1. Mubashir hussain PhD Scholar
13-arid-3282

2. Bio-based resistant inducers for sustainable plant protection against pathogens (Phytochemical pesticides)

3. Contents: Introduction Immune system in plant Resistance inducers
1. Chemical inducers
2. Microbial elicitors
Bacterial elicitors
Fungal elicitors
3. Plant extracts
Algal extracts
Extracts of higher plants
4. Composts
5. Biochar
Conclusion
Reference

4. Introduction
In agriculture, plant varieties were domesticated and over time bred for yield and fruit quality.
Plant disease resistance is often decreased compared to wild varieties
Most plants including crops are susceptible to numerous diseases caused by different microorganisms (pathogens).
Diseases decrease crop yield and quality and toxins released by microbes were usually present in the harvest.

5. Conti….
Formerly, diseases were responsible for severe economic and nutritional crises and are still responsible for a considerable loss in the worldwide crop production.
To date, ensuring a satisfactory yield and the quality of the harvest requires an extensive use of numerous phytochemical pesticides.
Pesticides harm crops, the environment, even the health of farmers and consumers and may lead to selection of resistant pathogen strains.

6. Alternative and sustainable disease management
Alternatives include
Organic and integrated farming practices
Biological control
Use of resistant hybrids or transgenic crops.

7. Limitations
Some national legislative bodies do not allow genetic crop improvement by transgenesis and assisted crossing may also be prohibited for some crops, such as wine, protected by appellation seals.

8. Immune Systems in Plant
Can be broadly classified as;
Local defense system
It is concerned with imparting immunity only at the site of infection.
It is more common than proliferated one.
 Proliferating defense system
Can be Initiated sometimes due to local defense system
Defense alert is amplified and transferred from the site of infection by a system of mobile signals into distal (systemic) plant parts.

9. IMMUNE SYSTEMS IN PLANT Proliferative defense system
Systemic acquired resistance (SAR)
Induced systemic resistance (ISR)
Local defense system
Hypersensitive response (HR)
Effector-triggered immunity (ETI)
MAMP/PAMP/pattern-triggered immunity (MTI/PTI).

10. Immune system in plants
Step 1: Attack of non-self” signals
Microbe/pathogen-associated molecular patterns (MAMPs/PAMPs) are conserved molecular structures essential for the overall fitness of microbes
b) Host derived “danger” signals or damage-associated molecular patterns (DAMPs), such as pectin-derived oligogalacturonides, produced as a consequence of enzymatic microbial activities and toxins.

11. Conti..... Step 2: Recognition of foreign material
MAMPs and DAMPs are recognized by plasma-membrane localized pattern recognition receptors (PRRs) and induce a broad variety of defense responses commonly referred to as MTI or PTI.

12. Conti..... Step 3: initial cascade of signaling events
Tiggers ion fluxes leading to plasma membrane depolarization, production of reactive oxygen species (ROS), nitric oxide (NO) and activation of Mitogen-Activated and Calcium-Dependent Protein Kinases (MAPKs and CDPKs).

13. Conti..... Step 4: TF modulation activities
These signaling events modulate transcription factor (TF) activities
Leading to massive transcriptional reprogramming related to defense.

14. Conti..... Step 5:Activation of defense gene
1. Pathogenesis-related (PR) proteins
Hydrolytic enzymes
β-1,3-glucanases and chitinases………………..degrade microbial cell walls
Defensins…………………disrupting pathogen membrane
Peroxidases, proteinase inhibitors or lipid-transfer proteins

15. Conti.....
2. Compounds with antimicrobial activity such as phytoalexins
3. Lignin and callose deposited to the cell wall assuring its strengthening
4. Production of ROS with a signaling role and direct antimicrobial effect
5. Stomatal closure

16. Conti.....
 Which one is ultimately tunning and orchestring these responses????
Phytohormones such as
Salicylic acid (SA),
Jasmonic acid (JA),
Ethylene (ET)
Abscisic acid (ABA)
Brassinosteroids (BR)
Gibberellins

18. Resistance inducers 1. Chemical inducers
Exogenously applied SA provided a broadspectrum disease resistance in tobacco leaves (White, 1979).
Acibenzolar-S-methyl (ASM), named also benzothiadiazole (BTH) is an efficient broad-spectrum resistance inducer against bacterial, fungal and viral diseases in different monocot and dicot crops (Walters et al., 2013). Its commercialized forms known as Bion or Actigard (Syngenta) are widely used in agriculture.

19. Conti.....
Probenazole, applied to rice crop…… control rice blast, caused by a fungus Magnaporthe grisea and bacterial leaf blight, caused by Xanthomonas oryzae pv. oryzae.

20. 2. Microbial elicitors 2.1. Bacterial elicitors
Three major categories
BDCs , Effector class of BDCs, plant-associated microorganisms (Beneficial bacteria)
BDCs
These are the molecules with conserved sequence (MAMPs)
Released either from bacteria.
Released accidentally from bacteria (DNA, transcription, translation factors).

21. Name Functional class Origin Pathogen Host Selected references
Lipopolysaccharide (LPS)
Cell wall
(outer membrane)
component; MAMP
Gram-negative
bacteria
Avirulent bacteria;
Brassica
campestris;
Arabidopsis
Newman et al. (2002)
Flagellin
Flagellar
Several
Pseudomonas syringae pv.
tomato; etc.
Arabidopsis most higher
plants)
Zipfel et al. (2004)
EF-Tu; elf18/26
Translation factor;
MAMP
(Poly)peptide
Escherichia coli
tomato
(Brassicaceae
only)
Kunze et al. (2004)
2,4-Diacetylphloroglucinol
Toxin (antibiotic);
Pseudomonas
fluorescent
Peronospora parasitica
Iavicoli et al. (2003)

22. 2.2 Effector class of BDCs
can readily reach the plant cytoplasm, via a conduit called type III secretion system (T3SS). The T3SS effectors are aimed to manipulate host metabolism.

23. 2.3 Plant-associated microorganisms (Beneficial bacteria)
Some BDCs appear more feasible for practical plant protection than others, because they are inclusively delivered along with PGPR and/or bacterial endophyte cells.

24. Name
Functional class
Origin
Pathogen
Host
Selected references
Dimethyl disulfide
VOC
Bacillus
(PGPR)
Botrytis cinerea
Tobacco; corn
Huang et al. (2012)
Nod factors
(lipochitooligosaccharide)
Symbiotic signal
Rhizobia
Microsphaera
Soybean
Duzan et al. (2005)

25. 2.2 Fungal elicitors
The treatment with chitin reduced the susceptibility of rice to M. oryzae (Tanabe et al., 2006).
Chitosan was able to induce the level of chitinase activity and new isoforms of chitinase, resulting in the reduction of early blight disease in tomato leaves. (Sathiyabama et al., 2014).
Tomato plants grown in the soil amended with monosilicic acid and chitosan slowed down the development of bacterial wilt (Kiirika et al., 2013).

26. 3. Plant extracts 3.1. Algal extracts
Initial work was demonstrated on Rubus fruticosus L. in (Patier et al., 1995)…….algal polysaccharides ……induce resistance against a broad range of pathogens and this capability relies mostly on the level of their sulfatation.

27. Algal extract
source
Recent applications/research as plant protectors
refrences
Laminarins and sulfated laminarin (PS3)
brown algae such as Laminaria digitata
B. cinerea and Plasmopara
viticola in a grapevine.
(Aziz et al., 2003) and (Gauthier et al.,2014)
Ulvans
Ulva
studies were completed both on resistance induction against pathogens and defense mechanisms.
(Stadnik and de Freitas, 2014)
Carrageenans
red algae
long-lasting protection against biotrophic as well
as hemibiotrophic pathogens
(Mercier et al., 2001; Vera et al., 2012).
fucans
brown algae as Ascophyllum nodosum, Fucus spp. and Ecklonia spp.
data on their elicitation effect on plants are rather scarce.
(Klarzynski et al. 2003)

28. Extracts of higher plants
Traditionally plants have been a valuable source of biologically active compounds especially for medicinal purposes.
Various herbal extracts were also previously used to protect plants from pests and diseases but on a smaller scale. Now they are making a comeback in the form of so-called botanical biopesticides. Their direct antimicrobial effect to plant pathogens has been demonstrated many times.

29. Most commercially successful species with protective activity
Giant knotweed (Reynoutria sacchalinensis (F. Schmidt) Nakai). An ethanolic extract of this plant was registered in 1990s as Milsana® has been proven to protect cucumber from powdery mildew (Daayf et al., 1995)
Widely used other plants include , Azadirachta indica and Hedera helix.
Recently, plant essential oils is considered as an efficient source of resistance against pathogens.
e.g. Essential oil from Gaultheria procumbens

30. 4. Composts
Composts are products of aerobic biodegradation of different types of organic waste, which are mostly used as peat substitutes and soil amendments.
Their suppressive effect against pathogens has been ascribed primarily to microbial populations colonizing rhizosphere and their competitive activity and antibiosis against root pathogens.
However, a number of studies indicate involvement of induced resistance mechanisms.

31. 5.Biochar
Biochar is a coproduct of pyrolized biomass utilized as a soil amendment The results indicate that biochar has a potential to alleviate plant diseases and provide plants to efficient defense resistance against leaf pathogens.

32. Conclusion
Promotion of plant disease resistance by stimulation of crops using bio- based compounds represents an alternative to chemical pesticides.
During the last years, a boom of studies extended our knowledge of the potential of this approach. A high number of resistance-inducing compounds of different origins and nature were reported and their efficiency was evaluated in various plant-pathogen systems.
Bio-based resistance inducers can be combined with biopesticides, biological control agents, biostimulants and even chemical pesticides, which could result in reduced pesticide consumption.

33. Reference:
Burketova, L., L. Trda , P. G. Ott and O. Valentova Bio-based resistance inducers for sustainable plant protection against pathogens. Biotechnology Advances 33 :994–1004.