Fungi isolated from host protocorms accelerate symbiotic seed germination in an endangered orchid species (Dendrobium chrysotoxum) from southern China

Shao, Shi-Cheng; Wang, Qiuxia; Beng, Kingly C.; Jacquemyn, Hans

doi:10.1007/s00572-020-00964-w

Cited by 32 publications

(32 citation statements)

References 48 publications

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“…Seedling formation, on the other hand, only occurred under light-dark conditions, and no seedlings were found when seeds were grown under complete darkness. These results support previous findings (Wang et al, 2011;Zi et al, 2014;Huang et al, 2018;Shao et al, 2020) that light, unlike in terrestrial orchids (Rasmussen, 1995), is a prerequisite to induce seedling formation in epiphytic orchids. The highest percentages of seedling formation were observed after 50 days for fungal strains JC-01 and JC-03 (45.26 ± 21.16%, 41.61 ± 26.79%, respectively) under 12/12-h light conditions.…”

Section: In Vitro Symbiotic Seed Germinationsupporting

confidence: 92%

“…In this study, we used in situ baiting techniques to isolate mycorrhizal fungi from protocorms of the epiphytic orchid D. nobile and to induce seed germination under laboratory conditions. This method has been previously used successfully to induce seed germination of epiphytic orchids under in vitro conditions (Wang et al, 2011;Zi et al, 2014;Zhou and Gao, 2016;Shao et al, 2020). Plastic wraps were used to fix the seed packets on tree trunks and to keep the seeds in a humid environment.…”

Section: Discussion Fungi Associated With Protocorms In the Fieldmentioning

confidence: 99%

“…In addition, in vitro experiments have shown that fungi isolated from adult roots may stimulate germination per se, but they do not necessarily support subsequent seedling development (Rasmussen et al, 2015) and in some cases may even result in seedling mortality (Zettler et al, 1999;Rasmussen, 2002). Recent experiments have also shown that fungi isolated from protocorms usually lead to higher germination percentages and seedling establishment than fungi isolated from the roots of adult plants (Zi et al, 2014;Zhou and Gao, 2016;Huang et al, 2018;Meng et al, 2019a;Shao et al, 2020), suggesting that fungi associating with adult plants are not necessarily the fungi that induce germination.…”

Section: Introductionmentioning

confidence: 99%

“…In this study, we compared the in vitro germination success of the epiphytic orchid Dendrobium nobile between monocultures and co-cultures of mycorrhizal fungi. Previous research has shown that fungi isolated from protocorms in the field accelerated seed germination of the related Dendrobium chrysotoxum (Shao et al, 2020). We therefore first used seed baiting techniques to isolate fungi associating with protocorms and constructed monocultures and co-cultures of these fungi to assess germination success in in vitro trials.…”

Section: Introductionmentioning

confidence: 99%

“…Specifically, we hypothesized that (1) fungi isolated from protocorms were able to initiate seed germination and support growth to the seedling stage, and (2) that co-cultures of mycorrhizal fungi significantly increased protocorm formation and seedling development. Because previous research has shown that light conditions can have a large impact on seed germination and seedling formation in epiphytic orchids (Zi et al, 2014;Shao et al, 2020), all experiments were conducted under contrasting light conditions.…”

Section: Introductionmentioning

confidence: 99%

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Co-Cultures of Mycorrhizal Fungi Do Not Increase Germination and Seedling Development in the Epiphytic Orchid Dendrobium nobile

2020

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Orchids are highly dependent on mycorrhizal fungi for seed germination and subsequent growth to a seedling as they provide essential carbon, water, and mineral nutrients to developing seeds. Although there is mounting evidence that orchid seeds are often colonized by multiple fungi simultaneously, most in vitro germination experiments focus on mycorrhizal monocultures and little is known about how mycorrhizal assemblages affect seed germination and growth of seedlings. In this study, we compared the effects of mycorrhizal monocultures and co-cultures on seed germination and seedling growth of the epiphytic orchid Dendrobium nobile. In situ baiting was used to isolate mycorrhizal fungi from protocorms for germination experiments. Germination experiments were conducted under two light regimes for 90 days. In total, five fungal strains were isolated from protocorms of D. nobile, indicating that the species was not highly specific to its fungal partners. Four strains (JC-01, JC-02, JC-04, and JC-05) belonged to the Serendipitaceae and one (JC-03) to the Tulasnellaceae. In vitro germination experiments showed that germination percentages were higher under light-dark conditions than under complete dark conditions, supporting previous findings that light facilitates germination in epiphytic orchids. While all strains were able to induce protocorm formation and growth into the seedling stage, large differences between fungal strains were observed. Co-cultures did not result in significantly higher seed germination percentages and seedling development than monocultures. Taken together, these results demonstrate that effects of fungal assemblages are not predictable from those of component species, and that more work is needed to better understand the role of fungal assemblages determining seed germination and subsequent growth under natural conditions.

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Section: In Vitro Symbiotic Seed Germinationsupporting

confidence: 92%