Bent Elizabeth, Loffredo Angelo, Yang Jiue-In, McKenry Michael V, Becker Jörn Ole, Borneman James
Department of Plant Pathology and Microbiology, University of California, Riverside, CA 92521, USA.
FEMS Microbiol Ecol. 2009 May;68(2):192-200. doi: 10.1111/j.1574-6941.2009.00668.x.
Replant diseases often occur when pome and stone fruits are grown in soil that had previously been planted with the same or similar plant species. They typically lead to reductions in plant growth, crop yield and production duration. In this project, greenhouse assays were used to identify a peach orchard soil that caused replant disease symptoms. Biocidal treatments of this soil led to growth increases of Nemaguard peach seedlings. In addition, plants grown in as little as 1% of the replant soil exhibited reduced plant growth. These results suggest that the disease etiology has a biological component. Analysis of roots from plants exhibiting various levels of replant disease symptoms showed little difference in the amounts of PCR-amplified bacterial or fungal rRNA genes. However, analysis using a stramenopile-selective PCR assay showed that rRNA genes from this taxon were generally more abundant in plants with the smallest top weights. Nucleotide sequence analysis of these genes identified several phylotypes belonging to Bacillariophyta, Chrysophyceae, Eustigmatophyceae, Labyrinthulida, Oomycetes, Phaeophyceae and Synurophyceae. Sequence-selective quantitative PCR assays targeting four of the most abundant phylotypes showed that both diatoms (Sellaphora spp.) and an oomycete (Pythium ultimum) were negatively associated with plant top weights.
当仁果类和核果类水果种植在先前种植过相同或相似植物物种的土壤中时，常常会发生再植病害。它们通常会导致植物生长、作物产量和生产持续时间下降。在本项目中，利用温室试验来鉴定一种能引发再植病害症状的桃园土壤。对这种土壤进行杀菌处理后，Nemaguard桃树苗的生长有所增加。此外，在仅1%的再植土壤中生长的植物，其生长也受到了抑制。这些结果表明，该病害的病因具有生物学成分。对表现出不同程度再植病害症状的植物根系进行分析，结果显示，经PCR扩增的细菌或真菌rRNA基因数量几乎没有差异。然而，使用针对不等鞭毛类的选择性PCR检测分析表明，在地上部重量最小的植物中，来自该分类群的rRNA基因通常更为丰富。对这些基因进行核苷酸序列分析，鉴定出了几种属于硅藻纲、金藻纲、黄藻纲、网黏菌纲、卵菌纲、褐藻纲和 Synurophyceae 的系统发育型。针对四种最丰富的系统发育型进行的序列选择性定量PCR检测表明，硅藻（Sellaphora spp.）和一种卵菌（终极腐霉）均与植物地上部重量呈负相关。
