School of Horticulture, Anhui Agricultural University, Hefei, 230036, Anhui, P.R. China.
College of Agriculture and Life Sciences, Cornell University, Ithaca, NY, 14853, USA.
BMC Microbiol. 2022 Jan 8;22(1):18. doi: 10.1186/s12866-021-02432-7.
Fe-deficiency chlorosis (FDC) of Asian pear plants is widespread, but little is known about the association between the microbial communities in the rhizosphere soil and leaf chlorosis. The leaf mineral concentration, leaf subcellular structure, soil physiochemical properties, and bacterial species community and distribution had been analysed to gain insights into the FDC in Asian pear plant.
The total Fe in leaves with Fe-deficiency was positively correlated with total K, Mg, S, Cu, Zn, Mo and Cl contents, but no differences of available Fe (AFe) were detected between the rhizosphere soil of chlorotic and normal plants. Degraded ribosomes and degraded thylakloid stacks in chloroplast were observed in chlorotic leaves. The annotated microbiome indicated that there were 5 kingdoms, 52 phyla, 94 classes, 206 orders, 404 families, 1,161 genera, and 3,043 species in the rhizosphere soil of chlorotic plants; it was one phylum less and one order, 11 families, 59 genera, and 313 species more than in that of normal plant. Bacterial community and distribution patterns in the rhizosphere soil of chlorotic plants were distinct from those of normal plants and the relative abundance and microbiome diversity were more stable in the rhizosphere soils of normal than in chlorotic plants. Three (Nitrospira defluvii, Gemmatirosa kalamazoonesis, and Sulfuricella denitrificans) of the top five species (N. defluvii, G. kalamazoonesis, S. denitrificans, Candidatus Nitrosoarchaeum koreensis, and Candidatus Koribacter versatilis). were the identical and aerobic in both rhizosphere soils, but their relative abundance decreased by 48, 37, and 22%, respectively, and two of them (G. aurantiaca and Ca. S. usitatus) were substituted by an ammonia-oxidizing soil archaeon, Ca. N. koreensis and a nitrite and nitrate reduction related species, Ca. K. versatilis in that of chlorotic plants, which indicated the adverse soil aeration in the rhizosphere soil of chlorotic plants. A water-impermeable tables was found to reduce the soil aeration, inhibit root growth, and cause some absorption root death from infection by Fusarium solani.
It was waterlogging or/and poor drainage of the soil may inhibit Fe uptake not the amounts of AFe in the rhizosphere soil of chlorotic plants that caused FDC in this study.
亚洲梨树缺铁性黄化症普遍存在，但人们对根际土壤微生物群落与叶片黄化的关系知之甚少。本研究通过分析叶片矿质元素含量、叶片亚细胞结构、土壤理化性质、细菌物种群落和分布，探讨亚洲梨树缺铁性黄化症的成因。
缺铁叶片的总铁含量与全钾、镁、硫、铜、锌、钼和氯含量呈正相关，但在黄化和正常植株根际土壤中，有效铁（AFe）含量无差异。黄化叶片中观察到核糖体降解和叶绿体类囊体堆叠降解。注释微生物组表明，黄化植株根际土壤中存在 5 个王国、52 个门、94 个纲、206 个目、404 个科、1161 个属和 3043 个种；与正常植株相比，少 1 个门、1 个目、11 个科、59 个属和 313 个种。黄化植株根际土壤的细菌群落和分布模式明显不同于正常植株，正常植株根际土壤的相对丰度和微生物组多样性更为稳定。在两种根际土壤中，前 5 种丰度最高的物种中有 3 种（Nitrospira defluvii、Gemmatirosa kalamazoonesis 和 Sulfuricella denitrificans）是相同的，且均为需氧菌，但它们的相对丰度分别下降了 48%、37%和 22%，其中 2 种（G. aurantiaca 和 Ca. S. usitatus）被氨氧化土壤古菌 Ca. Nitrosoarchaeum koreensis 和与亚硝酸盐和硝酸盐还原相关的物种 Ca. Koribacter versatilis 取代，这表明黄化植株根际土壤的土壤通气不良。发现不透水表降低了土壤通气性，抑制了根系生长，并导致一些吸收根因感染茄腐镰刀菌而死亡。
可能是土壤积水或（和）排水不良抑制了铁的吸收，而不是黄化植株根际土壤中 AFe 的含量导致了本研究中的缺铁性黄化症。
