Microorganisms between Plant Protection and Biostimulation Joerg Geistlinger Hochschule Anhalt Anhalt University of Applied Sciences Institute of Bioanalytical Sciences Focus of the TlkTalk: Vital Microbial Inoculants Applied in Agricultural Practice Plant beneficial bacteria and fungi Definition Biostimulant: Plant biostimulants are any (substances or) microorganisms applied to plants with the aim to enhance nutrition efficiency, abiotic stress tolerance and/or crop quality traits, regardless of its nutrients content. Plant biostimulants stimulate natural processes in planta! Biostimulation Features • Growth promotion, incl. root growth (lateral root development) Enhanced nutrition efficiency Hormonal effects, hormone‐like (bioactive) compounds • Abiotic stress tolerance (droug ht/floo d, salt/osmo tic, ht/ldheat/cold, heavy metltal, phthoto, oxida tive ) • Enhanced crop resilience/vigor • Early flowering, enhdhanced flowering • Crop quality maximization (value‐adding ingredients) • Post‐harvest traits (extended shelf‐life, decay delay, foraging capacity) Definition Biocontrol Agents The control of one organism by another. Biocontrol agents are living ()(micro)organisms protecting plants against their enemies, i.e. reducing the population of pests or diseases to acceptable levels. Biocontrol Features • AtibiiAntibiosis –anti‐mibilicrobial meta bo lites (t(antagon ism ) • Competition –for space (occupying ecological niches) for macro/micro nutrients for Iron (chelators, siderophores) • Parasitism –myco‐parasitism (antagonism) bacterial (Actinomycetes) fungal (Trichoderma spp.) • Induced Systemic Resistance (ISR) –cell walls (callose, lignin, phenolics) enzymes (chitinase, peroxidase, polyphenoloxidase, PAL) small molecules (phytoalexines) Conflicting Contents Biostimulation • Abiotic stress tolerance (mediated by plant signaling cascades) via perception of bioactive substances induction/release of signaling compounds Biocontrol • Induced Systemic Resistance (mediated by plant sigggnaling cascades) via perception of bioactive substances induction/release of signaling compounds Overlap Term: Broad‐spectrum resistance pathogens, insects and/or nematodes but also against abiotic stresses • Multiple‐stress responsive genes • Shared responses in major biotic and abiotic stress pathways • Biotic and abiotic crosstalk in several gene networks Plant signaling pathways consist of complex networks with frequent crosstalk, allowing plants to regulate both abiotic stress tolerance AND disease resistance. Convergence Points Abscisic Acid (ABA) – abiotic stress response Jasmonic Acid (JA), Salicylic Acid (SA), Ethylene (ET), Hypersensitive Reaction (HR) Reactive Oxigen Species (ROS) –biotic stress response Respiratory burst oxidase homolog (rboh), required for ROS production induces ABA and HR crosstalk point Enhanced response to ABA 3 (era3) allelic to ethylene insensitive 2 (ein2) intersection in ABA and ET signaling crosstalk point Jasmonate insensitive 1 (jin1) allelic to MYC2 transcription factor (tf) Low MYC2 enhances JA/ET pathogen responses crosstalk point MYB2 (tf) highly homolog to Botrytis susceptible 1 (bos1), mediated by JA bos1 mediates biotic and abiotic stress sigggnaling via ROS crosstalk point NAC RD26 (tf) induced by JA, H2O2, pathogens, also by drought, salt, ABA functions in pathogen defense, senescence, ABA signaling crosstalk point Convergence Points MAPK (mitogen‐activated protein kinase) cascades include multiple stress responses MKK2 –MPK4/6 cascade involved in cold and salt stress signaling MKK4/5 –MPK3/6 cascade regulates pathogen defense via WRKY22/29 (tf) MPK3/6 also induced by abiotic stress (via ABA) crosstalk point MPK6 – induces ET production via ACC (aminocyclopropan 1 carbocylic acid) synthase induces JA‐dependent root growth and MYC2 expression crosstalk point activates ROS sigggnaling via serine/threonine kinases crosstalk point inducible by H2O2 and ABA crosstalk point OsMPK5 ortholog to AtMPK3, induced by ABA and infection in rice crosstalk point Total: 417 genes Venn Diagram Transcriptomics in Cicer arietinum Why should microbial biostimulants that activate multiple biotic and abiotic stress pathways for enhanced broad‐spectrum crop resistance be classified as (bio)pesticides ? Biocontrol What we got….. Bacterial Biocontrol Agents Genera: Bacillus, Pseudomonas, Burkholderia, Serratia, Streppytomyces, Actinoplanes, Stenotrophomonas, Paenibacillus, Klebsiella, Alcaligenes, Pantoea, Ralstonia… Competition for nutrients and space (root niches, root adhesion) motility, chemotaxis, detox. antimicrobial root compounds root exudates and mucilage (sugars, organic acids, amino acids) Alleloppyathy/Allelochemicals: Iron‐chelating siderophores, antibiotics, biocidal volatiles, antifungals Antibiosis: amphisin, oomycin, phenanzine, oligomycin, zwittermicin, tensin….. Lytic enzymes, cell wall hydrolases Detox/degradation: antibiotics, phytotoxine produced by pathogens ISR/Priming: flagellin, siderophores, lipopolysaccharide, volatiles induce plant defense chemicals (callose, phenolics, lignin, phytoalexins, lytic enzymes, PR‐proteins) Bacteria for Biostimulation Genera: Rhizobium, Pseudomonas, Bacillus, Paenibacillus, Bredybacillus, Rhanella, AbAzotobacter, Azospi r illum, Kle bs ie lla, AiAcineto bacter, ShStenotrophomonas, SiSerratia… Growth promo: N2‐fixation, nutrient solubilization (P), auxin and IAA production, ACC deaminase production, ammonia, HCN, siderophores, mycorrhiza helper functions Abiotic stress tolerance: Bacterial auxin, IAA and SA production Decreased heavy metal toxicity Micro‐nutrient mobilization Fungal Biocontrol Agents Genera: Trichoderma, Talaromyces, Cladorrhinum, Idriella, Penicillium, Chaetomium, Minimedusa, Coniothyrium… avirulent Fusarium, Rhizoctonia and Phialophora strains Competition for nutrients and space (infection sites) Antibiosis: Gliovirin, Gliotoxin, Glucose‐Oxidase (H2O2 production) Mycoparasites: Trichoderma, Leucosporidiella, Platygloea, Rhodotorula, Sporidiobolus ISR: avilirulen tstitrains, TihTricho derma, Peni c illium Effector molecules (elicitors): xylanase, oligogalacturonide, chitosan Fungi for Biostimulation Genera: Trichoderma, Glomus (AMF), endo/ekto‐mycorrhizal fungi, endophytes... Abiotic stress tolerance: Sebacina, Piriformospora, Neotyphodium, Trichoderma, Curvularia, Acremonium mainly salt, drought and cold stress ‐ titrigger ing stress response systems in pltlants ‐ produce anti‐stress chemicals (osmolyte, loline, sugar/alcohols) oxidative stress: ROS / RNS detox., antioxidants Plant growth promotion: Neotyphodium positively influences photosynthetic CO2 fixing in host plants Piriformospora produces cytokinine Paecilomyces produces IAA and gibberelline Overlaps again Bacteria in biocontrol and biostimulation Bacillus , Pseudom on as, Paenibac illus , Klebsie lla , Serra tia , SSeteno trop opohom on as Fungi in biocontrol and biostimulation Trichoderma, Penicillium – mycorrhiza and endophytes Should competition really be a biocontrol trait ? Regulation, Legislation Microorgan isms shldhould be iden tifie d at the stitrain lllevel (not always easily d!done!) postulating that most biological activities are strain‐specific (right or wrong?) Biostimulants should be defined according to the intended agricultural outputs nutrient efficiency may cover nutrient mobilization, uptake, transport, storage, assimilation but also root development abiotic stress tolerance physical or chemical stressors of non‐biological origin quality ttatsraits may be veeyry ddeseiverse ((ofrom nutri ti on al vauealue to seshelf‐life) Registration is possible under national fertilizer legislations or EU PPP regulation Why not register under the EU fertilizer laws ? Impossible, BIOSTIMULANTS cannot be fertilizers under EU legislation ! Here, fertilizers are clearly defined: • Provide nutrients for plants • Primary nutrients: NPK • Secondary nutrients: Ca, Mg, Na, S • Micro‐nutitrient s: boron, cobltbalt, copper, iron, manganese, molbdlybdenum, zinc excl. inorganic materials (exception: chelating or complexing agents) All microorganisms that interact with plant physiology must be registered under the PPP regulation, even if they do not protect plants from pests or diseases. Currently no harmonized frameworks are existing neither in the EU, nor in the US EC regulation No 1107/2009 on plant protection products (()‘PPPs’) is applicable to all categories of biostimulants and biocontrol agents, considering a very broad definition of PPPs. Lengthy and costly procedure to place a PPP on the European market. Alternative: The national fertilizer legislations ! BCA Market Top Players BASF Syngenta Bayer CropScience Biologics DuPont Novozymes Koppert Biological Systems Monsanto Company Marrone Bio Innovations Biobest Certis USA Andermatt Biocontrol The BCA market is expected to reach 3 billion USD by 2020 (1. 7 b. USD in 2015) growth rate > 10%, approx. 4% of the global pest control market Comparable to BCA market: 1.7 to 3.0 billion USD Due to the lack of acceptance of biostimulant concepts, market data are of limited reliability. The regulatory status of biostimulants is diverse, depending on registration as fertilizer or pesticide, authorized or not in organic production. Biostimulants may be spread over many regulations, without being named as such. Conclusions • Overlaps exist between Biostimulation and Biocontrol biotic/abiotic stress responses, ISR microbial genera/species/strains applied • Traditional definition of Biocontrol is narrow and precise (implies direct interaction) definition