The effect of smoke derivatives and carbon utilisation on symbiotic germination of the endangered Pterostylis despectans

Abstract

Orchids are highly dependent on exogenous nutritional sources and mycorrhizal associations to survive, particularly when challenged by extreme environmental stress such as bushfires that contribute significantly to its decline in nature. In this study, the effect of smoke derivatives and carbon utilisation was explored to improve germination and seedling establishment of an Australian endangered orchid, Pterostylis despectans (Lowly Greenhood) and its mycorrhizal fungi. Stored seeds were germinated in vitro with pelotonisolated fungal isolates with varying concentrations of smoke water (0-1.0 mL L-1) to simulate fire and sucrose as the carbon source (10 g L-1). Smoke water significantly increased germination, with advanced protocorms and robust seedlings produced. Sucrose inhibited germination such that protocorms and leafing was absent with sucrose inclusion. Fungal isolates were highly variable on its germination efficacy and tolerance to smoke water, highlighting the importance of fungal diversity and supports research-based conservation strategies to circumvent environmental challenges.

Propagation and cultivation practices of honeybush (Cyclopia spp.) for the sustainable production of an export quality indigenous South African tea

“…Studies found that smoke water with its active ingredient as butenolide, 3‐methyl‐2 H ‐furo[2,3‐ c ]pyran‐2‐one, affected a wide range of plant processes. These include increased germination rate (Brown, 1993), stimulation of root initiation and the development of the hypocotyl (Taylor & Van Staden, 1996), promoting the growth rate of seedlings (Sprag et al., 2006), enhancing flowering in geophytes (Bean, 1962), offering seed protection against microbial attacks (Parmeter & Uhrenholdt, 1975; De Lange & Boucher, 1990; Ritmejerytė et al, 2018), and enhancing seedling survival rate (Brown & van Staden, 1997; Elsadek et al., 2019). The South African National Biodiversity Institute (SANBI) recommends smoke primers to promote the propagation by seed of a range of plants with their origins within the fire‐driven fynbos biome, including species from Protea , Leucadendron , Leucospermum , and Erica (Brown, 1993; Brown et al., 1993; Brown & van Staden, 1997; Laurie & Perrier, 2007).…”

The impacts of inter- and intra-seasonal burns on the terrestrial orchid Pterostylis curta

“…Similarly, the components of re driving impacts is also often assumed. For example smoke, which is known to stimulate owering and seed germination in many plant species including orchids (Dixon et al 1995;Ritmejerytė et al 2018), it is thought to be the contributing factor seen in increased vegetative growth in Pterostylis revoluta (Jasinge et al 2018b). However, despite these assumptions, little research has been conducted on excavated tagged orchid individuals to interpret response to re and similarly few studies have tested separate re components.…”