调节剂三十烷醇对拟南芥侧根发育的影响，揭示其调控侧根发育的机制，为生产上的使用提供理论依据。[方法]以野生型拟南芥、生长素不敏感型突变体为试验材料，外源三十烷醇处理生长5 d的幼苗，分析侧根数目、侧根密度、侧根原基数量、侧根原基密度、细胞周期调控的关键基因的表达、根部内源吲哚乙酸（indole-3-acetic acid，IAA）含量、生长素合成关键基因表达等指标。[结果]外源三十烷醇处理拟南芥的幼苗，能够诱导侧根的产生，0.20、0.50和1.00 μmol？L-1三十烷醇处理8 d，侧根密度分别增加了59.0%、97.9%和54.2%；0.5 μmol？L-1三十烷醇处理后阶段A的侧根（此时包含3层细胞）原基密度增加了67.8%。外源三十烷醇处理增加根部IAA的含量，上调参与生长素合成的关键酶基因表达，增强根尖和不同发育阶段侧根生长素响应报告基因DR5∶β-glucuronidase（GUS）和IAA2∶GUS的表达。生长素运输抑制剂三碘苯甲酸（2，3，5-triiodobenzoic acid，TIBA）及萘基邻氨甲酰苯甲酸（1-naphthylphthalamic acid，NPA）和作用抑制剂p-chlorophenoxy isobutyric acid（PCIB）的添加抑制了三十烷醇诱导的侧根发育；生长素不敏感型突变体tir1-1和axr1-3对三十烷醇缺乏响应，而aux1-7和eir1-1对三十烷醇的响应弱于野生型。[结论]三十烷醇能够通过促进侧根原基的从头形成来增加侧根的密度，其诱导侧根发育依赖生长素的途径。
[Objectives] The aim of the paper is to explore the possible mechanism of triacontanol(TRIA)in the regulation of lateral root(LR)development, and to provide theoretical basis for the practice. [Methods] Using wild type(WT), auxin-insensitive mutant seedlings as materials, the 5-day-old seedlings were treated with different concentrations of TRIA and the effect of TRIA on LR formation was analyzed. [Results] TRIA treatment induced LR formation markedly, and the increase in the LR density was positively correlated with TRIA concentration. After treatment with 0.20, 0.50, and 1.00 μmol？L-1 TRIA for 8 d, the density of LR increased by 59.0%, 97.9% and 54.2%, respectively. The density of stage A lateral root primordium increased by 67.8% under 0.5 μmol？L-1 TRIA treatment compared with the control. TRIA application significantly increased the indole-3-acetic acid(IAA)level, transcript levels of many IAA biosynthesis genes and the expression levels of DR5:GUS and IAA2:GUS in root. Auxin transport inhibitors 2, 3, 5-triiodobenzoic acid(TIBA)and 1-naphthylphthalamic acid(NPA), and the auxin action inhibitor p-chlorophenoxy isobutyric acid(PCIB)each inhibited TRIA-mediated LR formation dramatically in WT seedlings. Further genetic studies revealed that LR formation in tir1-1 and axr1-3 mutants was insensitive to TRIA treatment, but LR formation was less sensitive in aux1-7 and eir1-1 mutants than in WT plants. [Conclusions] Our results showed that TRIA treatment promoted LR formation by inducing de novo formation of lateral root primordium(LRP)in Arabidopsis seedlings and auxin-dependent pathway participated in the regulation of LR formation when Arabidopsis seedlings were subjected to exogenous TRIA application