Strigolactones is plant compund which helps in plant development,protection,nutrient uptake and stress tolerence.

1. Effect of Strigolactones in plant signal transduction and
development
Rakesh sarma
Ph.D Research scholar
Department of Plant Physiology
BHU,Varanasi

2. Introduction

3. Striga spp growing on rice (a) Striga
hermonthica, (b) Striga asiatica
Member of Orbanchaceae
family.
Parasitize cereal crops rice,
sorghum and maize.
Hemiparasites - green
leaves -unable to perform
sufficient photosynthesis for
their survival.
 elevated transpiration rates
enabling them to obtain larger
quantities of water and
nutrients from their host.

4. (a) Orobanche Cumana growing on sunflower, (b) Orobanche
aegyptiaca growing on tomato. Holoparasites that lack chlorophylls.
They parasitize dicotyledonous crops including tomato, tobacco,
carrot, clovers, cucumber, sunflower, and legumes.

5. Life cycle of a root parasitic plant, Orobanche minor. (a) Seed
germination is elicited by host-derived stimulants, including
strigolactones. (b) Seedling attaches to host root with haustoria. (c–
d) Parasite tubercles grow underground for several weeks or months
before emergence of the flowering shoots. (e) The parasite produces
a large number of seeds, which remain viable for many years in soil.

6. History Discovery: 1960 (germination stimulant )
 Name: root parasitic plant striga
Shinjiro Yamaguchi (2008): inhibits shoot branching.
Recently, role in plant development and adaptive
responses.

7. Biosynthesis and
Perception of SLs

9. A model of SL signalling pathway through SL hydrolysis
Germain et al., 2013

11. 5-Deoxystrigol, strigol and orobanchol are natural SLs.
GR24 is a synthetic SL analog.

12. Mutant
RMS (Ramosus of Pea)
DAD(Decreased apical dominance of Petunia)
MAX (More axillary growth of Arabidopsis)
D (Dwarf) or HTD (high tillering dwarf) of Rice

13. Pea wild-type plant (left) and rms1 high
branching mutant plant (right)
Arabidopsis strigolactone-deficient
mutant max3 of shows exuberant
branching

14. b | A schematic representation of grafting experiments carried out with Arabidopsis
thaliana mutants that are impaired in the strigolactone pathway. These mutants were
identified on the basis of their increased branching phenotype. The increase in branching
observed in the strigolactone biosynthesis mutants (more axillary growth 1 (max1),
max3 or max4) can be restored to the wild-type levels by grafting the mutant shoots onto
wild-type roots, demonstrating that the inhibitor can move from the roots to the shoots.
Domagalska and Leyser (2011)

15. Spira et al., 2012

16. Role of SLs in Plant
Development

18. Seed Germination
Natural and synthetic SLs have moderate to
potent germination activity.
Hydroxy-SLs are 10-fold to 100-fold more active
than their acetates and other conjugates.
Germination stimulation activity of SLs on one
parasitic plant species may be different from that
on the other species. For example, under
laboratory conditions, sorgomol, originally
isolated from sorghum root exudates, is more
active on Striga spp. than on Orobanche spp.

19. Secondary Growth
Agusti et al. (2011): Pea and Eucalyptus plants

20. Leaf SenescenceDelayed
leaf
senescence
mutant

21. Cheng et al., 2013
Abbreviations: P, primordium; DM, distal meristem; PM, proximal meristem;
AM, apical meristem; BM, basal meristem; TZ, transition zone; EZ,
elongation zone; DZ, differentiation zone; FC, founder cell .

23. Role of
Strigolactones in
Nutrient-Stress

24. Marzec et al., 2013

26. Czarnecki et al., 2013

27. Effect of SL treatment on survival of SL-deficient and SL-response mutants and WT plants. (A)
Three-wk-old WT and SL-deficient max3-11 and max4-7 and SL-signaling max2-3 mutant plants before
drought stress. (B) Three-wk-old plants subjected to a drought stress ( 5 mL of 5 μM SL or water, the first
day and from the 7th to the 13th days and twice in a day at 10:00 AM and 4:00 PM). Plants were
photographed 3 d subsequent to rewatering and after removal of inflorescences from the surviving plants.
(C) Nonstressed WT and max plants sprayed with 5 mL of 5 μM SL or water as shown in B. (D) Percent
survival of mutant and WT plants sprayed with SL or water and subjected to a drought stress.
Ha et al., 2013.

28. Conclusion
Strigolactones are signaling compounds made by plants. They have
two main functions:
1. Endogenous hormones to control plant development.
2. Components of root exudates to promote symbiotic interactions
between plants and soil microbes.
 Some plants that are parasitic on other plants have established a
third function, which is to stimulate germination of their seeds when
in close proximity to the roots of a suitable host plant.
 SL acts as positive regulator of plant responses to drought and salt
stress, which was associated with shoot- rather than root-related
traits.
Genetic variation in strigolactone responses could provide an
opportunity to breed plants with superior nutrient use efficiency and
ability to form symbiotic associations.

29. We have a long history of research inWe have a long history of research in
plant hormones, we are still ignorantplant hormones, we are still ignorant
about many things. I think there are otherabout many things. I think there are other
plant hormones that still remainplant hormones that still remain
undiscovered, and I really hope to findundiscovered, and I really hope to find
them.”them.”
Shinjiro YamaguchiShinjiro Yamaguchi
Future
perspective

30. THANK YOU for
attention