Symbiotic Mycorrhizal Fungi Isolated via Ex Situ Seed Baiting Induce Seed Germination of Dendrobium Catenatum Lindl. (Orchidaceae)

Abstract

Shao et al.: Symbiotic mycorrhizal fungi isolated via ex situ seed baiting induce seed germination of Dendrobium catenatum Lindl.

Orchid Reintroduction Based on Seed Germination-Promoting Mycorrhizal Fungi Derived From Protocorms or Seedlings

“…As mentioned before, sgOMF isolated from protocorms or seedlings typically promote seed germination not only in vitro but also in the wild, thus showing both potential and ecological specificity (Shao et al, 2017(Shao et al, , 2018. The isolates are first verified for potential specificity in laboratories (Zi et al, 2014;Shao et al, 2017Shao et al, , 2019Meng et al, 2019c) (Figure 2). Yet, sgOMF exhibiting potential specificity does not necessarily carry ecological specificity; as that if they could stimulate in situ seed germination remains unclear.…”

“…The orchid may have fine-tuned its physiology to adapt to this fungus, thereby making the plants incapable of host-jumping for distantly related fungi (Bidartondo and Bruns, 2002), especially under in situ conditions (Masuhara and Katsuya, 1994;Perkins et al, 1995). Some sOMF and rOMF can promote orchid seed germination under controlled laboratory conditions, i.e., in vitro, thereby exhibiting potential specificity (Smith and Read, 2008;Rasmussen et al, 2015;Jacquemyn et al, 2017;Shao et al, 2019;Sathiyadash et al, 2020). If those isolates exhibiting potential specificity can successfully stimulate orchid seed symbiotic germination and survival under in situ conditions, they are considered to have ecological specificity.…”

“…Due to the lack of endosperm (Yeung, 2017 ; Zhang et al, 2017 ; Yeh et al, 2019 ), the germination of nearly all orchid seeds relies on the specific fungal partner in the wild (Bruns and Read, 2000 ; Bidartondo and Read, 2008 ; Merckx et al, 2009 ; Swarts and Dixon, 2009 ; Dearnaley et al, 2012 ; McCormick et al, 2018 ; Shao et al, 2019 ). To this end, the seed germination-promoting fungi, predominantly residing in the protocorm of the germinating seeds are known to play a key role in realizing in situ orchid seed germination and seedling formation (Selosse et al, 2017 ).…”

“…Theoretically, sgOMF could be potentially identified from sOMF or rOMF ( Figure 1 ). There may be more than one OMF species colonized at a given germinating stage (Bidartondo and Read, 2008 ; Stöckel et al, 2014 ; Shao et al, 2017 , 2019 ; Meng et al, 2019a ). These sgOMF are saprotrophic and/or endophytic in non-orchid plants (Selosse and Martos, 2014 ; Weiβ et al ., 2016 ), or concurrently ectomycorrhizal (typical for terrestrial or mycoheterotrophic orchids).…”

In Situ Seedling Baiting to Isolate Plant Growth-Promoting Fungi From Dendrobium Officinale, An Over-Collected Medicinal Orchid In China

“…Traditionally, to obtain the optimal source of fungal mycobionts for symbiotic germination or plant growth, fungi have been isolated and screened from the roots of mature wild plants [26,27]. Among the 28 fungal species reported in 11 D. o cinale studies, only ve fungal species in one study were obtained from protocorms via ex situ seed baiting [28], while the other 23 fungi in the remaining 10 studies were isolated from the roots of wild mature plants, including D. o cinale and other orchid species (Additional le 2). The 28 fungal species/strains, originally obtained from different orchid species and belonging to a wide range of taxonomic groups (17 OMFs and 11 non-OMFs), were found to have positive effects on the growth of D. o cinale seedlings (Additional le 2).…”