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Understanding algee is crucial for developing sustainable farming practices to build a productive farming ecosystem

1. ECOLOGY, DIVERSITY AND BIO-SECURITY OF ALGAL PATHOGENS IN CROP PLANTS SUBMITTED TO : PRESENTED BY : Department of Plant Pathology Dibyasha Jena 211222206 M.Sc. (Ag), 2 nd Year MASTER’S SEMINAR (PL. PATH- 591) (1+0)

2. outline Introduction Algae in Crop Health and Productivity Algal Pathogens , Morphology and Phylogenetic Relationship Diversity of Algal Pathogens Ecology of Algal Pathogens Disease Spread and Transmission Bio-security Measures Case Studies Future Challenges Future Prospects , Future Trends and Technologies in Crop Bio-security Conclusion References

3. INTRODUCTION Crop plants : Backbone of agriculture, Foundation of our global food supply and play a pivotal role in sustaining human life. Algae : Play a significant and multifaceted role in crop health and productivity . Understanding their significance is crucial in addressing the challenges of developing sustainable farming practices to build a productive farming ecosystem.

4. ALGAE IN CROP PLANTS DEFINITION : Algae are a diverse group of photosynthetic organisms. Found in a wide range of environments Possess ability to harness light energy and convert it into chemical energy through photosynthesis

5. PRESCENCE OF ALGAE IN CROP ECOSYSTEMS : Here are some ways in which algae may be found in crop ecosystems: 1. Soil Algae : Inhabits the topsoil in crop fields Contributes to soil health by cycling of nutrients and improving soil structure

6. 2. Irrigation Systems : Proliferate in irrigation canals and ponds used for crop irrigation Nutrient-rich water can promote algal growth. 3. Hydroponics : May be intentionally cultivated in hydroponics systems where they provide additional nutrients for crop plants.

7. 4. Crop Residues : After heavy rain or flooding, algae from nearby water bodies may be deposited on crop fields, affecting crop health and growth. 5. Greenhouse Environments : Establish themselves in greenhouse environments, especially in areas with high humidity

8. ALGAE IN CROP HEALTH AND PRODUCTIVITY 1. Nutrient Supply : Efficient at nutrient uptake and accumulate essential nutrients 2. Biofertilizers : Blue-green algae (cyanobacteria) can fix atmospheric nitrogen, converting it into mobile form. Example : Anabaena azollae in rice 3. Improved Soil Structure : Decompose organic matter of soils which enhances soil structure

9. 4. Stress Tolerance : Produce substances like phytohormones, vitamins, and amino acids that enhance plant stress tolerance 5. Enhanced Photosynthesis : High photosynthetic efficiency due to their chlorophyll content 6. Disease Suppression : Release compounds that inhibits the growth of plant pathogens like fungi and bacteria. FIG : ALGAE IN STRESS TOLERANCE

10. ALGAL PATHOGENS 1. TYPES OF ALGAL PATHOGENS : Can be algae or closely related organisms which are water molds like Saprolegnia, etc. Examples : Cephaleuros virescens (Red rust on crops like tea, coffee, etc) Cephaleuros parasiticus (Green algal spot of citrus)

11. 2. INFECTION AND DISEASE SYMPTOMS : Penetrate tissues through wounds or natural openings like stomata Disease symptoms : Leaf spots, discoloration, wilting, stunted growth and reduced crop quality . In severe cases - defoliation or even plant death.

12. 3. IMPACT ON CROP YIELD : Reduces crop yield by interfering with photosynthesis, nutrient uptake and water transport in infected plants Cause crop deformities, rendering the produce unmarketable

13. EXAMPLES OF COMMON ALGAL PATHOGENS 1. Cephaleuros virescens ( Green Leaf Spot Algae ): Host Plants : Tea, coffee, rubber, other tropical and subtropical crops Symptoms : Circular to irregular red or orange lesions on leaves, stem and fruits. These lesions can lead to leaf drop, reduced photosynthesis and overall plant stress.

14. 2. Cephaleuros parasiticus ( Green Algal Spot ): Host Plants : Citrus trees ( Citrus spp.) and other fruit trees Symptoms : Circular green spots with a black border on leaves, fruits and stem. Infected fruit may be unmarketable and defoliation can occur in severe cases.

15. MORPHOLOGY of cephaleuros spp . Possess branched filaments in form of irregular discs Sporangiate -lateral consisting of zoosporangium and a “ suffultory ” cell Thallus : grow below cuticle or epidermis of host plant Haustorial cells : Present Sporangiophores bear one or more head cells Gametangia : Terminal or intercalary Both sexual and asexual reproduction occurs

16. FIG: ZOOSPORANGIUM(z) BORNE AT END OF A CROOKED “SUFFULTORY” CELL( sc )

17. PHYLOGENETIC RELATIONSHIP

18. DIVERSITY OF ALGAL PATHOGENS 1. Cephaleuros virescens ( Rust Algae ): Responsible for diseases known as algal rusts. Affect tropical and subtropical crops such as tea, coffee, rubber and citrus. Forms characteristic reddish or greenish lesions or blister-like structures on leaves, stem and fruits

19. 2. Cephaleuros parasiticus : Plant pathogenic member of the chlorophyta , or green algae Infects commercial crops including tea causing red rust Appearance of red or orange spots on leaves , leading to premature leaf drop, reduced photosynthesis and weakening of the host plant .

20. 3. Cephaleuros diffusus : The first noted algal disease in Artocarpus incisus (breadfruit) from Kerala, India Leaf spots on the upper leaf surface are visible as orange areas Plant tissue of the affected region gets withered and dies beneath the algal spots

21. 4. Cephaleuros minimus : Common leaf spot disease of Noni (Indian Mulberry) in American Samoa Characterized by light brown color spots surrounded by a conspicuous yellow halo Favored by wet and humid weather

22. 5. Cephaleuros biolophus : Main host : Myrica rubra (Chinese bayberry) Symptoms : Circular purple-black spots about 3-5mm diameter Necrosis of epidermal cells

23. ECOLOGY OF ALGAL PATHOGENS 1. Climate and Weather Conditions : Wet and humid conditions favor the proliferation of algal pathogens . 2. Host Plant Susceptibility : Some crops have genetic resistance or tolerance to specific pathogens, while others are highly susceptible. 3. Crop Density and Arrangement : Crowded plantings create microclimates with higher humidity , promoting disease spread. 4. Irrigation and Drainage Practices : Excessive moisture can create favorable conditions for algal pathogens.

24. 5. Vector Presence : Relies on vectors like insects for spore dispersal which influence disease spread 6. Climate Change and Global Trends : Influences the distribution and prevalence of algal pathogens. 7. Geographical Location : The geographical location of a crop farm , local climate, host species and land use practices impact disease ecology.

25. DISEASE SPREAD AND TRANSMISSION 1 . Rain Splash : Dislodge algal spores from infected plants to healthy plants, leading to new infections Common in algal pathogens causing leaf spot diseases . 2 . Wind Dispersal : Significant for pathogens that cause diseases in crops with expansive canopies, such as cereals and grasses

26. 3. Insect Vectors : Aphids and whiteflies are known vectors for some algal pathogens. 4. Seed-borne and Soil-borne Transmission : Seed-borne transmission : through seeds Soil-borne transmission : by contaminated, farm equipment or soil amendments. 5. Human Activity : Farm operations can spread algal pathogens. 6. Infection Courts : Create specialized infection courts or structures on host plants to facilitate entry such as appressoria

27. STRATEGIES FOR DISEASE CONTROL AND PREVENTION 1 . Crop Rotation : Rotation of crops with non-host plant species 2 . Resistant Crop Varieties : Selection and planting of crop varieties resistant to specific algal pathogens 3. Sanitation: Removal and destruction of infected plant material Use of clean farming equipment

28. 4. Vector Management : Implementation of vector control measures if insects serve as disease vectors 5. Irrigation Management : Avoidance of overhead irrigation Use of minimal irrigation practices 6. Biological Control : Use of natural enemies or antagonistic microorganisms that can suppress algal-pathogen populations.

29. BIO-SECURITY MEASURES IMPORTANCE OF BIO-SECURITY IN AGRICULTURE : 1 . Disease Prevention and Control : Prevents the introduction and spread of infectious diseases caused by bacteria, viruses, fungi, etc. 2. Food Security : Helps to maintain stable food supplies by preventing disease-related crop losses

30. 4. Environmental Conservation : Prevents the spread of invasive diseases into crop habitats, helping to preserve biodiversity 5. Sustainable Agriculture : Reduces the need for chemical treatments, minimizing environmental contamination and promoting ecological balance 6. Global Trade Facilitation : Prevents the inadvertent transfer of pathogens across borders

31. WAYS TO IMPLEMENT BIO-SECURITY MEASURES AGAINST ALGAL PATHOGENS 1. Pathogen-Free Planting Material : Use of disease-free seeds or planting material 2. Quarantine and Isolation : Establishment of quarantine zones Isolation of newly acquired plants from the main crop until they are confirmed disease-free. 3. Sanitation : 4. Crop Rotation : Crop rotation with non-host crop species

32. 5. Resistant Varieties: Use of crop varieties that have demonstrated resistance to algal pathogens. 6. Plant Density and Spacing : Optimization of plant spacing and density within the сгор сапору 7. Irrigation Management : Use of drip irrigation or other methods that avoid wetting the foliage 8. Monitoring and Early Detection : Inspection of crops for symptoms of algal diseases

33. 9. Vector Control : Management of vectors like insects that can transmit algal spores 10. Biological Control : Utilization of biological control agents that can suppress algal pathogen populations 11. Biosecurity Plans : Development and implementation of a comprehensive biosecurity plan tailored to specific crop and disease risks

34. FUTURE CHALLENGES Here are some key challenges that researchers and farmers may face in the management of algal pathogens: 1. Emerging Pathogens : Emergence of unidentified algal pathogens, requiring ongoing surveillance and research 2. Antifungal Resistance : The potential development of resistance in algal pathogens to fungicides

35. 3. Climate Change : Alters the distribution and behavior of algal pathogens leading to new disease outbreaks in new regions 4. Data Management : Requires advanced data management and analytics capabilities. 5. Resource Constraints : Small-scale and resource-limited farmers may face challenges in adopting and implementing advanced disease management practices and technologies.

36. FUTURE PROSPECTS 1 . Precision Agriculture : To reduce the need for broad-scale chemical treatments 2. Biological Control with Microbes : Use of beneficial microorganisms that can antagonize algal pathogens. 3. Microbiome Management : Manipulation of plant microbiome to promote the growth of beneficial microorganisms

37. 4. RNA Interference (RNAi) : Utilization of RNAi technology to silence genes in algal pathogens, disrupting their ability to cause disease. 5. Nano-agriculture : Use of nanomaterials for targeted zero delivery of antimicrobial agents 6. Digital Agriculture and Big Data : Leverage data analytics, machine learning and sensor technology to create predictive models for disease outbreaks

38. 7. Volatile Organic Compounds (VOCs): U se of volatile organic compounds emitted by beneficial microbes 8. Nanobubbles for Water Treatment : Use of nanobubbles to treat irrigation water, reducing the risk of pathogen transmission through contaminated water sources. 9. Bio-fumigation : Use of biofumigant cover crops like mustard

39. FUTURE TRENDS AND TECHNOLOGIES IN CROP BIO-SECURITY 1. Advanced Disease Detection : Rapid and high-precision disease detection methods, such as remote sensing, hyperspectral imaging and DNA sequencing 2. Digital Agriculture and Big Data : Use of big data analytics, machine learning and artificial intelligence (Al)

40. 3. Sensor Networks : Enables real-time monitoring of environmental conditions , crop health allowing for timely interventions. 4. Bioinformatics and Predictive Modeling : - Helps in deciphering pathogen genomes and understanding their evolution Predictive models will forecast disease outbreaks and guide control measures.

41. 5. Precision Application of Treatments : Variable rate application systems will enable the precise and efficient application of plant protection chemicals. 6. Drones and Robotics : Used for aerial surveys, crop scouting and targeted chemical application, reducing the need for human labour

42. CONCLUSION Understanding algal pathogens in crop plants, their ecology, diversity, and implementing biosecurity measures is of paramount importance for several compelling reasons: Protecting Global Food Security : To develop strategies to mitigate their impact and ensure a stable food supply for a growing global population. Environmental Stewardship : Studying their ecology helps prevent unintended environmental consequences. Crop Diversity and Resilience: Understanding the diversity of algal pathogens helps in selecting disease-resistant crop varieties. Global Trade and Biosecurity : Global trade in agricultural products necessitates biosecurity measures to prevent the unintentional spread of algal pathogens to new areas.

43. REFERENCES Brooks, F. 2004. Plant parasitic algae ( Trentepohliales , Chlorophyta) in American Samoa. Technical Report no. 39. (Also published in Pacific Science 58 : 419–428, University of Hawai‘i Press). Chapman, V.J, D.J (1975). The Algae . Palgrave Macmillan Holcomb, G.E. 1998. First report of Cephaleuros virescens in Arkansas and its occurrence on cultivated blackberry in Arkansas and Louisiana. Plant Disease  82  :263. Murua Pedro, Garvetto Andrea, Egan Suhelen , Gachon Claire M.M. 2023.The Reemergence of Phycopathology : When Algal Biology Meets Ecology and Biosecurity. Annu.Rev.Phytopathol . 2023. 61 : 231-55 Nelson Scot C. 2008. Cephaleuros Species,the Plant-Parasitic Green Algae. University of Hawai'i at Manoa, College of Tropical Agriculture and Human Resources, Plant Disease no. 43. www.ctahr.hawaii.edu/oc/freepubs/pdf/PD-43.pdf. Round, F. E (1984). The Ecology of Algae . Cambridge University Press