3,4-二羟基苯乙酮胁迫对天山云杉种子萌发过程中内源植物激素含量变化的影响

3,4-二羟基苯乙酮(DHAP)是天山云杉(Picea schrenkiana ssp. tianschanica)叶和凋落物中存在的主要自毒物质, 是导致天山云杉林天然更新障碍的原因之一。为了解释自毒物质发生作用的生理机制, 该文设计多个浓度梯度的DHAP溶液处理天山云杉种子, 以发芽率和发芽势为种子萌发参数, 运用反相超高效液相色谱(UPLC)分析技术, 检测了种子萌发过程中内源植物激素玉米素(ZT)、赤霉素(GA₃)、吲哚乙酸(IAA)和脱落酸(ABA)含量水平的变化。研究结果表明: DHAP处理对天山云杉种子萌发影响具有浓度效应, 表现为5.0 mmol·L^-1 > 0.1 mmol·L^-1 > 1.0 mmol·L^-1 >对照, 即5.0 mmol·L^-1 DHAP处理组对种子萌发的抑制作用最强、0.1 mmol·L^-1 DHAP处理组次之、1.0 mmol·L^-1 DHAP处理组最弱; DHAP处理组的种子内源ZT、GA₃浓度水平降低, ABA含量升高, GA₃浓度峰值出现时间延迟, IAA浓度在高浓度(5.0 mmol·L^-1 DHAP)处理组短时间内(3-6天)过量积累, 1.0和5.0 mmol·L^-1 DHAP处理组的种子内源ABA浓度峰值出现时间延迟; DHAP处理种子萌发1-6天时, ZT/(GA₃+IAA)比值降低, IAA/ZT、ABA/ZT比值增大; ABA/(ZT + GA₃ + IAA)比值在0.1 mmol·L^-1 DHAP处理组增大, 在5.0 mmol·L^-1 DHAP处理组降低。DHAP处理引发种子内源激素含量水平及激素含量间比值变化, 可能是抑制、延迟天山云杉种子萌发的主要原因。

Effects of 3,4-dihydroxy acetophenone stress on changes in the content of endogenous plant hormones during seed germination in Picea schrenkiana ssp. tianschanica

Aims Picea schrenkiana ssp. tianschanica is a major tree species in forest ecosystems in the Xinjiang Uygur Autonomous Region, West China, and plays an important role in the regional water conservation. 3,4-dihydroxy acetophenone (DHAP) is a principal autotoxic substance occurring in foliage and litter of P. schrenkiana ssp. tianschanica that causes suppressed natural regeneration in P. schrenkiana ssp. tianschanica forests. The objectives of this study were to investigate changes in the content of endogenous plant hormones during seed germination in P. schrenkiana ssp. tianschanica as affected by DHAP, and to elucidate the underlying physiological mechanisms in the autotoxic effects.
Methods We investigated the inter-relationships among DHAP treatment, seed germination, and changes in the concentration of endogenous plant hormones by measuring the contents of zeatin (ZT), gibberellin (GA3), indole-acetic acid (IAA), and abscisic acid (ABA) during germination process in P. schrenkiana ssp. tianschanica seeds with or without DHAP treatment. The concentrations of plant hormones in germinating seeds were measured with the method of ultra performance liquid chromatography (UPLC).
Important findings Results showed that the impact of DHAP on seed germination in P. schrenkiana ssp. tianschanica depended on treatment concentrations, in the order of 5.0 mmol·L^–1 > 0.1 mmol·L^–1 > 1.0 mmol·L^–1 > control; treatments with DHAP reduced the concentrations of ZT and GA₃, delayed the peak occurrence of GA₃, and increased the concentration of ABA with a delayed peak occurrence under treatments of 1.0 and 5.0 mmol·L^–1 DHAP. Treatment with 5.0 mmol·L^–1 DHAP for 3–6 days greatly increased the level of IAA. 1–6 days of treatments with DHAP reduced the ZT/(GA₃ + IAA) ratio, and increased the IAA/ZT ratio and ABA/ZT ratio; theABA/(ZT + GA₃ + IAA) ratio increased at 0.1 mmol·L^–1 DHAP and decreased at 5.0 mmol·L^–1 DHAP. It is suggested that DHAP treatment causes changes in the content and balance of endogenous plant hormones, leading to inhibition or delaying in seed germination in P. schrenkiana ssp. tianschanica.