Abstract：
The exploration of microbial resources to reduce Pb accumulation in rice attracted great attention. In this study, we found Penicillium oxalicum SL2, a Pb-tolerant strain with good capability of dissolving phosphorus and stabilizing Pb in soil, was able to colonize on the root surface of rice seedlings without additional carbon sources, and promoted the secretion of metabolites related to amino acid metabolism, organic acid metabolism, signal transduction and other pathways in rhizosphere exudates, in which the secretion of oxalate increased by 47.7 %. However, P. oxalicum SL2 increased Fe(II) proportion and Fe availability on the root surface, resulting in iron plaque content decrease. Moreover, by converting root surface Pb from Pb-Fe state to PbC2O4 and Pb-P compounds, P. oxalicum SL2 increased Pb intercept capacity of iron plaque by 118.0 %. Furthermore, P. oxalicum SL2 regulated element distribution on the root surface, and reduced the relative content of Pb on the maturation zone of root tip, which was conducive to reducing Pb uptake by apoplastic pathway and the risk of Pb accumulation in root system. Our findings further revealed the interaction between P. oxalicum SL2 and rice root, providing a theoretical basis for the development and application of microbial agents in Pb-contaminated farmland.
摘要：
探索减少水稻中铅积累的微生物资源引起了人们的极大关注。在这项研究中,我们发现了草酸青霉SL2，一种耐铅的菌株，具有良好的溶解磷和稳定土壤中铅的能力，能够在没有额外碳源的情况下在水稻幼苗的根表面定殖，并促进与氨基酸代谢相关的代谢产物的分泌，有机酸代谢，根际分泌物中的信号转导和其他途径，其中草酸盐的分泌增加了47.7%。然而,草酸草SL2增加了根表面的Fe（II）比例和Fe有效性，导致铁菌斑含量降低。此外，通过将根面Pb从Pb-Fe态转化为PbC2O4和Pb-P化合物，草酸磷SL2使铁斑块的Pb截留能力提高118.0%。此外，草酸根SL2调节元素在根表面的分布，降低了根尖成熟区Pb的相对含量，这有利于减少根际发育途径对Pb的吸收和Pb在根系中积累的风险。我们的发现进一步揭示了草酸草SL2和水稻根之间的相互作用，为微生物制剂在铅污染农田中的开发和应用提供理论依据。
