Aposymbiosis of a <i>Burkholderiaceae</i>-Related Endobacterium Impacts on Sexual Reproduction of Its Fungal Host

Abstract

Bacterial endosymbionts inhabit diverse fungal lineages. Although the number of studies on bacteria is increasing, the mechanisms by which bacteria affect their fungal hosts remain unclear. We herein examined the homothallic isolate, Mortierella sugadairana YTM39, harboring a Burkholderiaceae-related endobacterium, which did not produce sexual spores. We successfully eliminated the bacterium from fungal isolates using ciprofloxacin treatment and asexual spore isolation for germinated asexual spores. Sexual spore formation by the fungus was restored by eliminating the bacterium from isolates. These results indicate that sexual reproduction by the fungus was inhibited by the bacterium. This is the first study on the sexual spore infertility of fungal hosts by endofungal bacteria.

First Report of Tripartite Symbiosis Potential among Soybean, Bradyrhizobium japonicum, and Dark Septate Endophytes

“…These two candidates were chosen because of their successful plant-growth-promoting effects, according to previous research [33,34]. The isolates were recovered from glycerol culture stock on 1 2 CMMY medium with a pH value of 5.6 (8.5 g of corn meal agar, 7.5 g of bacto agar, 10 g of malt extract, 1 g of yeast extract, and 1000 mL of distilled water) [35]. Each fungus was grown in 55 mm sterile Petri dishes at room temperature (approximately 23 • C) for four weeks.…”

Whole-Genome Sequence of Entomortierella parvispora E1425, a Mucoromycotan Fungus Associated with Burkholderiaceae -Related Endosymbiotic Bacteria

“…Soilborne fungi of Mortierella spp. harbor Burkholderiaceae -related endobacteria (BRE) ( 1 – 7 ) that can protect the host from nematode attack and inhibit zygospore formation ( 8 , 9 ). Entomortierella parvispora E1425 (JCM 39028, synonymously known as Mortierella parvispora E1425) isolated from forest soil possesses a cultivable BRE named Mycoavidus sp.…”

“…To eliminate the endobacteria, germinated sporangiospores of E1425 were treated with ciprofloxacin (50 μg mL −1 ) at 23°C for 24 h and then incubated on fresh LC A medium ( 6 ) until fungal colonies appeared ( 9 ). After confirming the absence of BRE by diagnostic PCR in accordance with Takashima et al ( 9 ), an endobacterium-cured line of E1425 was established and incubated on half-strength cornmeal-malt-yeast (CMMY) medium ( 2 ) at 23°C for 7 days ( 9 ). DNA and RNA were extracted from homogenized mycelia of endobacterium-cured E1425 using phenol-chloroform extraction ( 11 ) with a Genomic tip 100/G (Qiagen) and an RNeasy minikit (Qiagen), respectively.…”

Endofungal bacteria boost anthelminthic host protection with the biosurfactant symbiosin

“…[23][24][25][26] In these partnerships the bacteria live inside the fungal hyphae and benet from a steady environment and nutritional support. Meanwhile, the fungus can be inuenced in its reproduction, [27][28][29] growth behavior, 30 energy dynamics, 31 and by host-supporting secondary metabolites biosynthesized by the bacterium. 32,33 Symbioses between fungi and endobacteria are most abundant in the fungal phylum Mucoromycota, harboring Burkholderia-related bacteria.…”

“…23–26 In these partnerships the bacteria live inside the fungal hyphae and benefit from a steady environment and nutritional support. Meanwhile, the fungus can be influenced in its reproduction, 27–29 growth behavior, 30 energy dynamics, 31 and by host-supporting secondary metabolites biosynthesized by the bacterium. 32,33…”