Jēkabsone Astra, Andersone-Ozola Una, Karlsons Andis, Neiceniece Lāsma, Romanovs Māris, Ievinsh Gederts
Department of Plant Physiology, Faculty of Biology, University of Latvia, 1 Jelgavas Str., LV-1004 Rīga, Latvia.
Institute of Biology, University of Latvia, 4 Ojāra Vācieša Str., LV-1004 Rīga, Latvia.
Plants (Basel). 2022 Apr 22;11(9):1141. doi: 10.3390/plants11091141.
Biological nitrogen fixation by legume-rhizobacterial symbiosis in temperate grasslands is an important source of soil nitrogen. The aim of the present study was to characterize the dependence of different accessions of a rare crop wild relative legume species, from their native rhizobia as well as additional nitrogen fertilization in controlled conditions. Asymbiotically cultivated, mineral-fertilized plants gradually showed signs of nitrogen deficiency, appearing as a decrease in leaf chlorophyll concentration, leaf senescence, and a decrease in growth rate. The addition of nitrogen, and the inoculation with native rhizobia, or both treatments significantly prevented the onset of these symptoms, leading to both increase in plant shoot biomass as well as an increase in tissue concentration of N. The actual degree of each type of response was genotype-specific. Accessions showed a relatively similar degree of dependence on nitrogen (70-95% increase in shoot dry mass) but the increase in shoot dry mass by inoculation with native rhizobia ranged from 27 to 85%. In general, there was no correlation between growth stimulation and an increase in tissue N concentration by the treatments. The addition of N or rhizobial inoculant affected mineral nutrition at the level of both macronutrient and micronutrient concentration in different plant parts. In conclusion, native rhizobial strains associated with geographically isolated accessions of at the northern range of distribution of the species represent a valuable resource for further studies aimed at the identification of salinity-tolerant N-fixing bacteria for the needs of sustainable agriculture, as well as in a view of understanding ecosystem functioning at the level of plant-microorganism interactions.
温带草原豆科植物与根际细菌共生进行的生物固氮是土壤氮的重要来源。本研究的目的是在可控条件下，表征一种珍稀作物野生近缘豆科植物不同种质对其原生根瘤菌以及额外氮肥的依赖性。非共生培养且施用矿物肥料的植物逐渐出现氮缺乏症状，表现为叶片叶绿素浓度降低、叶片衰老以及生长速率下降。添加氮肥、接种原生根瘤菌或两种处理均显著预防了这些症状的出现，导致植株地上部生物量增加以及组织氮浓度升高。每种反应的实际程度具有基因型特异性。种质对氮的依赖程度相对相似（地上部干重增加70 - 95%），但接种原生根瘤菌使地上部干重增加的幅度在27%至85%之间。总体而言，处理对生长的刺激与组织氮浓度的增加之间没有相关性。添加氮或根瘤菌接种剂会影响不同植物部位大量元素和微量元素浓度水平的矿质营养。总之，与该物种分布北界地理隔离的种质相关的原生根瘤菌菌株，是进一步研究的宝贵资源，这些研究旨在为可持续农业需求鉴定耐盐固氮细菌，以及从植物 - 微生物相互作用层面理解生态系统功能。
