The document discusses insights into the phyllosphere, the surface of aerial plant parts, and its microbial community dynamics, highlighting types of microbes and their survival strategies against environmental stresses. It outlines the history of phyllosphere research, the ecological factors influencing microbial diversity, and the functional roles of phyllospheric microflora, such as promoting plant growth and remediating pollutants. Additionally, it emphasizes the importance of understanding these microorganisms for biotechnological applications in agriculture and environmental health.

2. Doctoral seminar on
“New insights into the structure
and functional dynamics of
phyllosphere microflora”
By
YALAVARTHI NAGARAJU, Ph.D (Ag)

6. Classification
Phyllospher
e
Caulospher
e
Anthosph
ere
Carpospher
e
Phylloplane

7. Which part of the plant doesn’t contain
microbes ?

8. Kinds of stresses
1. Seasonal cycle
2. Developmental,
morphological changes
in plant
3. Day and night cycle
4. Limitations of nutrients
5. Physiochemical
constraints (light,
temperature, radiation,
desiccation)

9. How they survive on the leaves?
Tolerance strategy which permits the
inhabitants to tolerate direct exposure
to environmental stresses on the
surface of the leaf mainly UV
radiation and low moisture
conditions
Eg: Saprophytes typically employ
tolerance strategies to survive in the
foliar zone, as they cannot survive
endophytically
Avoidance strategy which allows the
epiphytes to colonize sites that do not
face these stresses (Beattie and
Lindow, 1995)
Eg: Foliar pathogens can utilize both
the strategies to harbour the plants
more efficiently
Avoidance
Nutrient
limitation

10. Hotspots on leafs
 Bases of trichomes,
 Stomata,
 Epidermal cell wall junctions and
 Grooves along veins
(Beattie & Lindow, 1999)

11. Introduction
 Phyllosphere is the surface and interior of the aerial parts
of vascular plants (Newton et al., 2010)
 Most of the phyllosphere colonizing microorganisms live
as commensals on their host plants
 About 0.1–8.4 % of the total bacterial population were
cultivable (Rastogi et al., 2010)
 The phyllosphere has an area of roughly about one billion
square kilometres (Morris and Kinkel, 2002), in which the
number of bacteria may reach up to 106–107 cells per
square centimetre of leaf area, which is roughly 1026 ells

12. History
1955- The term phyllosphere was first introduced by the
plant pathologist F.T. Last
1956 - “Phyllosphere” term was coined by Ruinen
1987 - Kinkel tested the equilibrium theory of island
biogeography, assuming that individual leaves form discrete
habitat patches for microbes analogous to oceanic islands for
macroorganisms.
2002 – Morris extended the concept to include both the areas
inside and outside the leaf
2012- Berlec considered phyllospheric microflora as “Plant
probiotics”
2015- Doan and Leveau divided the phyllosphere into two
unique niches i.e., Phylloplane (the leaf surface landscape)
and phyllotelma (the leaf surface waterscape)

13. How they will solve the problem of
carbon, energy?

15. Research article

16. Picea abies
Cinara spp

17. No.of trees
No.of twigs/tree
Natural predators attack
Overwintering eggs
Low egg densities

18. L1-L4 Larval instars

19. May (Spring)
July (mid summer)
September
1. Complete medium
2. Mineral medium with NH4
+
3. Mineral medium with NO3
-

20. Structure of phyllosphere microflora

21. Community structure

22. Ecology of phyllosphere microbiota
 Actinobacteria
 Bacteroidetes
 Firmicutes
 Proteobacteria
(Bulgarelli et al., 2013)
 Pseudomonas
 Sphingomonas
 Methylobacterium
 Bacillus
 Massilia
 Arthrobacter
 Pantoea
Species richness in fungi is one order of magnitude lower than
that of bacteria (Finkel et al., 2011).

23. Core phyllosphere community of crops
Rice
Rhizobium,
Methylobacterium, and
Microbacterium,
Lettuce
Pseudomonas,
Bacillus,
Massilia,
Arthrobacter, and
Pantoea
Soybean, clover,
Arabidopsis
Sphingomonas,
Methylobacterium

24. Phyllosphere microbial community in green
house conditions

26. Major drivers of phyllosphere microbiota
composition
1) Geographical location
Eg: 1 salt excreting desert tree Tamarix
In this plant major determinant of phyllosphere
microbial community structure is geographical
location. It is evidenced by the fact that
different species of Tamarix (T. aphylla, T.
nilotica, T. teragina) grown in same
geographical location supported similar
bacterial community whereas, plants grown in
different locations showed strong correlation
with geographical differences (Finkel et al.,
2012)
Eg: 2 similar results were found in lettuce
crop, increased distance between lettuce
production sites resulted in more diverse
community structure (Rastogi et al., 2012)

27.  Unlike plants and
animals, bacteria did
not exhibit an
elevational gradient
in their diversity
(Fierer et al., 2011)

28. 2) Climatic factors

30. Research article

35. 3) Plant genetics
 Phyllosphere communities associated with
Pinua ponderosa were fairly similar to each
other irrespective of the geographical
location (Whipps et al., 2008)
 A microbial survey of different cultivars of
lettuce grown in the same field showed that
they supported different bacterial
communities on their foliage (Hunter et al.,
2010)
 It was suggested that these differences
correlated with plant genetic components
that regulate leaf texture and the leaching of
metabolites to the leaf surface

36. Is it possible to manipulate community
structure?
Yes, we are already doing it…..

37. Microbial
manipulation
on foliage
Application of
antibiotics
Crop
management
practices
Nitrogen
fertilization
Application of
pesticides

38. Research article

42. functions of phyllospheric
microflora

44.  Production of growth promoting hormones
 Production of pigments
 Production of volatile organic compounds
 Extracellular oligosaccharides
 Cross kingdom signals
 Quorum sensing
 Cycling of elements as saprophytes (Global N and C cycles)
 Remediating residual pesticides and atmospheric
hydrocarbon pollutants
 Help in plant development and health as biofertilizers,
phytostimulators and biopesticides to protect against
invading pathogens (Lugtenberg et al., 2002; Delmotte et al.,
2009; Zhou et al., 2011; Ali et al., 2012)
Functions

45. Growth hormones
 Auxins Eg: IAA
produced by
Sphingomonas
 Cytokinins
 Brassinosteroids,
 Gibberellins,
 Abscisic acid,
 Ethylene,
 Jasmonates and
 Strigolactones

48. Pigments
Sphinomonas
Pantoea
Clavibacter
Sphingomonas – astaxanthins
Methylobacterium - carotenoids (Xanthophylls)
Clavibacterium – Xanthophylls
Pantoea –carotenoid
Xanthomonas –Xanthomonadin

50. UV Protection mechanisms
1. Methylobacterium, Sphingomonas, Pseudomonas etc.,
possess pigmentation
2. Special DNA repair mechanisms
3. Up regulation of stress response proteins (Eg: PhaA)
4. Production of extracellular polysaccharides

51. Pollinator
Attractions
Floral
volatiles
(terpenes)
Movement
of plants

52. VOC’s
 “Volatile organic compounds (VOCs) are a large class of
low-molecular-weight, carbon-containing compounds
characterized by their high volatility, low vapor pressure
(≥0.01 kPa at 20 °C), and low water solubility” (Herrmann,
2010)
 To date, a total of 1700 volatile compounds have been
isolated from more than 90 plant families.
 Plant volatiles constitute about 1 % of plant secondary
metabolites and are mainly represented by terpenoids,
phenylpropanoids/benzenoids, fatty acid derivatives, and
amino acid derivatives.
 Volatile organic compounds (VOC) are organic
chemicals that when released into the atmosphere can react
with sunlight and nitrogen oxides (NOx) to form tropospheric
(ground-level) ozone (Melanie et al., 2010)

53. TMTT=trimethyltrideca‐1,3,7,11‐tetraene
DMNT= homoterpenes, (E)‐4,8‐dimethyl‐1,3,7‐nonatriene

55. Bacterial
VOCs
alkenes
alcohols
ketones
Terpenes
Fungal
VOCs
alcohols
Benzenoids
Aldehydes
Ketones

56. Why we need to study about phyllosphere?
 Improving our understanding about the behaviour of
microorganisms in this habitat will facilitate biotechnological
applications for protecting plants,
 Promoting plant growth,
 Avoid human pathogenic bacteria in plant food and,
 Phytoremediation of volatile pollutants from the air.

57. Research article

58. Tillandsia spp

63. Research article