Chin J Plant Ecol ›› 2009, Vol. 33 ›› Issue (1): 186-196.DOI: 10.3773/j.issn.1005-264x.2009.01.021

• Research Articles • Previous Articles     Next Articles

BIOLOGICAL ACTIVITY AND QUANTIFICATION OF POTENTIAL AUTOTOXINS FROM THE LEAVES OF PICEA SCHRENKIANA

PAN Cun-De1, WANG Qiang2,*(), RUAN Xiao2, LI Zhao-Hui1,2   

  1. 1Department of Forestry, Xinjiang Agriculture University, Urumqi 830052, China
    2Ningbo Institute of Technology, Zhejiang University, Ningbo, Zhejiang 315100, China
  • Received:2007-12-13 Accepted:2008-02-01 Online:2007-12-13 Published:2009-01-30
  • Contact: WANG Qiang

Abstract:

Aims Schrenk spruce (Picea schrenkiana) forest is an important zonal vegetation in Tianshan Mountain, northwestern China. In addition to being an important timber resource, P. schrenkiana has important soil and water conservation functions and makes up 98.6% of the total stand volume in the region. Schrenk spruce forest exhibits slow growth, regeneration obstacles, declining productivity and confusing size and age structure. Our aims were to 1) compare autotoxicities of three organic fractions from leaves and 2) identify autotoxins from leaves. Findings could improve understanding the mechanisms of P. schrenkiana autotoxicity.
Methods Fresh leaves were extracted with water and partitioned against diethyl ether, ethyl acetate and n-butanol sequentially. We tested the three organic fractions for inhibitory activity, using germination rate, vigor and index as germination parameters and radicle and plumule elongation and weight (wet and dry) change of seedlings as seedling growth parameters. We investigated the chemical nature of the three fractions using GC-MS-MS and NMR. The chemicals in the samples were estimated on the basis of ion-molecular messenger of MS-MS spectral of samples and MS-MS user library spectra of pure reference compounds. These findings were confirmed by comparing the retention time and mass spectral in the GC-MS-MS of samples with those of reference standards under the same conditions.
Important findings The diethyl ether fraction exhibited the strongest phytotoxicity, reducing seed germination at low concentration (IC50 = 5.84 mg·ml-1), and n-butanol had the weakest effect (IC50 > 10.00 mg·ml-1). The diethyl ether fraction had a significant inhibitory effect on seedling growth at a concentration of 1.25 mg·ml-1, whereas, the n-butanol fraction at 1.25 mg·ml-1 stimulated it and at 2.5 mg·ml-1 inhibited it. Seventeen secondary metabolites were identified and quantified in the three fractions, including 2-keto-4a-methyl-8-methoxy-2,3,4,4a,5,6,11,12-ocahydro chrysene in the diethyl ether fraction (this metabolite had been found but not previously reported as an allelochemical). When we used identified components to prepare synthetic mixtures, it showed the same inhibitory effect on seed germination and seedling growth as did the three fractions.

Key words: autotoxicity, Picea schrenkiana, extracts, germination index