Microbes synthesize a multitude of substances including carbohydrates, proteins, lipids, amino acids, hormones, volatiles, etc., which regulate plant growth and morphogenesis. Irrigation with culture filtrates (CFs) of some plant beneficial microorganisms promotes plant growth and enhances yield. However, nothing is known about the response of plants to soil application of CFs of microbial phytopathogens. In this work we explored the response of two pepper (Capsicum annuum L.) cultivars (i.e. Sweet Italian and Piquillo) and soil microbiota to CFs of the beneficial fungus (i.e. Trichoderma harzianum) and two fungal phytopathogens (i.e. Alternaria alternata and Penicilliun aurantiogriseum). We found that soil application of CFs of the three fungal species similarly enhanced root growth (40-70% increase under greenhouse conditions) and commercial fruit yield (50-112% and 20-28% increase under greenhouse and open field conditions, respectively). High-throughput amplicon sequencing of bacterial 16S and fungal ITS rRNA genes of the soil microbiota revealed that the CF treatments led to strong enrichment of the populations of the same beneficial bacterial and fungal species. Our findings show that the application of microbial CFs to the soil represents a potentially very useful strategy for increasing the yield of horticultural crops in a sustainable and environmentally friendly way

This work was supported by the Agencia Estatal de Investigación (AEI) and Fondo Europeo de Desarrollo Regional (Spain) (grants BIO2013-49125-C2-1- P, BIO2016-78747-P and PID2019-104685GB-100), the Government of Navarra (refs. P1044 AGROESTI, P1004 PROMEBIO and P1046 MICROBIOME), and the Ministry of Education, Youth and Sport of the Czech Republic and the ERDF project “Plants as a tool for sustainable global development” (No. CZ.02.1.01/0.0/0.0/16_019/0000827).

Resumen del trabajo presentado en la XXIV Reunión de la Sociedad Española de Biología de Plantas - XVII Congreso Hispano-Luso de Biología de Plantas, celebrado online del 7 al 9 de julio de 2021