Chinese Journal of Plant Ecology (植物生态学报) 2013/37:12 PP.1114-1122
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 objec-tives of this study were to investigate changes in the content of endogenous plant hormones during seed germina-tion 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), in-dole-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 meas-ured 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. tian-schanica 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 treat-ments with DHAP reduced the ZT/(GA3 + IAA) ratio, and increased the IAA/ZT ratio and ABA/ZT ratio; the ABA/(ZT + GA3 + IAA) ratio increased at 0.1 mmol·L–1 DHAP and decreased at 5.0 mmol·L–1 DHAP. It is sug-gested 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.