Evidence that the soil yeast Papiliotrema laurentii affects germination, vigour and grain nutrient content of wheat (Triticum aestivum L.)

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. 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. 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. 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. • The yeast Papiliotrema laurentii CAB 91 improves germination and vigour of wheat. • Yeast polyamine production is implicated in improved wheat germination. • Yeast seed coating can increase grain protein content and grain number per spike. • P. laurentii shows potential to be developed as bio-fertiliser for wheat.