Kukreti Aditya, Siddabasappa Chethana Bangi, Krishnareddy Prasannakumar Muthakapalli, Subbanna Yashavanth Basavapatna, Channappa Manjunatha, Thammayya Shivakumara Kadanakuppe, Mahmoud Eman A, Almeer Rafa
Department of Plant Pathology, University of Agricultural Sciences, GKVK, Bengaluru, 560 065, India.
National Academy of Agricultural Research Management, Hyderabad, Telangana, 500 030, India.
Heliyon. 2024 Jun 6;10(12):e32574. doi: 10.1016/j.heliyon.2024.e32574. eCollection 2024 Jun 30.
Endophytes stimulate plant growth and inhibit phytopathogens. Most of the known endophytes are host-specific and only a few strains are effective for practical field use. Thus, this study focuses on the evaluation of endophytes ., strain HP3d, strain PGSS1, strain A6 and P42 isolated from diverse crop ecosystems for their potential to promote plant growth and induce systemic resistance against sheath blight disease in rice. The endophytes were studied for plant growth promoting traits conditions and were found to exhibit ammonia (light to strong), siderophore (yellow zone on the CAS agar plate), indole-3-acetic acid (15.20-22.19 μg mL) production and phosphorus solubilization (1.2-1.5 cm). In the glasshouse, when applied individually and in combinations through various methods like seed treatment, seedling dip, and foliar spray these endophytes significantly reduced lesion size (2.06-2.37 fold) and ShB severity (2.60-2.58 fold), enhancing growth parameters ., shoot (1.09-1.11 fold), root (1.02-1.20 fold), number of tillers (1.2-1.6 fold), shoot (80.58-82.64 %) and root (62.01-66.66 %) dry matter over untreated control. Consequently, enzyme activity ., polyphenol oxidase (2.20-3.00 Uming), peroxidase (0.31-0.35 ming), superoxide dismutase (118.50-123.00 Ug FW), and phenylalanine ammonia lyase (0.84-0.90 min⁻g⁻FW) was found to increase up to the fourth day after the pathogen challenge and subsequently decrease thereafter. Chlorophyll content post inoculation of ShB declined over time but endophyte treated plants exhibited lesser reductions over uninoculated control. Field trials corroborated the findings, demonstrating reduced ShB (1.71-1.88 fold decrease in PDI) and enhanced growth (1.1-1.2 fold increase in shoot length) over untreated controls. The combined application of seedling dip, seed treatment, and foliar spray proved to be the most optimum treatment. The findings highlight the potential of diverse crop-derived endophytes, emphasizing their non-host specificity and effectiveness as broad-spectrum bioagents in actual field conditions.
内生菌可刺激植物生长并抑制植物病原体。大多数已知的内生菌具有宿主特异性，只有少数菌株在实际田间应用中有效。因此，本研究着重评估从不同作物生态系统中分离出的内生菌，即菌株HP3d、菌株PGSS1、菌株A6和P42，它们促进植物生长以及诱导水稻对纹枯病产生系统抗性的潜力。对这些内生菌的植物生长促进特性进行了研究，发现它们具有产氨能力（轻度至重度）、产生铁载体能力（在CAS琼脂平板上出现黄色区域）、产吲哚-3-乙酸能力（15.20 - 22.19μg/mL）以及溶解磷能力（1.2 - 1.5厘米）。在温室中，通过种子处理、浸苗和叶面喷施等多种方法单独或组合施用这些内生菌后，显著减小了病斑大小（降低了2.06 - 2.37倍）和纹枯病严重程度（降低了2.60 - 2.58倍），提高了生长参数，如地上部（提高了1.09 - 1.11倍）、根部（提高了1.02 - 1.20倍）、分蘖数（提高了1.2 - 1.6倍）、地上部干物质（提高了80.58 - 82.64%）和根部干物质（提高了62.01 - 66.66%），相比于未处理的对照。因此，发现酶活性，即多酚氧化酶（2.20 - 3.00 U/mg）、过氧化物酶（0.31 - 0.35 U/mg）、超氧化物歧化酶（118.50 - 123.00 U/g FW）和苯丙氨酸解氨酶（0.84 - 0.90 min⁻¹g⁻¹FW）在病原菌侵染后的第四天增加，随后下降。接种纹枯病后叶绿素含量随时间下降，但经内生菌处理的植株相比于未接种的对照下降幅度较小。田间试验证实了这些结果，表明与未处理的对照相比，纹枯病病情减轻（病情指数降低了1.71 - 1.88倍），生长增强（地上部长度增加了1.1 - 1.2倍）。浸苗、种子处理和叶面喷施的联合应用被证明是最优化的处理方法。这些发现突出了不同作物来源内生菌的潜力，强调了它们在实际田间条件下的非宿主特异性和作为广谱生物制剂的有效性。
