Identification and Assessment of a Biocontrol Agent, Ochrobactrum intermedium I-5, for Management of Alfalfa Root Rot Caused by Fusarium tricinctum

Abstract

Alfalfa root rot caused by Fusarium tricinctum is one of the most important soil-borne diseases resulting in significant losses to alfalfa agriculture worldwide. Fungicides used in management of disease affect the environment and human health. In this study, a strain of Ochrobactrum intermedium (I-5), isolated from alfalfa rhizosphere soil, exhibited strong antifungal activity against a number of causative pathogens of alfalfa root rot, and showed the strongest antagonistic activity against F. tricinctum (the longest radius/shortest radius ratio of 3.09). When applied at 10%, a filtrate of I-5 liquid culture significantly reduced the spore production and germination and mycelial growth of F. tricinctum, and the inhibition rate was 76.67%, 78.93% and 55.77%, respectively. Furthermore, a filtrate and suspension of the strain, when applied at 10%, reduced alfalfa root rot by more than 73%. The strain clearly promoted the activities of invertase, urease, cellulose, and neutral phosphatase in alfalfa rhizosphere soil and significantly reduced the damage to rhizosphere soil quality attributable to alfalfa root rot. Moreover, the strain clearly promoted the growth of alfalfa, without causing any evident damage to plants. The active substance produced by the strain was relatively insensitive to heat and ultraviolet irradiation and displayed optimal efficacy at pH 8. To the best of our knowledge, this is the first study describing the use of O. intermedium for the biological control of alfalfa root rot. O. intermedium (I-5) has considerable potential for application in the control of alfalfa root rot and improvement of the quality of cultivated alfalfa.

Biological Control Ability and Antifungal Activities of Bacillus velezensis Bv S3 against Fusarium oxysporum That Causes Rice Seedling Blight

“…An aseptic filtrate of Bv S3 at a concentration of 5% was incubated in a water bath at 20, 40, 60, 80, and 100 • C and autoclaved (121 • C) for 20 min. Then, the impact of aseptic filtrates treated with different temperatures on the mycelial growth of F. oxysporum was evaluated [46]. Following a 7 d incubation period at room temperature, the mycelial diameters of the different treatment groups were measured, and the mycelial growth rate method was used to calculate the inhibition rate.…”

Root rot a silent alfalfa killer in China: Distribution, fungal, and oomycete pathogens, impact of climatic factors and its management

“…On the surface of roots, necrotic spots are formed, the tangential face of roots becomes brown or black, and reddish-brown or dark brown stripes/lesions are formed. The roots’ internal and external portions show red-brown discolorations ( Berg et al, 2017 ; Wang et al, 2020a ; Li et al, 2021a ). In the later stage of the disease, the plants become weak and can be easily removed from the earth.…”

“…cause severe damage to those alfalfa plants which are already weakened or injured by other abiotic factors, i.e., stress factors. For example low soil temperature and soil compaction predispose alfalfa to Fusarium root rot ( Li et al, 2021a ). Further , Fusarium spp.…”

“…Besides, the strain enhanced invertase, urease, cellulose, and neutral phosphatase activity in the rhizosphere soil and reduced root rot-related soil quality damage. Also promoted the growth of alfalfa without causing apparent damage to plants ( Li et al, 2021a , c ). Currently, antagonists which are endophytes have also been used to manage root rot.…”

Maize plant expresses SWEET transporters differently when interacting with Trichoderma asperellum and Fusarium verticillioides, two fungi with different lifestyles

“…Trichoderma synthesizes a broad spectrum of molecules to fulfill their role as biocontrol, including those that directly attack pathogens, such as bactericides, volatile antibiotics, cell wall degrading enzymes, and proteases ( Benítez et al., 2004 ; Vinale et al., 2008 ; Druzhinina et al., 2011 ; Sharma and Sharma, 2020 ). Contrary to Trichoderma , most Fusarium species are considered pathogens with detrimental effects on plant development and produce several plant diseases, including Fusarium head blight in wheat ( Palacios et al., 2021 ), oat ( Ghimire et al., 2020 ), and barley ( Martínez et al., 2021 ); root rot in soybean ( Hafez et al., 2021 ) and alfalfa ( Li et al., 2021 ); and stem rot and ear rot in maize ( Oldenburg et al., 2017 ). Thus, crop losses caused by Fusarium species are an important limitation to food security.…”