The mycorrhizal fungi ofCymbidiumpromote the growth ofDendrobiumofficinaleby increasing environmental stress tolerance

Abstract

Dendrobium officinale is a medicinal herbal plant with important health care value and high demand. Due to its slow growth and scarcity in nature, its yield depends on intensified cultivation while biotic and abiotic stresses were important factors that causes production loss. Orchidaceae can form association with rhizoctonias collectively, and studies have found that some orchids showed a high level of strain-species specificity to orchid mycorrhizal fungi (OMF), yet the specificity of OMF on D. officinale needs to explored. In this study, the effects on D. officinale of four OMF isolated from Cymbidium were tested. The obviously higher mass yield of the treated plants in medium and pots indicated the growth promotion effect of the fungi. Furthermore, an abiotic stress test indicated stronger drought tolerance among the treated plants. For the biotic stress test, two root rot pathogens, Fusarium solani and Fusarium graminearum , were isolated and identified from root rot of D. officinale. In an in vitro inhibition test, the four OMF could resist the growth of these pathogens. In vivo studies showed that these four OMF could improve the survival rate and fresh weight and decrease the root rot rate of pathogen-inoculated seedlings. The four OMF namely; Hyphomycete sp., Umbelopsis sp., Ceratorhiza sp. and Ceratorhiza sp. are compatible strains for improving the growth rate of D. officinale by increasing its environmental stress tolerance, providing an effective way to supply resources through artificial reproduction.

High endophytic diversity associated with roots of Cattleya milleri, an endemic orchid from rupestrian grasslands of the “Quadrilátero Ferrífero”, a Brazilian savanna hotspot area in Minas Gerais

“…Both mycorrhizal and non-mycorrhizal fungi can help plants during adverse eld conditions, including acclimatisation, drought period, and pathogen infection. Thus, their inoculation is suitable during plant cultivation, especially during the propagation of the species toward reintroduction (Cribb et al 2003;Nogueira et al 2005;Li et al 2021b). Once an orchid is reintroduced in nature with endophytes, both the plant and its symbionts are preserved and reintroduced, which increases the chances of occurrence of natural propagation and the maintenance of the orchid life cycle (Cribb et al 2003 Implementing symbiotic propagation requires culture-dependent studies, where endophytic fungi are isolated, classi ed, and then, used in a co-inoculation test to select appropriate isolates for orchid propagation Valadares 2012, 2017;Tian et al 2021).…”