o:602 Diversity and plant growth promoting potential of rhizobia isolated from root nodules of Lotus corniculatus l. en Abstract: Lotus corniculatus L. is a perennial legume plant that enters into a symbiotic relationship with nitrogen-fixing bacteria belonging to Mesorhizobium genus by forming root nodules within which the nitrogen fixation occurs. This plant is a valuable forage crop of high nutritional value that thrives on less fertile and/or degraded soils. The analysis of bacterial diversity within the root nodules of Lotus corniculatus is indispensable, as nitrogen fixing bacteria could be used to promote the growth of this valuable plant. The aim of this research was to isolate and determine endophytic rhizobial bacteria from root nodules of Lotus corniculatus L. and to evaluate their plant growth promoting (PGP) characteristics. Nitrogen fixation efficiency as well as the ability of isolates to produce PGP substances such as indole-3-acetic acid (IAA), siderophores and to solubilise inorganic phosphates was evaluated in vitro. In addition, antifungal activity of isolates against three fungi belonging to Fusarium genus (F. oxysporum, F. graminearum and F. proliferatum), as well the ability to produce hydrolytic enzymes, such as amylase, cellulase, protease and pectinase was tested in vitro. In total, 72 bacterial isolates from the root nodules of Lotus corniculatus L. sampled on the territory of Republic of Serbia were isolated. Nodulation test showed that 58 isolates could infect the plant and form nodules on Lotus corniculatus L. roots. Overall, 50 isolates produced IAA in a wide range of concentrations, 29 isolates could solubilise inorganic phosphates, while siderophores production was not recorded. Only few isolates had the ability to produce hydrolytic enzymes, while antifungal activity against tested fungi was not recorded. The most effective isolates were subjected to further molecular characterisation based on 16S rDNA sequence. Sequencing results showed that isolates DZM1Cm, DZK1Lm, PZR1Dm, DRZR2Cm, 631oz, 754 and 1M12 belong to Mesorhizobium genus (Mesorhizobium sp., Mesorhizobium cantuariense, Mesorhizobium erdmanii, Mesorhizobium sp., Mesorhizobium sp., Mesorhizobium jervisi and Mesorhizobium sp., respectively). The results of this research indicated that there is wide rhizobial diversity present in the root nodules of Lotus corniculatus L. Further research should be aimed towards exploring the potential application of identified effective root nodule rhizobia in contemporary agriculture and organic farming. Sažetak Identifikator monografske publikacije: ISBN 978-86-912877-4-0 Lotus corniculatus L., Mesorhizobium sp., nitrogen fixation, plant growth promotion, indole-3-acetic acid 2022-09-08T10:50:58.536Z 44 yes 46 Magdalena Knežević Institute of Soil Science 0000-0003-0186-3652 46 Aneta Buntić Institute of Soil Science 0000-0002-7068-1804 46 Merisa Avdović Centro de Biotecnología y Genómica de Plantas UPM, Pozuelo de Alarcon 46 Nataša Rasulić Institute of Soil Science 0000-0003-2807-0775 46 Đorđe Kuzmanović Institute of Soil Science 46 Dušica Delić Institute of Soil Science 0000-0002-0626-0482 46 Olivera Stajković-Srbinović 0000-0001-9759-843X application/pdf 1072800 https://unilib.phaidrabg.rs/o:602 no yes 1 70 92000004 71A05 3rd International and 15th National Congress SOILS FOR FUTURE UNDER GLOBAL CHALLENGES 23 23 Serbian Society of Soil Science 2021