Endophyte-Mediated Effects on the Growth and Physiology of Achnatherum sibiricum Are Conditional on Both N and P AvailabilityReportar como inadecuado

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The interaction of endophyte–grass associations are conditional on nitrogen N availability, but the reported responses of these associations to N are inconsistent. We hypothesized that this inconsistency is caused, at least in part, by phosphorus P availability. In this experiment, we compared the performance of endophyte-infected EI and endophyte-free EF Achnatherum sibiricum subjected to four treatments comprising a factorial combination of two levels of N N+ vs. N−, i.e. N supply vs. N deficiency and two levels of P P+ vs. P−, i.e. P supply vs. P deficiency availability. The results showed that A. sibiricum–Neotyphodium associations were conditional on both N and P availability, but more conditional on N than P. Under N+P− conditions, endophyte infection significantly improved acid phosphatase activity of EI plants, such that the biomass of EI plants was not affected by P deficiency i.e. similar growth to N+P+ conditions, and resulted in more biomass in EI than EF plants. Under N−P+ conditions, biomass of both EI and EF decreased compared with N+P+; however, EI biomass decreased slowly by decreasing leaf N concentration more rapidly but allocating higher fractions of N to photosynthetic machinery compared with EF plants. This change of N allocation not only improved photosynthetic ability of EI plants but also significantly increased their biomass. Under N−P− conditions, EI plants allocated higher fractions of N to photosynthesis and had greater P concentrations in roots, but there was no significant difference in biomass between EI and EF plants. Our results support the hypothesis that endophyte–grass interactions are dependent on both N and P availability. However, we did not find a clear cost of endophyte infection in A. sibiricum.

Autor: Xia Li, Anzhi Ren , Rong Han, Lijia Yin, Maoying Wei, Yubao Gao

Fuente: http://plos.srce.hr/


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