Abstract: 【Objective】The objectives of this study were to examine the subcellular distribution of lead (Pb) and various chemical extraction in wheat cultivars Bainong160 and Yanzhan4110, to provide theoretical support for screening for cultivars of wheat with low Pb accumulation. 【Method】Based on a preliminary investigation, two wheat cultivars with different characteristics of Pb absorption were selected as study materials. A sand-culture experiment was carried out at three levels of Pb stress: 0 (control), 100 and 800 mg·L^-1 Pb as Pb (NO₃)₂. After 4-week Pb stress, the plant was harvested. Biomass, subcellular distribution and chemical extraction of Pb were determined, and the differences in biomass, subcellular distribution and chemical extraction of Pb between two wheat cultivars under Pb stress were analyzed. 【Result】 Pb at 100 mg·L^-1 could improve the growth of wheat. Bainong160 and Yanzhan4110 had a 4.78% and 2.66% increase in biomass, respectively. When the concentration of Pb increased to 800 mg·L^-1, wheat growth was inhibited. There were 25.66% and 38.60% decrease in biomass for Bainong160 and Yanzhan4110, respectively. In addition, there was a difference in root/shoot ratio between the two cultivars. When the concentration of Pb increased from 100 mg·L^-1 to 800 mg·L^-1, Bainong160 had no increase, but there was an increase from 0.71 to 0.81 in Yanzhan4110. After 4-week stress, the Pb contents of stems and leaves, and roots in Bainong160 were lower than those in Yanzhan4110. For subcellular distribution, Pb was mainly observed in the cell wall and cytoplasm, which accounted for 72%-86% of the total, in both wheat cultivars under different levels of Pb stress. When the concentration of Pb increased from 100 mg·L^-1 to 800 mg·L^-1, Yanzhan4110 had a 8% decrease in the proportion of the root cell wall and cytoplasm of Pb, and 4% decrease in this proportion stems and leaves, but the value for Bainong160 increased by 9% for root and 1% for stems and leaves. For chemical forms, poorly-soluble Pb lead (i.e. acetic acid and hydrochloric acid extractable) was mainly detected, which accounted for 67%-85% of the total. NaCl extractable Pb accounted for 6%-18% of the total, and the sum of ethanol extractable, deionized water extractable and residue Pb accounted for 8%-16%. In addition, the contents of active-Pb (i.e. ethanol and deionized water extractable) in roots of Bainong160 were lower than those in Yanzhan4110. The active-Pb in stems and leaves was different from that in roots. At the level of 100 mg·L^-1 Pb, the contents of active-Pb in stems and leaves of Bainong160 were lower than those in Yanzhan4110, when Pb increased to 800 mg L^-1, there was no difference in contents of active-Pb in stems and leaves between two cultivars.【Conclusion】Under Pb stress, root-surface of Bainong160 presented stronger resistance to Pb than Yanzhan4110. The cultivar had Pb fixation on the cell wall, which limits further transport of Pb and reduce the toxicity of Pb to shoots. For chemical forms, the distribution ratio of various forms of Pb is closely related to detoxification mechanism, but performances are not the same for different organs.

Key words: wheat, lead, biomass, subcellular distribution, chemical extraction