摘要
Salinization poses a significant challenge in agriculture, exacerbated by anthropogenic global warming. Biostimulants, derived from living microorganisms or natural extracts, have emerged as valuable tools for conventional and organic agriculture.However, our understanding of the molecular mechanisms underlying the effects of biostimulants is very limited, especially in crops under real cultivation conditions. In this study, we adopted an integrative approach to investigate the effectiveness of the combined application of plant growth-promoting bacterium(Bacillus megaterium strain BM08) and a non-microbial biostimulant under control conditions(normal watering) and salt stress. After confirming the yield increase under both conditions, we investigated the molecular mechanisms underlying the observed effect by measuring a number of physiological parameters(i.e., lipid peroxidation, antioxidants,chlorophylls, total phenolics and phytohormone content), as well as RNA sequencing and primary metabolite analyses. Our findings reveal that the combined effect of the microbial and non-microbial biostimulants led to a decrease in the antioxidant response and an up-regulation of genes involved in cytokinin biosynthesis under salt stress conditions.This, in turn, resulted in a higher concentration of the bioactive cytokinin, isopentenyladenosine, in roots and leaves and an increase in γ-aminobutyric acid, a non-proteic amino acid related to abiotic stress responses. In addition, we observed a decrease in malic acid, along with an abscisic acid(ABA)-independent up-regulation of SR-kinases, a family of protein kinases associated with abiotic stress responses. Furthermore, we observed that the single application of the non-microbial biostimulant triggers an ABA-dependent response under salt stress;however, when combined with the microbial biostimulant, it potentiated the mechanisms triggered by the BM08 bacterial strain. This comprehensive investigation shows that the combination of two biostimulants is able to elicit a cytokinin-dependent response that may explain the observed yield increase under salt stress conditions.
基金
funded by the CDTI program project EXP 00137666/IDI-20210456 awarded to Caldic Ibérica S.L.
the research contract: “Desarrollo de formulados bioestimulantes y biofertilizantes innovadores de origen natural (Calbio) destinados a la agricultura convencional y ecológica. Estudio científico de efectos sinérgicos entre bioactivos microbianos y no microbianos” between Caldic Ibérica S.L. and Universitat Politècnica de València
also funded by the research project CPP2022-009965 “Modelo de evaluación de efectos de bioestimulantes en cultivos con condiciones de stress abiótico: escasez de agua y baja fertilización (MODELCALBIOSTRESS)” funded by MCIN/AEI/ 10.13039/501100011033
the “European Union Next Generation EU/PRTR”
PAID-06-22 “Evaluación del efecto beneficioso de la combinación de diferentes bioestimulantes comerciales (extractos de productos naturales y microbianos) bajo condiciones de estrés salino en plantas de interés agronómico” funded by the Universitat Politècnica de València。
