Diversity of sugarcane root‐associated endophytic Bacillus and their activities in enhancing plant growth

Abstract

Aims Plant tissues are the reservoirs of beneficial and harmful microbes that regulates plant growth. In the present study, we investigated the diversity, function and colonization of sugarcane roots associated with Bacillus spp. Methods and Results A total of 20 Bacillus strains were isolated and identified by 16S rRNA gene sequencing, and their genetic diversity was examined by BOX, ERIC, REP, (GTG)5 PCR techniques. Among all Bacillus isolates, 65% showed indole acetic acid‐like compounds production, 50% solubilized phosphorus and 25% of the isolates were able to secrete siderophore. Moreover, all 20 Bacillus isolates showed antifungal activity against eight fungal pathogens and 11 of them (55%) antagonized tomato grey mold. Based on the plant growth‐promoting traits and antifungal potential, isolate Y8 was selected for root and plant tissue colonization assays and a greenhouse‐level sugarcane growth promotion study. Fluorescence microscopy results confirmed that isolate Y8 has a strong ability to colonize in the sugarcane root and leaves, and the root surface association of Y8 was confirmed by scanning electron microscopy. Furthermore, greenhouse experimental results demonstrated that Y8 has a significant effect on enhancing sugarcane biomass and root length. Conclusions Endophytic Bacillus strains have growth‐promoting properties and anti‐fungal ability that can enhance plant fitness in an eco‐friendly manner. Significance and Impact of the Study Endophytic Bacillus strains would be a potential alternative to chemical fertilizer as well as a biocontrol agent in the future.

Endophytic Bacillus Bacteria Living in Sugarcane Plant Tissues and Telchin licus licus Larvae (Drury) (Lepidoptera: Castniidae): The Symbiosis That May Open New Paths in the Biological Control

“…B. australimaris were found to be associated with sugarcane roots grown in China (Wang et al, 2019). All these studies point out the importance of the interaction of endophytic microorganisms with plants, since they promote plant growth and have interesting characteristics for biocontrol of pests and diseases.…”

“…The endophytic species B. amyloliquefaciens , B. aryabhattai , B. safensis , B. aerophilus , and B. subtilis have been isolated from sugarcane roots grown in Thailand ( Kruasuwan and Thamchaipenet, 2016 ) and the species B. subtilis , B. cereus and B. pumilus were isolated from the apoplast fluid of sugarcane grown in Cuba ( Velázquez et al, 2008 ). Recently, eleven endophytic Bacillus species such as B. luciferensis , B. aryabhattai , B. altitudinis , B. tequilensis , B. megaterium , B. acidiceler , B. pacificus , B. solisilvae , B. velezensis , B. tropicus , and B. australimaris were found to be associated with sugarcane roots grown in China ( Wang et al, 2019 ). All these studies point out the importance of the interaction of endophytic microorganisms with plants, since they promote plant growth and have interesting characteristics for biocontrol of pests and diseases.…”

“…Endophytic bacteria are known to colonize, at some stage of their life cycle, internal tissues of the host plants without causing any visual pathogenic symptoms in plant cells ( Azevedo et al, 2000 ; Hardoim et al, 2015 ). Endophytic microorganisms can promote host plant development, as has been shown in sugarcane plants inoculated with endophytic bacteria, which can produce auxin, secrete siderophore and solubilize phosphorus ( Wang et al, 2019 ). In addition, endophytic microorganisms have also shown antagonistic activity against several pathogenic bacteria and fungi ( Lanna-Filho et al, 2017 ; Shahzad et al, 2017 ; Wang et al, 2019 ).…”

“…Endophytic microorganisms can promote host plant development, as has been shown in sugarcane plants inoculated with endophytic bacteria, which can produce auxin, secrete siderophore and solubilize phosphorus ( Wang et al, 2019 ). In addition, endophytic microorganisms have also shown antagonistic activity against several pathogenic bacteria and fungi ( Lanna-Filho et al, 2017 ; Shahzad et al, 2017 ; Wang et al, 2019 ).…”

“…In this way, searching for Bacillus bacteria that endophytically colonize sugarcane grown in the region could allow the identification of strains with high biological potential to control the giant borer. There have been a few reports on the occurrence of Bacillus species associated with roots of sugarcane grown in China ( Wang et al, 2019 ) and culm apoplast fluid of the plant grown in Cuba ( Velázquez et al, 2008 ). Several Bacillus species were isolated from the apoplast fluid of sugarcane grown in Brazil ( Melo et al, 2021 ).…”