Root colonization by Piriformospora indica enhances grain yield in barley under diverse nutrient regimes by accelerating plant development

Abstract

The basidiomycete fungus Piriformospora indica colonizes roots of a broad range of mono-and dicotyledonous plants. It confers enhanced growth, improves resistance against biotic and tolerance to abiotic stress, and enhances grain yield in barley. To analyze mechanisms underlying P. indica-induced improved grain yield in a crop plant, the influence of different soil nutrient levels and enhanced biotic stress were tested under outdoor conditions. Higher grain yield was induced by the fungus independent of different phosphate and nitrogen fertilization levels. In plants challenged with the root rot-causing fungus Fusarium graminearum, P. indica was able to induce a similar magnitude of yield increase as in unchallenged plants. In contrast to the arbuscular mycorrhiza fungus Glomus mosseae, total phosphate contents of host plant roots and shoots were not significantly affected by P. indica. On the other hand, barley plants colonised with the endophyte developed faster, and were characterized by a higher photosynthetic activity at low light intensities. Together with the increased root formation early in development these factors contribute to faster development of ears as well as the production of more tillers per plant. The results indicate that the positive effect of P. indica on grain yield is due to accelerated growth of barley plants early in development, while improved phosphate supply-a central mechanism of host plant fortification by arbuscular mycorrhizal fungi-was not observed in the P. indica-barley symbiosis.

Piriformospora indicamycorrhization increases grain yield by accelerating early development of barley plants

“…15 This is in line with earlier experiments showing that P. indica is not inducing a significant increase of leaf P and N content in the dicotyledonous plant Nicotiana attenuata, 16 but different from recent results obtained with maize.…”

“…15 Interestingly, P. indica-induced growth promotion is not resulting in higher straw yield to grain yield ratio or taller plants, nor higher contents of mineral nutrients at the end of the vegetative phase, indicating that the host plant is able to control its growth pattern and development during the symbiotic relationship. However, improved early nutrient status promoting tiller formation, and an earlier resource allocation to the ears for the production of grains together with a higher capacity for producing assimilates leads to a higher grain yield.…”

“…This initial advantage of colonized plants could be the basis for a more vigorous development of the shoot (as observed from 2.5 weeks after inoculation in barley) and an improved physiological status leading to the initiation of more tillers (which starts from about 4-5 weeks after inoculation). In addition, the observed enhanced photosynthetic rates of colonized plants 15 contribute to this improved status.…”

“…This hypothesis could not be confirmed: elevated pathogen pressure by applying the necrotrophic fungus Fusarium to the soil did not result in a significantly changed yield effect of P. indica. 15 Therefore, enhanced biotic stress resistance alone can't explain the observed grain yield increase.…”

Profundae diversitas: the uncharted genetic diversity in a newly studied group of fungal root endophytes

“…Endophytes can have several functions and/or may change function during their life cycle (Murphy et al 2013, 2014a). Benefits to crop plants infected with endophytic fungi include an increase in seed yield (Achatz et al 2010; Murphy et al 2014b, 2015), enhanced resistance to pathogens and herbivores (Cheplick and Faeth 2009; Murphy et al 2015a) and increased stress tolerance (Waller et al 2005; Rodriguez et al 2009). …”