A short presentation on types of toxins, mycotoxins and their effects

1. Toxic metabolites affecting seed quality and its impact
on human, animal and plant health
Presented by- KAPIL JINDAL
Presented by: Kapil Jindal
Id no. 21412MPP005

2. Toxins are low molecular weight compounds (metabolites) produced by
microorganisms that are toxic to plant and animals
TOXINS
Toxins can be small molecules, peptides or proteins that are capable of
causing disease on contact with or absorption by body tissues interacting
with biological molecules like enzymes or cellular receptors

3. Classification of toxins
role in pathogenesis
Pathotoxins
Phytotoxins
Vivotoxins
specificity to host
Host specific toxins
Non-specific toxins

4. On the basis of their role in pathogenesis
• The toxin produced in vivo (in the infected tissues)
• functions in disease development, but not as the initial inciting
agent.
Ex. Fusaric acid, pyricularin
Pathotoxins
Phytotoxins
• phyto-toxic substances produced by pathogenic microorganisms.
• primary determinants of disease and the pathogenicity.
• induces all the typical symptoms in reasonable concentrations.
• Host specific toxins.
Ex. H.V. toxin, T. toxin, A.M. toxin
• Toxins produced by pathogens
• toxic to host and non-host plants.
• Non-specific toxins are considered as phytotoxins.
• required for virulence and are important for (disease
inducing).
Ex. Tab-toxin, Ten-toxin, Phaseolotoxin.
Vivotoxins

5. On the basis of specificity to host
Specificity of host
Host specific
Non host specific
Toxins which are toxic to only specific host plant or
species or varieties
Ex. H.V. toxin, T. toxin, A.M. toxin
Toxins which are toxic to both host and non-host.
Ex. Tab-toxin, Ten-toxin, Phaseolotoxin.

6. Host specific:
SN HOST SPECIFIC TOXIN PRODUCER ORGANISM HOST/DISEASE
1 Victorin or HV toxin Cochliobolus victoriae Victoria blight of oats
2 HC Toxin race 1 C.Carbonum Leaf spot of corn
3 T toxin C.Heterosporus Southern corn leaf blight
4 HS toxin C.Sacchari Eye spot disease of
sugarcane
5 AK toxin Alternaria alternata Japanese pear
6 AF-toxin Alternaria alternata Strawberry
7 ACT toxin Alternaria alternata Tangerine
8 AM toxin Alternaria alternata Apple
9 AAL toxin Alternaria alternata Tomato seedling
10 ACR toxin Alternaria alternata Rough lemon
11 ACL toxin A. Citri Lemon
12 Destruxin A. Brassicae Brassicas
13 homodestruxin A. Brassicae Brassicas
14 PC toxin Periconia circinata Grain sorghum

7. Non host specific
SN. TOXIN PRODUCER HOST/DISEASE
1 Tabtoxin Pseudomonas syringae pv. tabaci Wildfire disease
2 Phaseolotoxin Pseudomonas syringae pv. Phaseolicola Bean blight
3 Coronatine Pseudomonas syringae pv. Atroseptica -
4 Syringomycine Pseudomonas syringae pv. syringae -
5 Syringotoxin Pseudomonas syringae pv. syringae -
6 Tagetoxin Pseudomonas syringae pv. syringae -
7 Tentoxin Alternaria alternata Seedling chlorosis
8 Cercosporin Cercospora sp. -
9 Fumaric acid Rhizopus sp. -
10 Oxalic acid Sclerotium sp. Chestnut blight
11 Alternaric acid Alternaria sp.
12 Ceratoulmin Ceratocystis ulmi Dutch elm disease
13 Fusaric acid Fusarium oxysporum Cotton wilt
14 Lycomarasmin Fusarium oxysporum -
15 piricularin Pyricularia oryzae Paddy blast

8. A) Changes in cell permeability: Toxins kill plant cells by altering the
permeability of plasma membrane, thus permitting loss of water and electrolytes and
also unrestricted entry of substances including toxins. Cellular transport system,
especially, H+ / K+ exchange at the cell membrane is affected.
B) Disruption of normal metabolic processes
 Increase in respiration due to disturbed salt balance
 Malfunctioning of enzyme system Ex: Piricularin inhibits polyphenol oxidase.
 Uncoupling of oxidative phosphorylation
C) Interfere with the growth regulatory system of host plant
Ex: Restricted development of roots induced by Fusarium moniliform
Effect of toxins on host tissue

9. Toxin-producers:
• Some bacteria:
e.g., Pseudomonas, Burkholderia, Clavibacter, Streptomyces,
Xanthomonas
• A number of fungi:
e.g. Alternaria, Ascochyta, Bipolaris, Botrytis, Cercospora,
Cochliobolus, Colletotrichum, Drechslera, Fusarium, Phoma

10. Mycotoxins
• Mykes = Fungus / Mold Toxicum= Poison
Mycotoxins are chemicals and secondary metabolites
produced by Fungi/ Moulds growing on crops in field and
storage under appropriate environmental condition that are
harmful to humans and domestic animals.
Diseases caused due to mycotoxins are refereed as mycotoxicoses
• More than 300 mycotoxins have been described belonging to
several chemical groups and their structural formulae have been
confirmed.
• Cereals and oilseed are especially prone to mycotoxin
contamination.

11. Mycotoxins have a significant impact on seed quality, leading to
reduced germination, seedling vigor, and overall crop productivity.
mycotoxins that commonly affect seed quality:
Aflatoxins:
• The Aflatoxins Aflatoxins are group of
mycotoxins produced by Aspergillus, mainly
A. parasiticus and A.flavus.
• They are common fungal contaminants of
nuts but are also found in many other
feedstuffs.
• e.g. corn, tree nuts, rice and wheat.
• Aflatoxins B1, B2, G1 and G2 are four
naturally occurring forms of Aflatoxins, B1
being the most potent prevalent.
• • Chemical structure of Aflatoxins.

12. Ochratoxin:
• Ochratoxins, are produced by a number of fungi in
the genera Aspergillus and Penicillium. The largest
amounts ochratoxins are made by A. ochraceus and
P. cyclopium.
• A. ochraceus and P. viridicatum (reclassified as P.
verrucosum), two species that were first reported as
ochratoxin A (OA) producers, occur most
frequently in nature.
• Other fungi, such as Petromyces alliceus, and A.
citricus, have also been found to produce OA. Most
of the OA producers are storage fungi and
preharvest fungal infection.

13. Citrinin:
• It is a toxin that was first isolated from Penicillium citrinum.
• It is identified in several species of pencillium and aspergillus.
• Some of these species are used to produce human food stuffs such as cheese
(Penicillium camemberti), sake, miso, and soy sauce (Aspergillus oryzae).
• Although it is associated with many seeds (wheat, rice, corn, barley, oats, rye)
• Citrinin can also act synergistically with Ochratoxin A to depress RNA synthesis.

14. Ergot Alkaloids
• They are compounds produced by the Sclerotia species of Claviceps.
• The ingestion of ergot sclerotia from infected cereals, commonly in the form of bread
produced from contaminated flour, cause ergotism the human disease historically known
as Anthony's Fire.
• There are two forms of ergotism: gangrenous, affecting blood supply to extremities, and
convulsive, affecting the central nervous system.

15. Patulin:
• It is a toxin produced by the P.expansum, Aspergillus, penicillium, fungal species.
• P. expansum is especially associated with a range of moldy fruits and vegetables, in
particular rotting apples and figs.
• Although patulin has not been shown to be carcinogenic, it has been reported to
damage the immune system in animals.
• In 2004, the European Community set limits to the concentrations of patulin in food
products.

16. Fumonisins:
• Produced primarily by Fusarium fungi.
• fumonisins are commonly found in maize and maize-derived products.
• These toxins can cause various health issues in animals and humans.
• They can also negatively impact seed quality by reducing germination and
causing abnormalities in seedlings.
Trichothecenes:
• This group of mycotoxins is produced by various Fusarium species.
• They can contaminate grains and cereals, affecting seed quality by inhibiting
germination, causing seedling diseases, and reducing overall plant health.

17. Zearalenone:
• Another mycotoxin produced by Fusarium fungi.
• zearalenone primarily affects maize, barley, and wheat.
• It has estrogenic effects and can lead to reduced seed quality, including decreased
germination rates.
Deoxynivalenol (DON):
• Also known as vomitoxin.
• DON is a common trichothecene produced
by Fusarium species.
• It often affects wheat, barley, and maize.
• High levels of DON can lead to reduced
seed germination and seedling vigor.

18. I. Effect on human health :
• degeneration and malfunctioning of kidney
• disorders of respiratory system especially in lungs and bronchitis.
• adverse effect of liver functioning & related metabolism, toxic hepatitis.
• cardiac problems.
• esophageal abnormalities, fever, reduced mental alertness & cervical problems.
II. Effect on animal health :
• Consumption of mycotoxin contaminated feed results in low productivity.
• determined quality of milk, egg and meat of animals.
• The medicines are ineffective in mycotoxicoses and animals are prone to
outbreak of other diseases.
• Ex. Turkey X disease caused by Aflatoxin
Significance of mycotoxins

19. III. Seed and seedling diseases:
• inhibits the seed germination and emergence.
• Abnormal elongation in lettuce hypocotyls.
• reduced chlorophyll and nucleic acid synthesis in maize.
• Heavily infected seeds of soybean, groundnut and maize with
Aspergillus flavus exhibit total seed rot.
IV. Phytosanitary regulations:
• With the emergence of WTO, the trade of mycotoxin free
seeds, planting material, processed food and feed has assumed
a greater significance.
• For the production and marketing of an end product extreme
care is an obligatory measure and no-toxin certificate are
mandatory.
• The import-export of the commodity is adversely affected due
to fungal infection

20. Mycotoxicoses Causal organism Toxins produced Affected ones
Ergotism Sclerotia of Claviceps spp. Ergotin Man , cattle, sheep, horse,
poultry pigs
Afla-toxicoses Aspergillus flavus
A. parasiticus
Afla-toxin B1, B2, G1 & G2 Man
Turkey X disease in poultry
birds
Nephro-toxicoses Aspergillus ochraceus ,Penicillium
viridicatum,P. citrinum, P. expansum
Ochratoxin
Citrinin
Animals (pigs)
Fusariotoxicoses Fusarium sporotrichioids Fusariogenin Man (Septic angina)
& animals (horse,cattle, pigs)
Pink rot
dermatitis
Sclerotinia sclerotiorum Psoralens Man
Lupinosis Phomopsis leptostromiformis Hepatotoxin Sheep, cattle, Horse
Red Tide
(Algae)
Glenodium spp., Gymnodinium spp,
Gonyaulox spp
Neuro-toxin Human
Important diseases caused by mycotoxins

21. 1. Host factor : Host resistance / susceptibility to the fungi
influence the mycotoxin production.
• Increased toxin production : Higher sugar content and
greater seed surface lipid level of the host enhanced the toxin
production. Ex. Maize affected with Aspergillus spp.
• Decreased toxin production : Lesser size of the hilum
decreased the toxin production. Ex. Resistant varieties of pea nut.
Compactness of sclerotized cells, higher level of lignin and tightness
of cells results in decreased chances of the entry of the fungal
mycelium. Hence, less toxin production.
Factors affecting mycotoxin production

22. • 2. Pathogen factors
i. Levels of Virulence :
ii. Inoculum density : Quantity of Inoculum
iii. Reproduction pattern of the Pathogen
• High birth rate
• Low death rate
iv. Ecology of the Pathogen
• Internally seed borne
• Externally seed borne
• Contaminant
v. Easy & rapid dispersal/Spread of the Pathogen
vi. Adaptability of the pathogen : Pathogen have the
capacity to
adopt in adverse conditions.

23. 3. Agronomic practices & Environmental factors:
• Planting time : Late planted maize had a greater chance for pre-harvest Afla-toxin
production as compared to early planted ones. Late harvesting of peanut results in
an increase in Afla-toxin production
• Soil type : Mycotoxin production is less in vertisols as compared to the crop
grown in alfisols
• Fertilizer levels : Plant stress associated with reduced fertilization increases the
incidence of Afla-toxin. Ex. In maize
• Drought conditions : Drought conditions reduced the yield and predispose the
plants to fungal infection and increases the toxin production
• Damaged pods & kernals : Cracked or wounded pod wall or seed surface
provide the more chances of the fungal entry lead to higher toxin production.
• Insect damage : Insect damage leads to formation of wounds and provide easy
entry to fungal mycelium.

24. • Competition of mycoflora: Aspergillus niger prevents the
infection of A. flavus in peanut.
Metabolites of Neurospora sp. & Rhizopus sp. inhibit the
growth of Aspergillus flavus in pea nut.
• Moisture content: Seed/grain moisture content (>12%)
increases the chance of infection. Low soil moisture favours
the fungal invasion & increase the toxin production
• Temperature : Warm weather favours the fungal growth &
toxin production. Ex. Aspergillus flavus infection on maize
seeds is favoured by high temp. (32-380C) rather than cool
temp. (21-260C)
• Oxygen-CO2 concentration : With increasing CO2
concentration, decrease in toxin production. Similarly
reduced O2 concentration, decrease the toxin production.

25. Conclusion:
The impact of mycotoxins on seed quality and human and animal health
underscores the need for proactive measures to safeguard our
agricultural systems and the well-being of populations.
By integrating scientific innovation, regulatory enforcement, and public
awareness, we can mitigate the adverse effects of mycotoxins and strive
towards a safer and more secure food and feed supply chain.

26. References:
• Modern plant pathology by HC Dube
• Gn agrios plant pathology
• World Health Organization (WHO). (2018). Mycotoxins. Retrieved
from https://www.who.int/news-room/fact-sheets/detail/mycotoxins
• Food and Agriculture Organization (FAO). (2020). Mycotoxin
research and mycotoxin risk assessment. Retrieved from
http://www.fao.org/mycotoxin/index_en.html