Due to varying climate change abiotic stresses play a major role in imparting crop loss. The understanding the mechanisms of complex abiotic stresses is a main constrain in the crop breeding. Wind is such a complex stress causing variable number of stresses including both mechanical and air flow. It can also cause direct and indirect effects causing severe crop losses.

2. Wind : Effects
WIND
DIRECT
EFFECTS
AIR FLOW
MECHANICAL
(THIGMOTROPISM)
INDIRECT
EFFECTS
SOIL EROSION
& ABRASION
DISEASE
SPREAD

3. INDIRECT EFFECT

4. DIRECT EFFECT

5. DIRECT EFFECT

6. DIRECT EFFECTS
• Wind: affect development and alter
morphology
• Wind exposed plants: fewer, smaller leaves
which contain a higher proportion of
mechanical tissues
• Wind : Complex phenomenon

7. DIRECT EFFECTS
• Stress due to wind flow and mechanical stress :
both have different effects
– responses of plants to wind :
• depend on the relative importance of air flow and
mechanical stress effects
• depend on the overall environmental conditions as well as
the characteristics of the plants themselves.
– factors include
• humidity
• the magnitude, frequency and duration of wind loading
• leaf shape and size and the overall shape
• drag coefficient of the vegetation stand in which a plant is
growing

8. • Induce stress in
– Leaves
– Stem
– Roots
– Other parts
• The decrease yield due to wind exposure
– 30% for sorghum
– 24% for barley
– 48% in the marigold
DIRECT EFFECTS

9. Wind stress in leaves
• leaves are probably most strongly influenced
• A gentle breeze - increase the photosynthesis -
low winds reduce the thickness of LEAF
boundary layer – decrease resistance to
movement of carbondioxide into the leaf

10. Wind stress in leaves
• strong winds
– reduce photosynthesis
• lowering leaf temperatures below the optimum,
reducing stomatal conductance to prevent excessive
water loss
• by causing leaves to roll up or curl inwards, which
reduces their effective leaf area (Telewski, 1995).
• The precise effect :depends on the morphology of the
leaves, the optimal temperature of the photosynthetic
enzymes, and the wind speed as well as other
environmental factors

11. Wind stress in leaves
• Higher transpiration reduces leaf temperature
and may dehydrate plants
• Leaves with large surface area to volume ratios -
maximizes the light capture per mass invested
– prone to mechanical failure under bending and
tearing by wind forces (Wilson, 1984)

12. Wind stress in leaves
• Reduced biomass in leaf lamina and petioles -
reduced leaf size and flexural stiffness of petioles-
reduced mechanical loads and increased leaf
flexibility (Read & Stokes, 2006).
• Leaves of wind-exposed plants had thicker laminas
and tended to have higher water content
• Wind-exposed plants also had shorter petioles and
rounder (relatively shorter and wider) leaf blades
• wind-induced phenotypic changes in at least some
leaf traits were associated with preventing
dehydration

13. Stress in stem
• Inhibition of stem elongation, and increases in
stem diameter and root allocation (Jaffe &
Forbes, 1993; Telewski & Pruyn, 1998)
• These responses, denoted as
thigmomorphogenesis - increase a plant’s
resistance to mechanical stress

14. Stress in stem
• Can induce responses that are different those
induced by pure mechanical stress: production
of thinner more elongated stems under wind
loading (Henry & Thomas, 2002; Smith&Ennos, 2003).
• A reduction in flexural stiffness-increases
flexibility-ability to reconfigure under wind
loading
• STEM TENDRILS

15. Stress in stem
• Trees : increases in the amount of secondary wood - producing thicker
trunks and roots
• "flexure wood" to describe the extra wood formation found in tree stems
as a result of bending
• “reaction wood” - forms when the stem is permanently displaced
• Flexure wood is more dense than normal wood- with a smaller tracheid
lumen size and microfibrils in the cell wall
• Flexure wood is more rigid with a greater inertia and flexural stiffness than
normal wood-maintain the stem in a vertical position during windy
conditions

16. Effect on roots
• changes in root development-enhance
anchorage strength
• Root architecture and uprooting strength
• Secondary thickening of stem is continuous with
that in the top lateral roots
• Increase in stem radial growth may be reflected
in root growth.
• influence the resistance to bending of the roots
and hence improve anchorage strength.

17. Effect on roots
• increase in the numbers of large roots
• more branched than the roots growing
perpendicular to the wind direction
• The higher the concentration of roots per unit
area of soil, the greater the tensile strength
• when branching becomes more random on the
windward side only, resistance to overturning
increases.

18. Signals and wind responses
• Hormones
• secondary messengers
• nitric oxide (NO)
• reactive oxygen species (ROS)
• lipid-derived metabolites
Potential
signaling
factors.

19. Calcium
• Calcium (Ca2+) is a universal signal
transduction molecule
• Plants can’t tolerate Ca2+ levels outside the
cells (10-3 M)
• Cytosolic Ca2+ at low concentrations by active
removal to extracellular spaces or to
intracellular organelles

20. Wind/ Perturbation
Cytosolic
Ca2+
increases
TCH genes activated
Ca2+ sensors :
Calmodulin (CaM) &
Calmodulin like proteins
(CAL)
Activation
Modulate target enzymes
Physiological response

21. JASMONATES
• Jasmonates (JAs) are a family of
cyclopentanone derivatives synthesized from
linolenic acid via the octadecanoid pathway.
• Lipid-derived metabolites, which include
jasmonic acid (JA), its methyl ester (MeJA),
and 12-oxo-10,15-phytodienoic acid (12-
OPDA)

22. JASMONATES
• Implicated in plant thigmomorphogenetic
responses to mechano-stimulations
• Intracellular MeJA levels in coiling tendrils are
more elevated compared with those from
already coiled ones

23. perturbation
Increase Ca2+
levels
Localisation of PLD
to membranes
Active PLD
Free polyunsaturated
FA
jasmonates
Thigmomorphogenic response
Increase (LOX)
transcripts
PLD= phospholipase D
LOX= lipoxygenase

24. ETHYLENE
ACS = 1-aminocyclopropane-1-
carboxylate synthase
Stimuli
Up regulation of ACS
Enhanced Ethylene
production
Interact with other
growth hormones
Thigmomorphogenic
responses

25. ABA
• Abscisic acid (ABA) –regulates stress responses
and developmental processes
• The in vivo accumulation of ABA retards
and/or suppresses plant growth
• GROWTH RETARDATION
• MECHANISM NOT CLEARLY KNOWN

26. AUXIN
• Mechanical stimulation of soybean and pea
plants reverses auxin-promoted shoot
elongation
• A major mechanism for auxin turnover is
peroxidase-mediated oxidative
decarboxylation
• An increase in the peroxidase activity occurs
in mechanically perturbed plants

27. (PID) = pinoid =serine/threonine protein kinase
Stimuli
Ca 2+ sensor TCH3
Regulation of PID
Regulate auxin
regulators (PIN family)
Auxin signalling and
thigmomorphogenesis

28. Nitric oxide
• Nitric oxide (NO) is involved in regulating
various developmental and physiological
processes in plants, including seed
germination, cell differentiation, transition to
flowering, and Senescence
• the function of CML24 is required for
appropriate NO production and accumulation
• CML24 in transducing Ca2+ signals important
for regulating NO accumulation.

29. Reactive oxygen species
• Plants subjected to various environmental
stresses, including mechanical stress,
accumulate hydrogen peroxide (H2O2) and
superoxide O2 , reactive oxygen species (ROS)
• Cells may utilize ROS as signalling molecules to
regulate the expression of genes

30. •Reduction of plant height :large increases in yield :due to lodging
resistance, improved harvest index, and more efficient utilization of
the environment
•involvement of the dwarfing genes with the gibberellin
biosynthesis,
•Dwarf mutants : GA biosynthetic and signal transduction pathway
•1917, the dwarf wheat genotype ’Daruma’ was crossed to ‘Fultz,’ a
land
race imported from the United States to Japan
•1925, Japanese breeders crossed ‘Daruma’—‘Fultz’ with ‘Turkey,’ a
Russian wheat land race
•Selection of ‘Norin10- released in Japan in 1935- stiff, short
stemmed wheat varieties

31. • S. C. Salmon introduced 16 varieties of this plant type
to the United States: available to breeders in 1947–
1948.
• The crosses between ‘Norin10’ and the American
varieties : first variety ‘Gaines’ was released in 1962
(Morrison and Voguel, 1962)
• Voguel sent lines of this cross in 1953 to Norman
Borlaug- CIMMYT in Mexico
• Borlaug used them intensively to develop new types of
wheat :responsible for the “Green Revolution
• Dwarf mutants defective for different steps in the GA
pathway

32. GA sensitive
Crop Dwarfing genes
maize, an, d1, d2, d3, and d5
wheat, Rht4, Rht6, Rht7, Rht8,
Rht9, Rht11, and Rht17 are recessive
genes; Rht12 is a strong dominant gene
the rye Ddw1, Ddw2 (dominant genes), and d2
(recessive
gene)
oat Dw6, Dw7, and Dw8
GA insensitive
Crop Dwarfing genes
wheat Rht1 and Rht2 genes(norin 10)
rice sd1 from ‘Dee-geo-woo-gen’
maize d8 and d9 genes in
Wheat Rht-B1b, Rht-D1b, Rht-B1c, and Rht-D1c