Evidence of Symbiosis Between the Soil Yeast Cryptococcus laurentii and a Sclerophyllous Medicinal Shrub, Agathosma betulina (Berg.) Pillans

Abstract

The interaction between a common soil yeast, Cryptococcus laurentii, and a slow-growing medicinal plant adapted to low-nutrient soils, Agathosma betulina (Berg.) Pillans, was studied. C. laurentii CAB 578 was isolated from the rhizosphere of wild A. betulina, and liquid chromatography-tandem mass spectrometry (LC-MS-MS) analysis revealed that the yeast was capable of producing polyamines, such as cadaverine and spermine, while growing in vitro in a chemically defined medium. Since the exogenous application of polyamines are known to impact on root growth, these findings supported the results obtained when axenic cultures of A. betulina seedlings were inoculated with C. laurentii CAB 578 and cultivated for 5 months under glasshouse conditions. The presence of the yeast increased root growth by 51%. Using soil dilution plates, it was demonstrated that yeast numbers were greater in the vicinity of the roots than in the bulk soil. In addition, fluoromicroscopy, in combination with the fluorescent probes Fungolight and Calcofluor white, revealed the presence of metabolic active yeast colonies on the rhizoplane 5 months after initiation of the experimentation. The study provided evidence for a symbiosis between C. laurentii and A. betulina.

Physiological responses of seaweeds extracts, benzyl adenine and paclobutrazol of wheat (Triticum aestivum L. Cultivar Misr 1) plants

“…Uniform wheat seeds were planted in natural loamy soil conditions in a plot (12 th groups were treated with (benzyl adenine(200 ppm), paclobutrazol(50ppm). The first group was left aside untreated serving as control.…”

“…of Sci., Al-Azhar Univ., Nasr City, Cairo, Egypt, developed plants were irrigated whenever required. Concentrations of the used yeast extract, arginine and vitamin B 12 were chosen according to a preliminary experiment in which they caused a maximum germination percentage. The plants were sprayed twice with the above mentioned treatments, the first and second were added at 33 and 70 days of plant age respectively.…”

Temperature, pH and carbon source affect drastically indole acetic acid production of plant growth promoting yeasts

“…Yeasts are unicellular fungi that can also be found in the rhizosphere of plants, but in smaller numbers compared to bacteria and filamentous fungi; however, little information is known about their function in this ecosystem. A wide variety of yeasts present characteristics that promote plant growth (Cloete et al, 2009;Limtong et al, 2014;Nutaratat et al, 2014) via the control of plant pathogens (El-Tarabily, 2004;El-Tarabily and Sivasithamparam, 2006;Korres et al, 2011;Rosa et al, 2010), the production of phytohormones (Nassar et al, 2005), the solubilization of phosphate (Hesham and Mohamed, 2011;Falih and Wainwright, 1995;Mirabal Alonso et al, 2008;Mundra et al, 2011), the oxidation and mineralization of nitrogen and sulfur compounds (Falih and Wainwright, 1995), the production of siderophores (Sansone et al, 2005) and the stimulation of root colonization by mycorrhizal fungi (Mirabal Alonso et al, 2008;Vassileva et al, 2000).…”

Characteristics of metal-tolerant plant growth-promoting yeast (Cryptococcus sp. NSE1) and its influence on Cd hyperaccumulator Sedum plumbizincicola

“…This mechanism needs to be explored further to provide definite details. While eukaryotic species, such as Cryptococcus sp., have been shown to assist phytoremediation and possess antifungal activities (Cloete et al 2009), plant growth promotion has typically been investigated using rhizosphere-associated PGP bacteria. Yeasts possess analogous beneficial bioactivity to PGP bacteria (Agamy et al 2013) and have to date been relatively under investigated.…”

“…Yeasts are unicellular fungi which can proliferate rapidly on simple carbohydrates (Mukherjee and Sen 2015). Yeasts have shown adaption to environmental niches including an ability to colonize the rhizosphere in association with plant roots (Amprayn et al 2012;Botha 2011;Cloete et al 2009). A diverse range of yeasts have been reported to exhibit plant growth-promoting characteristics, including phosphate solubilization (Alonso et al 2008;Falih and Wainwright 1995), siderophore production (Sansone et al 2005), phytohormone production (Nassar et al 2005), pathogen inhibition (El-Tarabily and Sivasithamparam 2006;Sansone et al 2005), N and S oxidation (Botha 2011) and stimulation of mycorrhizal-root colonization (Alonso et al 2008).…”