Positive yield and quality results from fungi and bacteria in symbiosis with strawberries

A clearer understanding of the interactions between fungi and bacteria that are beneficial to plants is an essential area relative to sustainable agriculture.? In the context of a thesis project, the Joint Research Unit for Agroecology in Dijon and the Universita Del Piemonte Orientale studied the interactions between the fungus-bacterium couple on strawberry growth and quality.The flavour of strawberries is determined by their sugar and acid contentsStrawberries have a sugar content that at ripeness can reach 500 mg per kg dry weight.? Glucose, fructose and saccharose account for 99% of their total sugar composition.? Sugar levels in strawberries are partly dependent on the FaSUt1 transporter. By inoculating strawberry plants with the fungus-bacterium couple, scientists were able to measure its impacts on the expression of this transporter and the sugar content of fruits.Rhizophagus irregularis: a mycorrhizal fungus that is beneficial to strawberry growthGlomeromycetes, fungi known for their arbuscular mycorrhizal symbiosis, live with a great many plants.? Their effects have been observed not only on root systems but also on leaves, flowers and fruits. Thanks to nutritional exchanges between the fungi and the plant, this symbiosis impacts certain characteristics of fleshy fruits: contents in minerals, amino acids, antioxidants, carotenoids, sugars and volatile compounds.Effect of combining arbuscular mycorrhizae and PGPROver a 2-year period, efforts were made to understand the effect of R. irregularis in the context of natural multitrophic interactions in the rhizosphere on the production and quality of strawberries.? Different plant growth promoting rhizobacteria (PGPR) were tested under semi-controlled conditions.? The results revealed the beneficial effects on fruit yield and quality of the concomitant inoculation of R. irregularis and Pseudomonas fluorescens Pf4. Sugar distribution in fruits: mechanisms and molecular actorsTo understand the synergistic effects of the fungus-bacterium inoculum on strawberry growth and development, the scientists analysed its impact on the expression of sugar transporters (FaSUTs) in different plant organs.? To achieve this, strawberry? plants (Fragaria x ananassa Duch. Var. Elyana F1) were cultivated with or without inocula.? Between flowering and harvest, the number of flowers and fruits were recorded three times a week.? The ripe fruits were weighed, measured and analysed biochemically (pH, sugar content).Promising results for inoculum producersThe statistical tool showed that the fungus exerted a positive effect on the vegetative development of strawberry plants, while the bacterium acted on fruit yield and quality.? It is now necessary to determine the ideal combinations necessary under different cultivation conditions (in the field, under semi-controlled or controlled conditions, etc.) that will be able to optimise the flavour and quality of strawberries while sustaining high yields.? The Joint Research Unit for Agroecology wishes to pursue this work through consumer tests in partnership with the Centre for Taste, Food and Nutrition Sciences (CSGA) in order to validate the effects on product quality.Scientific contact(s):Daniel Wipf (03 80 69 34 52) Joint Research Unit for Agroecology (UMR 1347)-Plant-Micro-organism Interactions Cluster-17 rue Sully-21065 DIJONAssociated Division(s):Environment and Agronomy, Plant Health and the Environment, Plant Biology and Breeding?? ?Associated Centre(s):??? Dijon?? ?Find out morePGPR (Plant Growth Promoting Rhizobacteria) are natural rhizobacteria that colonise the roots and contribute to plant growth and health.? In exchange, through its root exsudates, the plant supplies the PGPR with a source of carbon.The bacterial strains used came from Mybasol, an Italian company based in Alessandria and a spin-off of Universita Del Piemonte Orientale, which belongs to Professor Grazielle Berta, the joint supervisor of the thesis project.This company produces and distributes bio-fertilisers and substances that stimulate natural plant defences that are made of a mixed "mycorrhizal fungus-rhizobacterium" inoculum, as well as microbial agents to decontaminate land. http://www.i3p.it/files/III_Mybasol.pdfSourceNassima AIT LAHMIDI, ? Sugar transport and partitionning during arbuscular mycorrhizal symbiosis ?, Th?se, Ecole doctorale Environnements ? Thesis, Environment-Health Doctoral School, Joint Research Unit for Agroecology / INRA 1347/Agrosup /Universit? de Bourgogne, Plant-Micro-organism Interactions Cluster, ERL 6300 CNRS, Universita Degli Studi Del Piemonte Orientale, 20 February 2015, 290 pages.