Journal of Hazardous Materials：木质素侧链区参与油菜中Cd积累的解毒过...

中山大学生命科学学院杨中艺教授课题组测定了在对照及Cd处理环境中生长的低累积Cd和高累积Cd品种油菜中的Cd及木质素含量、木质素组成与漆酶（LAC）基因表达，以探讨木质素在品种依赖性Cd解毒中的作用。相关成果发表于Journal of Hazardous Materials（IF=7.650）。

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Highlights

·Lignin is an important Cd repository in SCW of Brassica chinensis L.

·LAC genes are involved in the cultivar-dependent lignin functions.

·Lignin side chain region participates in cultivar-dependent complexation with Cd.

·Cd fixation in SCW involved in different Cd accumulation through detoxification.

Abstract

To investigate the effect of lignin in the cultivar-dependent Cd detoxification of Brassica chinensis L., Cd and lignin contents, lignin composition and laccase genes expressions in low-Cd-accumulating (LAJK) and high-Cd-accumulating (HAJS) cultivars grown under control (CK) and 25 μM Cd-treatment were determined. The results showed that lignin combined about 14 % of total Cd in both LAJK and HAJS. LAC genes were more up-regulated in HAJS than in LAJK, indicating that the LAC genes were involved in the cultivar-dependent lignin functions. Higher β-aryl ether (A) proportion in the lignin side chain region in LAJK than in HAJS were observed, whereas resinol (B) and phenylcoumaran (C) constitute much higher proportions in HAJS than in LAJK. Chemical calculation to estimate Cd affinity associating with lignin side chain region displayed that i) β-aryl ether (A) exhibited major coupling with lignin aromatic region; ii) resinol (B) and phenylcoumaran (C) displayed major participation in complexation with Cd. We therefore conclude that Cd compartmentalization in the secondary cell wall (SCW) by coupling with lignin side chain region is responsible for Cd detoxification related to cultivar-dependent Cd accumulation of Brassica chinensis. This is the first study on lignin composition in relation to Cd retention mechanisms in SCW.

为了探讨木质素在品种依赖性镉（Cd）解毒中的作用，测定了在对照（CK）及25μM Cd处理环境中生长的Cd低累积（LAJK）和Cd高累积（HAJS）品种油菜中的Cd及木质素含量、木质素组成与漆酶（LAC）基因表达。结果表明，木质素结合的Cd在LAJK和HAJS中均占总Cd的14%左右。HAJS中LAC基因的表达高于LAJK，说明LAC基因参与了品种依赖性木质素功能。在LAJK中，木质素侧链区域中的β-芳基醚（A）比例高于HAJS，而在HAJS中，树脂醇（B）和苯基香豆素（C）的比例要高于LAJK。使用化学计算估算与木质素侧链区域结合的Cd亲和力结果表明：i）β-芳基醚（A）主要与木质素芳香族区域具有偶联作用；ii）树脂醇（B）和苯基香豆素（C）主要与Cd具有络合作用。研究据此得出的结论是：通过与木质素侧链区域偶联而使次级细胞壁（SCW）中的Cd区室化是造成品种依赖性油菜Cd积累解毒的原因。这是关于SCW中木质素组成与Cd积累机制相关性的首次研究。