Biodiversity of Culturable Endophytic Actinobacteria Isolated from High Yield Camellia oleifera and Their Plant Growth Promotion Potential

Abstract

Camellia oleifera Abel. is one of the world’s four famous woody oil trees and has drawn increasing attention because of its high commercial value. Endophytes are microorganisms inhabiting inside plant tissues, and their functions vary with the change of host status and environmental parameters. To deepen our understanding of the interactions between C. oleifera and their endophytic actinobacteria, the present study investigated the four endophytic actinobacterial composition-residing high-yield C. oleifera trees. A total of 156 endophytic actinobacterial isolates were obtained distributed in 17 genera. Among them, Streptomyces was the dominant endophytic actinobacteria, followed by Nocardia, Amycolatopsis, Microbiospora, Micromonospora and other rare actinobacteria genera. Soil characteristics including soil pH and organic matter were found to play crucial roles in shaping the endophytic actinobacterial community composition. Furthermore, all isolates were studied to determine their plant growth-promotion traits, 86.54% could produce Indole 3-Acetic Acid, 16.03% showed nitrogen-fixing, 21.15% showed phosphorus solubilizing, and 35.26% produced siderophore. Under the glasshouse condition, some isolates exhibited growth promotion effects on C. oleifera seedlings with significant increase in spring shoot length and ground diameter. Altogether, this study demonstrated that C. oleifera plants harbored a high diversity and novelty of culturable endophytic actinobacteria, which represent important potential as natural biofertilizers for the high production of C. oleifera.

Characterization of actinobacteria from wheat seeds for plant growth promoting traits and protection against fungal pathogens

“…Different ways used by microorganism to inhibit the growth of pathogens include the production of ammonia, HCN, siderophore, antifungal enzymes, and so on [47]. Among all isolates, eight, four, and one isolates produced ammonia, siderophore, and HCN, respectively, which is in agreement with the work of Chukwuneme et al [27] and Xu et al [38]. Previous studies showed that the production of extracellular hydrolytic enzymes (cellulase, amylase, pectinase, and protease) by endophytic microorganisms played indirect role in plant growth, by utilizing endospermic starch during germination and also form association with host plant by invading plant cell wall to colonize host root system [48].…”

Characterization and selection of endophytic actinobacteria for growth and disease management of Tea (Camellia sinensis L.)

“…The treatments showed enhanced biomass, height, and leaf number compared to the control. These findings are similar to earlier reports that demonstrated that actinobacteria confer benefits to host plants by boosting health and overall growth ( Passari et al., 2015 ; Passari et al., 2016a ; Vurukonda et al., 2018 ; Xu et al., 2021 ). The efficiency of the selected endophytes as PGP agents was further validated by two-way ANOVA and fold change analysis.…”

Actinobacteria–Plant Interactions in Alleviating Abiotic Stress

“…In the past few years, various endophytic actinobacterial members were reported for PGP activity. For example, endophytic Streptomyces and Amycolatopsis isolated from Camellia oleifera increased the growth of C. oleifera seedlings [ 72 ]. Similarly, Streptomyces spp.…”

“…and Amycolatopsis spp. were used in the hydroponic germination of wheat seeds, and promoted plant growth in terms of root and stem parts [ 72 ]. The genus Streptomyces was mostly dominant among the isolates recovered from leaf, stem, and root samples of tea, including Actinomadura , Kribbella , Nocardia , Kytococcus , Leifsonia , Microbacterium , Micromonospora , Mobilicoccus , Mycobacterium , Nocardiopsis , Piscicoccus , and Pseudonocardia , whereas Mobilicoccus and Piscicoccus were reported for the first time as plant endophytes [ 73 ].…”