地黄连作胁迫响应机制的块根蛋白质组学分析

地黄种植过程中存在严重的连作障碍问题,连作导致块根无法正常膨大、产量品质下降、土传病害严重等。本研究以正、重茬地黄块根为试验材料,通过差异蛋白质组学技术分析连作下地黄块根蛋白质表达谱变化,并进一步采用qRT-PCR技术对锁定的差异蛋白质表达量变化进行验证分析。研究结果发现,连作导致与块根重要生理代谢过程和主要成分合成相关的蛋白质都下调表达,与蛋白质折叠相关的伴侣素(chaperonin)在重茬地黄块根中全部下调表达;连作下与胁迫响应、抵御相关的蛋白质(如pathogenesis-related protein 10, cytochrome P450, Type IIIa membrane protein cp-wap13等)均上调表达。qRT-PCR定量分析证实重茬地黄块根中PR-10基因表达量显著高于正茬地黄;PR-10基因在尖孢镰刀菌病原菌侵染下能够明显被诱导表达,表达量随着侵染时间的增加而逐渐升高,验证了差异蛋白质组学分析的结果。可见连作胁迫对地黄块根蛋白质表达谱有显著影响,导致蛋白质表达紊乱,连作植株生理代谢过程异常,碳水化合物和能量代谢缓慢,产生连作障碍效应。     

Stabilization of hydrophobic organic contaminants in sediments by natural zeolites: bioavailability-based assessment of efficacy using equilibrium passive sampling

Purpose

As natural zeolites have been widely used as cost-effective adsorbents for plant nutrients and heavy metals in sediments, it is worthwhile to verify the potential of natural zeolites for mixed-contaminant stabilization including hydrophobic organic contaminants (HOCs). The effectiveness of natural zeolite amendment in sediment on reducing the bioaccumulation of sediment-associated HOCs in V. philippinaram (C_b) was assessed. Then, the role of sediment pore water freely dissolved HOCs (C_free) in C_b prediction was further identified and modeled.

Materials and methods

In this study, a bioavailability-based assessment of the HOC-stabilization efficacy of natural zeolites in maricultural sediments was performed using equilibrium passive sampling. V. philippinaram was adopted as a biological indicator for HOC bioaccumulation. Polydimethylsiloxane (PDMS) was used as a passive sampler for monitoring the concentration of the C_free. The assumption that C_free is a central mediator driving the bioaccumulation process of HOCs from the bulk sediment to the exposed organisms was validated by correlating the reductions in C_b and C_free of the sediments amended with natural zeolites. Subsequently, a model based on this assumption was built and verified for the bioavailability-based assessment of the stabilization efficacy of natural zeolite amendment on sediment-associated HOCs.

Results and discussion

The results showed the bioaccumulations of four kinds of HOCs (including polycyclic aromatic hydrocarbons, polybrominated diphenyl ethers, pyrethroids, and organochlorine pesticides) in V. philippinaram were reduced by 7.3–38% after the natural zeolite amendment (10% dry weight in sediments), and the C_free values measured with PDMS were reduced proportionally. It supported the assumption that C_free is a central mediator driving the bioaccumulation process of HOCs. K_ow of HOCs and two properties of sediment were found to be significantly correlated with the reductions of the C_free values. Based on these findings, a model to predict the C_b values of PAHs and PBDEs in V. philippinaram was built. The model was then verified by a significant correlation between the predicted and measured values of C_b.

Conclusions

The potential of natural zeolites for the stabilization of mixed-contaminants in sediments, including HOCs, was proved as notable reductions of C_b and C_free of HOCs in the sediments amended by natural zeolite were observed. The results also suggested PDMS is a promising tool for predicting the bioaccumulation of sediment-associated HOCs in V. philippinaram and further for assessing the stabilization efficacy of natural zeolites in maricultural sediments. Modifying natural zeolites to further improve the effectiveness of HOC stabilization is warranted.

     

不同连作年限野生地黄根际土壤微生物群落多样性分析

以野生地黄为试验材料,设置野生地黄头茬土壤、重茬土壤和原茬土壤处理,未种植任何作物为对照,于块根膨大中期采集土样,通过磷脂脂肪酸法(PLFA)和末端限制性片段长度多态性(T-RFLP)技术,分析不同连作年限野生地黄的根际微生物生物量和群落结构变化。PLFA分析结果表明,不同处理情况下地黄根际土壤微生物群落结构存在明显差异,与头茬地黄根际土壤相比,重茬地黄土壤微生物总量显著下降,并且细菌/真菌比例下降。T-RFLP分析结果表明,不同连作年限地黄根际土壤细菌群落结构存在一定差异,野生状态地黄土壤和头茬土壤菌群较为相似,变形菌门和厚壁菌门占据优势地位。野生状态地黄和头茬地黄根际富含Bacillus、Pseudomonas等有益生防菌,而重茬地黄根际土壤滋生大量病原菌如Clostridium sp.、Flexibacter polymorphus和Clostridium ghoni,有益菌群和纤维素降解菌群减少,q RT-PCR定量分析也显示,野生状态地黄和头茬地黄土壤中假单胞菌数量都显著高于重茬地黄土壤。总之,野生地黄存在连作障碍问题,导致野生地黄根际有益菌数量减少而病原菌大量滋生,从而降低了野生地黄抵御病害的能力,使重茬野生地黄生长发育差,产量大幅降低。