Purpose The effect of a soil yeast seed coating on germination, growth and crop characteristics of wheat (Triticum aestivum L.) is unknown. Thus we determined the plant growth promoting (PGP) traits of Papiliotrema laurentii CAB 91 before evaluating the effect of the yeast on the germination and vigour of wheat. We then studied the effect of a seed coating containing the yeast on wheat growth, as well as grain morphology and nutrient content under field conditions. Methods We evaluated the PGP properties of P. laurentii CAB 91 and determined the effects thereof on the germination and vigour of three wheat cultivars, namely cv. Ratel, cv. SST027 and cv. SST047. Additionally, the effect of polyamine (PA) production by the yeast on cv. Ratel and cv. SST027 germination was investigated, and the effect of three PAs on the germination of the same two cultivars in the absence of the yeast was determined. Finally, we evaluated the efficacy of a P. laurentii CAB 91 seed coating on growth and grain characteristics of cv. Ratel and cv. SST027 under field conditions. Results The PGP traits of P. laurentii CAB 91 include solubilisation of phosphate and zinc, as well as decarboxylation of amino acids that have been implicated in polyamine production. While the yeast increased the vigour of all three cultivars, and improved germination of cv. Ratel and cv. SST027, no effect was observed on the germination of cv. SST047. Similarly, cv. Ratel and cv. SST027 seeds exhibited improved germination on a medium designed to induce yeast PA production. In the absence of the yeast, it was found that the PA spermidine increased the germination of both cv. Ratel and cv. SST027 seeds. Under field conditions and compared to control plants, cv. SST027 treated with the yeast produced larger spikes with more grains per spike, while both yeast-treated cv. Ratel and cv. SST027 produced grain with increased protein content. Conclusion The findings that a soil yeast seed coating may impact on grain characteristics under field conditions paves the way for the development of affordable and efficacious yeast biofertilizers.

Biochar amendment of soils is an ancient technology which has attracted a lot of recent attention from soil scientists and environmentalists as a possible way to sequester carbon from the atmosphere in the soil, whilst increasing soil fertility. Wheat (Triticum aestivum) was grown for twelve weeks in pots were pine derived biochar was placed in two distinct layers within a sandy soil. The sandy and biochar layers were separated at harvesting to assess plant root growth, microbial biomass and degree of mycorrhizal root colonization. The biochar layers formed preferred zones for root development (P = 0.039) and microbial proliferation (P < 0.001) compared to the sandy layers. However, the degree of root mycorrhizal colonization decreased slightly in the two biochar layers and in the sandy layer between them, relative to the sandy layers above and below. The decrease in mycorrhizal colonization was possibly due to the enhancing effect that biochar has on water and nutrient retention. Furthermore, the physical and chemical characteristics of the biochar layers differed markedly from the sandy layers in terms of pH, cation exchange capacity, total C and available P. These factors have a strong influence on the micro-climate and nutrient status of each layer.

Knowledge of the environmental prevalence of members of the Ctyptococcus neoformans/Cryptococcus gattii species complex is important, since cryptococcal infection is acquired from the environment. We determined whether trees located in two South African recreational areas harboured pathogenic cryptococci and compared the isolates to clinical isolates obtained from Western Cape hospitals with molecular typing techniques. The majority of isolates originating from trees in a public park in Cape Town (PPCT) were C. gattii sensu stricto, followed by C neoformans sensu stricto genotype AFLP1/VNI. The PPCT trees might be a source of infection, since all genotype AFLP1/VNI isolates from these trees and one clinical isolate belonged to the same sequence type (ST), i.e. ST23. Recombination and basidiospore production might be occurring in PPCT trees that contained C gattii s.s. isolates belonging to both mating types. The presence of C gattii s.s. in PPCT trees might therefore pose a risk to human health. (C) 2017 Elsevier Ltd and British Mycological Society. All rights reserved.

The value of healthy forest ecosystems is well known and trees in these systems form symbioses with a variety of living organisms. This review focuses on literature pertaining to the potential interactions of arboreal yeast endophytes with trees and their associated insects. Although very little is known about the symbioses of arboreal yeast endophytes, indications are that some of these unicellular fungi produce plant-growth promoting phytohormones, while others are antagonistic towards phytopathogens or are capable of producing pheromones that affect the behavior of insect herbivores. However, more research needs to be conducted to fully understand the role of arboreal yeast endophytes in ecosystem processes.

The benefits of biological nitrogen fixation (BNF) for blue lupin (Lupinus angustifolius L.) are well known. However, it is unclear how multiple microorganisms, other than plant growth promoting rhizobacteria, affect this legume’s BNF and growth. Therefore, we evaluated the impact of mycorrhizal fungi and a yeast on growth and nutrition of nodulated blue lupin.