A Biocontrol Strain of Serratia plymuthica MM Promotes Growth and Controls Fusarium Wilt in Watermelon
Author:
Li Zhaoyu1ORCID, Ma Jinxiu1, Li Jiajia1, Chen Yinglong2ORCID, Xie Zhihong3, Tian Yongqiang1, Su Xu4, Tian Tian1ORCID, Shen Tong1
Affiliation:
1. School of Biological and Pharmaceutical Engineering, Lanzhou Jiaotong University, Lanzhou 730070, China 2. The UWA Institute of Agriculture, School of Agriculture and Environment, The University of Western Australia, Perth, WA 6009, Australia 3. National Engineering Research Center for Efficient Utilization of Soil and Fertilizer Resources, College of Resources and Environment, Shandong Agricultural University, Tai’an 271018, China 4. Laboratory of Biodiversity Formation Mechanism and Comprehensive Utilization of the Qinghai-Tibet Plateau in Qinghai Province, Qinghai Normal University, Xining 810008, China
Abstract
Fusarium wilt, caused by Fusarium oxysporum f. sp. niveum (FON), is a predominant and devastating soil-borne disease that results in significant yield losses in watermelon cultivation. In this study, a strain MM isolated from the herbage rhizosphere soil, exhibited an inhibition rate of 65.46% against FON, leading to mycelial collapse, atrophy, and deformation. In pot experiments, strain MM effectively controlled Fusarium wilt of watermelon, showing a control efficacy of 74.07%. Through morphological observation and 16S rDNA gene sequencing, strain MM was identified as Serratia plymuthica. Additionally, S. plymuthica MM demonstrated antagonistic activity against eight plant pathogens, indicating that MM had broad-spectrum antifungal activity. The strain also exhibited the ability to synthesize siderophores and indole acetic acid (IAA), both of which are growth-promoting compounds. Moreover, strain MM secreted various extracellular enzymes, including protease, chitinase, β-glucanase, and cellulase. This ability allowed S. plymuthica MM to readily colonize watermelon roots and promote seedling growth. Inoculation with S. plymuthica MM increased the activity of PAL, POD, PPO, and CAT enzymes associated with watermelon defense. Furthermore, qRT-PCR analysis revealed up-regulation of LOX, POD, PAL, ClPR3, and C4H genes, which are related to plant disease resistance. The results indicated that S. plymuthica MM enhances watermelon plants’ resistance to FON by activating the JA, SA, and shikimic acid phenylpropanoid–lignin synthesis pathways. Gas chromatography–mass spectrometry (GC-MS) analysis of S. plymuthica MM culture supernatant identified piperazinedione, pyrrolo[1,2-a]pyrazine-1,4-dione, and octadecenamide as the main antimicrobial substances. Overall, S. plymuthica MM shows promise as a biocontrol agent against Fusarium wilt of watermelon, suggesting its potential for the development of a new biocontrol agent.
Funder
Gansu Jiayuguan city science and technology key research and development project Key R&D program of Shandong Province Industrial Support Program of Gansu Province Education Department Qinghai Provincial Central Government Guide Local Science and Technology Development Project Key Research and Development Program of Gansu Province
Subject
Agronomy and Crop Science
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