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Probiotics for plants Harsh Bais Department of Plant & Soil Sciences Plants, like most animals, are multicellular eukaryotes Bacteria Archaea Fungi Animals Plants Common ancestors Photo credits: Public Health Image Library; NASA; © Dave Powell, USDA Forest Service; tom donald Plants are diverse Grasses Ferns Flowering Plants Club mosses Seed Plants Conebearing plants Vascular Plants Plants have evolved the ability to thrive in diverse land habitats. Mosses Liverworts Land Plants Broadleafed plants Green algae Images courtesy tom donald Plants are amazing living organisms Largest organism (> 100m) Largest flower (~ 1m) Longest living (~ 5000 years) But why do we study them? Photo credits: ma_suska; Bradluke22; Stan Shebs The world population grows and grows ... The world population is expected to triple between 1950 (2.5 billion) and 2020 (7.5 billion) The world population grows and grows ... A major objective of plant science is to increase food production; current estimates indicate that we need to increase production by 70% in the next 40 years. Food security is a major global issue Global food shortage is a reality not a myth. Globally, more than one billion people per year are chronically hungry That’s more than the total population of the USA, Canada and the EU. What is the major cause for loss in crop yield ? (Source: FAO news release, 19 June 2009) Environmental stress 65% 60% 45% 55% 8 Plant scientists can contribute to the alleviation of hunger By developing plants that: are drought or stress tolerant require less fertilizer or water are resistant to pathogens are more nutritious What have we done to increase crop productivity. Green revolution and fertilizers: Agricultural fertilizer use is a considerable source of environmental pollution Fertilizer run-off causes dead zones, algal blooms that then decay, reducing oxygen levels in the water and making animal life impossible Other approaches to increase crop yield. Photo courtesy of NASA/Goddard Space Flight Center Scientific Visualization Studio) Other approaches for crop enhancement & protection: Transgenic Time >>>>>> Regulation/approvals>>> Perception -- Conventional breeding Time >>>> Resistance >> BIOLOGICALS Rapid << Low-Resistance << Perception ++ It’s a microbial world The probiotic BOOM! The concept of Good, Bad & Ugly 1. A harmless bacterium that helps to protect the organism from harmful bacteria 2. A substance that encourages the growth of natural healthy bacteria in the organism Gut Microbiome, health & disease 13 Plants Perspective Beneficial plant-microbe interactions Zones to study plant-microbe interactions: • Phyllosphere • Rhizosphere • Endosphere Image courtesy: The Scientist In 1 teaspoon of soil there are… Bacteria 100 million to 1 billion Fungi 6-9 ft fungal strands put end to end Protozoa Several thousand flagellates & amoeba One to several hundred ciliates Nematodes 10 to 20 bacterial feeders and a few fungal feeders Arthropods Up to 100 Earthworms 5 or more For more info: See “Jewels of Jungles” Free living v/s endophytic lifestyles Applications: Agriculture productivity, biomass, biofuel & therapeutics Microbial Biofilms How do plants and microbe interact? Talking trees How do plants communicate? Chemical signals Bacillus Arabidopsis subtilis thaliana Bacillus subtilis forms biofilm on Arabidopsis roots Rudrappa et al. (2007) Planta; Rudrappa et al. (2008) Plant Physiology; Lakhsmanan et al., 2012 Plant Physiology; Laksmanan et al. 2014 Questions Do plants actively recruit beneficial microbes belowground? What are the cause & consequences of beneficial root binding on plant fitness, disease protection and food safety ? What do we know about botanical cry’s in plants Do plants carry both public and private messages? Heil and Bueno, PNAS (2007) Plants Talk. Plants Listen. Here's How 23 How do roots respond upon leaf attack Bacillus binding on roots Pathogen Control Mock 24 Rudrappa et al. (2007) Planta; Rudrappa et al. (2008) Plant Physiology; Lakhsmanan et al., 2012 Plant Physiology; Laksmanan et al. 2014 How belowground beneficial microbes impact phyllosphere microbiome? Pathogens use stomates as entry points Oliamet and Holly 2012, Food Microbiol Pathogen opens the stomata in A. thaliana Kumar A et al. (2012) Plant Journal Bacillus subtilis causes stomatal closure in A. thaliana Control Bacillus-root -3h How does it relate to REAL plants? Bacillus-leaf-3h Kumar A et al. (2012) Plant Journal Bacillus + Pathogen-3h Is my salad safe to eat? Olaimet and Holly 2012, Food Microbiol Foodborne pathogens use stomates as entry points in leafy greens Bacillus subtilis causes stomatal closure in Spinach Bacillus Treated Untreated 3hr pst 3hr pst Other plants traits that can be targeted using BIOLOGICALs Drought Biomass Mock Bacillus Blast infections in Rice Control Infected Other bacterial strains Root architecture in legumes Control Control Bacillus Rice isolate Bacillus treated • • • • Summary Plants actively recruit beneficial microbes belowground under foliar pathogen attack. Beneficial root binding closes entry points restricting foliar pathogen invasion. Stomatal closure by beneficials may have implications to increase food safety in leafy greens. Different traits related to growth, yield and protection against pathogens could be targeted using BIOLOGICALs. Acknowledgments Bais Lab members: Dr. Thimmaraju Rudrappa (Postdoc) Meredith Biedrzycki (Ph.D. student) Dr. Venkatachalam Lakshmanan (Postdoc) Dr. Gurdeep Bains (Postdoc) Dr. Amutha Sampat Kumar (Postdoc) Dr. Deepak Shantharaj (Postdoc) Carla Spence (Ph.D. Student) Emily Alff (M.S. Student) Bhavana S. Agarwal (Ph.D. Student) Amanda Roberson (Ph.D. Student) Dr. Shail Badal (Postdoc) Plant Genome Research Program (NSFPGRP) Collaborators: Sarah Markland (Ph. D Student) (Kniel Lab) Dr. V. Sundaresan and Sundar Lab (UC Davis) Dr. Nicole Donofrio & Donofrio Lab (UD) Dr. Paul W. Pare (Texas Tech. U.) Dr. Kirk Czymmek (Carl Zeiss Co.) Dr. Jeff Caplan (UD) Dr. Kali Kniel (U. Delaware) Dr. Janine Sherrier (UD) Dr. Dan Kearns ( Indiana U.) Dr. Angelia Seyfferth (U. Delaware) Dr. Flavio Mederious (UFLA, Brazil) “While we animals were busy nailing down things like locomotion and consciousness, the plants acquired an array of extraordinary and occasionally diabolical powers by discovering how to synthesize remarkably complicated molecules.” Michael Pollan, Botany of Desire 35