Guayule is a desert shrub native to parts of Texas and Mexico that can be used as an alternative source of natural rubber. It produces rubber within its parenchyma cells and has several advantages over the traditional source of natural rubber, the rubber tree. These include hardiness in extreme environments, genetic diversity, and domestic cultivation. While guayule shows promise, it also has challenges such as low seed germination rates, a long juvenile period, and physiological processes related to rubber biosynthesis that are not fully understood. Ongoing research and commercialization efforts aim to further develop guayule as a sustainable source of natural rubber.

1. GUAYULE:
SMALL SHRUB, BIG DREAMS
Bridgestone Internship
Summer 2017
PLS 492
Dr. Tanya Quist
Kelly McDowell

2. GUAYULE INTRODUCTION
• Parthenium argentatum
• Hardy desert perennial
• Native to parts of Texas and Mexico
• Rubber content lies within parenchyma
cells- 2/3 in the stem and branches, and
1/3 in the roots
• Close relative to ragweed and sunflower
Photo: Clarence A. Rechenthin, hosted by the USDA-NRCS PLANTS
Database
Source: Coffelt T, Ray DT, Dierig DA. 100 Years of Breeding Guayule.
Industrial Crops. 2015; 351-367

3. EARLY HISTORY
• First documented use of guayule by Spanish in 1500’s
• Natives observed chewing large wads to make balls for games
Photo: “The Ball Game”, Museo
Amparo,
http://cookjmex.blogspot.com.au/2011
/10/puebla-part-5-gods-men-and-
animals-as.html
Source: Coffelt T, Ray DT, Dierig DA. 100 Years of Breeding Guayule. Industrial Crops. 2015; 351-
367

4. HEVEA BRASILIENSIS- PROBLEMATIC
• Almost entire world production of rubber
and latex originate from sap of Hevea
(Para) rubber tree
• Over forested
• Prolonged breeding cycle and juvenile
periods
• Genetically homogenous, therefore highly
susceptible to devastating disease and
pestilence. Millions of hectares of rubber
plantations are from a small sample of
seeds collected in 1876 by Dr. Henry
Wickam in Brazil
• Native to regions of sociopolitical
instability- presents problem of reliability
for production and export
• South American Leaf Blight, the deadliest
disease for rubber trees, could wipe out
current production of natural rubber and
cause industry collapse with little or no
advance warning.
Photo: Hevea Brasiliensis Plantation, http://www.horizon-custom-
homes.com/HeveaBrasiliensis.html
Photo: Tapping a Rubber Tree (Hevea brasiliensis),
Indonesia.Thomas Marent/Visuals Unlimited, Inc.
http://visualsunlimited.photoshelter.com/image/I0000iTKS.C
he.6w
Sources: van Beilen JB, Poirier Y. Guayule and Russian Dandelion as
Alternative Sources of Natural Rubber. 2007; Critical Reviews in
Biotechnology. 2007; 27:217-321
Cornish, K, Blakeslee, J. Rubber biosynthesis in plants. 2011;
Plant Lipid Biochemistry, American Oil Chemists Society.
http://lipidlibrary.aocs.org/Biochemistry/content.cfm?ItemNumber=
40312

5. RUBBER RUNDOWN
• Annual worldwide natural rubber production is
almost 8.8 million tons
• 10% of latex harvested from Hevea trees is
manufactured into latex products
• Natural rubber is the end product of
isoprenoid/terpenoid synthesis pathway
• cis-1,4-polyisoprene polymer composed from
isopentyl pyrophosphate monomers
• Molecular weight is the prime determining
factor of rubber quality- higher weight
correlates to higher quality
Sources: Cornish, K, Blakeslee, J. Rubber biosynthesis in plants. 2011;
Plant Lipid Biochemistry, American Oil Chemists Society.
http://lipidlibrary.aocs.org/Biochemistry/content.cfm?ItemNumber=40312
International Rubber Study Group. (n.d.). Retrieved June 20, 2017, from
http://www.rubberstudy.com/
Diagram: Natural rubber chemical formula,
http://byjus.com/chemistry/natural-rubber-and-properties/
A block of guayule rubber without carbon black additive.
Photo: Cooper Tire and Rubber,
http://www.toledoblade.com/Automotive/2016/09/16/Cooper-tests-
promising-for-rubber-made-in-U-S.html

6. NEED AND DEMAND FOR ALTERNATIVE
RUBBER SOURCES
• 2006 rubber production deficit was almost 250,000 tons
• >90% of international rubber supply comes from Malaysia, Indonesia and Thailand- sociopolitical and economic
instability
• 50% increase in rubber consumption from 2007 to 2020 forecasted by International Rubber Study Group
• 1.5 to 3 million metric ton shortfall in natural rubber production by 2021
Sources: van Beilen JB, Poirier Y. Guayule and Russian Dandelion as Alternative Sources of Natural
Rubber. 2007; Critical Reviews in Biotechnology. 2007; 27:217-321
International Rubber Study Group. (n.d.). Retrieved June 20, 2017, from http://www.rubberstudy.com/
Photo: Rubber (Official Movie Site),
Magnolia Pictures,
http://www.magnetreleasing.com/rubber/

7. FIRST COMMERCIALIZATION EFFORT
• High price of Amazonian rubber
initiated first effort in early 1900’s
Mexico
• Robust production accounted for 24%
of total rubber imported by US in 1910
• Mexican Revolution ceased production
in 1912
• Concerted effort to relocate operations
across the border to US
• Great Depression halted relocation
efforts in 1929
Photos: Lloyd, Francis Ernest. “The Guayule- A Desert Rubber
Plant.” Popular Science Monthly, vol. 81, Oct. 1912,
en.wikisource.org/wiki/Popular_Science_Monthly/Volume_81/Octo
ber_1912/The_Guayule:_A_Desert_Rubber_Plant.Source: Coffelt T, Ray DT, Dierig DA. 100 Years of
Breeding Guayule. Industrial Crops. 2015; 351-367

8. SECOND COMMERCIALIZATION EFFORT
• Emergency Rubber Project of World War II enacted after Southeast Asian sources of Hevea were cutoff at the beginning
of the war
• Scientists, agronomists, and farmers imprisoned in Japanese internment camps were crucial to research operations and
owed credit for many guayule discoveries
• Effort ceased at the end of the war when natural rubber trade routes were restored and synthetic rubber was developed
Photo: Dorothea
Lange, 1942.
https://phys.org/new
s/2017-03-variety-
guayule-natural-
source-rubber.html
Photo: Dorothea Lange,
1942,
War Relocation
Authority Photographs
of Japanese-American
Evacuation &
Resettlement Collection.
UC Berkeley, Bancroft
Library
https://calisphere.org/ite
m/ark:/13030/ft1c6003c
x/
Source: Finlay, Mark R. "Behind the Barbed Wire of Manzanar: Guayule and the Search for Natural Rubber." Chemical
Heritage Foundation. N.p., 04 Apr. 2017. Web. 26 June 2017. https://www.chemheritage.org/distillations/magazine/behind-
the-barbed-wire-of-manzanar-guayule-and-the-search-for-natural-rubber

9. THIRD COMMERCIALIZATION EFFORT
• Crude oil prices
quadrupled in the late
1970’s
• US fear of oil supply
manipulation or
disruption led to Native
Latex commercialization
and Economic
Development Act (1978)
and the Critical
Agricultural Materials Act
(1984)
• Significant yield increases
and modification to fit
modern mechanized
agriculture
• Interest and effort waned
after political climate
shifted
Source: (1861-1944 WTI,
1945-1983 Arabian Light,
1984-2011 Brent)
Source: Coffelt T, Ray DT, Dierig DA. 100 Years
of Breeding Guayule. Industrial Crops. 2015;
351-367

10. FOURTH COMMERCIALIZATION EFFORT:
PRESENT DAY
• Renewed interest with an estimated 1-6% general
population development of Hevea latex allergy
• Companies foresee sustainability and sociopolitical
issues with Hevea- search for a domestic
alternative for latex and rubber sources
• Unlike previous efforts, current commercialization
is driven by corporations and not government
support
Source: Coffelt T, Ray DT, Dierig DA. 100 Years of Breeding Guayule.
Industrial Crops. 2015; 351-367
Photo: Jesse Chahuk, 2015,
https://www.wired.com/2015/07/superplant-may-finally-topple-
rubber-monopoly/

11. BIOCHEMICAL AND PHYSIOLOGICAL
BACKGROUND OF GUAYULE
• Rubber synthesis pathway still undiscovered
• 2012 study concluded either gene expression
does not control enzymatic activity of rubber
transferase complex and posttranslational
modifications are actual point of control, or
proteins that encode the genes analyzed are
not those regulating rubber biosynthesis
• Guayule rubber synthesis is temperature
dependent, with highest production in cold
months
Source: Veatch-Blohm, M. E., D. T. Ray, and A. Gehrels. "Night Temperature,
Rubber Production, and Carbon Exchange in Guayule." Industrial Crops and
Products 25.1 (n.d.): 34-43. ScienceDirect. Web. 8 June 2017.

12. RUBBER BIOSYNTHESIS
• As mentioned previously, little is known about
the physiological role of rubber synthesis
concerning plant growth. However, rubber
biosynthetic particles (RPs) have been studied
more in depth.
• Rubber biosynthetic rate and polymer size are
primarily regulated by laticifers, long
multinucleate pipes formed from anatomized
cells in latex-producing species (Hevea, F.
elastica, TKS.)*
• In nonlatex plants, such as guayule, which
produces rubber in bark parenchyma cells and
transfers the mature rubber particles into the
vacuole for storage, the regulation rate and
molecular weight has largely devolved to the
rubber transferase enzyme itself.*
Scanning electron micrograph of bark parenchyma cells of stems of
two-year old Parthenium argentatum, showing vacuoles filled with
rubber particles.
Scanning electron micrographs of purified rubber particles.
Photos: Delilah Wood,
USDA,
http://lipidlibrary.aocs.
org/Biochemistry/cont
ent.cfm?ItemNumber=
40312
Source: Cornish, K, Blakeslee, J. Rubber biosynthesis in
plants. 2011; Plant Lipid Biochemistry,
http://lipidlibrary.aocs.org/plantbio/rubber/index.htm

13. DESIRABLE GENETICS
• Heterozygous genetic makeup of
plants in guayule germplasm
collection
• Facultative apomixis in polyploid
guayule continuously releases
new variability with every seed
harvest
Diagram: Quick Reference Apomixis, Amber Lynch for
Bridgestone Agro Operations Guayule Research Farm
Source: Coffelt T, Ray DT, Dierig DA. 100 Years of
Breeding Guayule. Industrial Crops. 2015; 351-367

14. FACULTATIVE APOMIXIS
• Clonal propagation by seed
• Facultative- does not happen all the time
• Sporophytic, self-compatible polyploids
• Frequency of apomictic reproduction can
vary among plants, and even flowers on a
single plant
Source/Diagram: Ray, D.T., D.A. Dierig, and A.E. Thompson. 1990. Facultative apomixis in guayule
as a source of genetic diversity. p. 245-247. In: J. Janick and J.E. Simon (eds.), Advances in new
crops. Timber Press, Portland, OR.

15. GUAYULE:
A COMPARISON
PROS CONS
• High tolerance for drought and
extreme temperatures (-18 to 49.5ºC)
• High genetic variability and diversity
• Early success with breeding high
yielding cultivars- new lines yield up to
250% more rubber than older
midcentury lines
• High resistance to disease and
pestilence
• Domestic plant (native to Texas and
Mexico); removes trade and economic
dependence on unstable foreign
countries
• Other parts of guayule can be used for
a variety of uses (Bagasse, resin, etc.)
• Does not contain the same proteins as
H. brasiliensis that cause allergic
reactions
• Produces high molecular weight
• Extreme
variability
within and
between
lines
• Partially
domesticate
d
• Apomictic
• Perennial that requires relatively large
amounts of land for breeding programs
• Physiologically immature for 2 years
• Asexual reproduction
• Small seeds (1,000-1,500 seeds per
gram)
• Unreliable germination
• Seed dormancy must be broken by
special treatments
• Progenies often fail to repeat high
rubber content of parents
• Transplantation from greenhouse
preferred- direct seeding yields
unreliable results
• Longer transport distances and
increased storage times cause rubber
degradation
Photo: Yulex Corporation,
http://yulex.com/products/guayule/
Sources: Coffelt T, Ray DT, Dierig DA. 100 Years of
Breeding Guayule. Industrial Crops. 2015; 351-367
van Beilen JB, Poirier Y. Guayule and Russian
Dandelion as Alternative Sources of Natural Rubber.
2007; Critical Reviews in Biotechnology. 2007; 27:217-
321
Cornish, K, Blakeslee, J. Rubber biosynthesis in plants.
2011; Plant Lipid Biochemistry, American Oil Chemists
Society.
http://lipidlibrary.aocs.org/Biochemistry/content.cfm?I
temNumber=40312

16. SYNTHETIC RUBBER
• Artificial elastomer made from petroleum byproducts first
developed in early 1900’s
• Prices of synthetic rubber are expected to sharply increase due to
predicted decline in global oil production in the next 10-20 years
• Synthetic rubber industry facing a shortage of butadiene, the
monomer from which 80% of synthetic rubber is produced. This
drives up prices of natural and synthetic rubber
• Synthetic rubber has some advantages over natural rubber- almost
completely waterproof
• Main problem with synthetic rubber- it does not possess the same
thermal distribution properties as natural rubber
• The heat dispersion issue is the main reason an airplane tire cannot
be 100% synthetic- the structure would not hold under these
extreme conditions of heat and pressure
Sources: van Beilen JB, Poirier Y. Guayule and Russian Dandelion as Alternative Sources of
Natural Rubber. 2007; Critical Reviews in Biotechnology. 2007; 27:217-321
Cornish, K, Blakeslee, J. Rubber biosynthesis in plants. 2011;
Plant Lipid Biochem, http://lipidlibrary.aocs.org/plantbio/rubber/index.htm
Photo: Getty Images, https://www.wired.com/2016/08/airplane-tires/

17. GUAYULE’S COMPETITION:
THE RUSSIAN DANDELION
• Taraxacum kok-saghyz
• Discovered in Kazakhstan in early 1930’s
as part of Soviet program to produce
domestic source of rubber
• Cultivation during midcentury USSR
programs was labor intensive and
expensive- extensive tilling necessary due
to weeds overtaking the small seedlings
• Species has a self-incompatibility system,
preventing self-fertilization
• Soviet programs were terminated with
the end of World War II due to high cost
of production ($44/kilogram in the
1940’s)Source: van Beilen JB, Poirier Y. Guayule and Russian Dandelion as Alternative
Sources of Natural Rubber. 2007; Critical Reviews in Biotechnology. 2007; 27:217-
321
Photo: Uli Benz, Technical University of München, https://phys.org/news/2015-04-rubber-
dandelions-scientists-key-components.html

18. TARAXACUM KOK-SAGHYZ
• Short life cycle (annual, 6-8 months)
• Modern-day resurgence as an
alternative to Hevea rubber
• DuPont, Bridgestone, Cooper and
Continental Tire are involved in various
TKS projects
• Full-scale development and
commercialization would require
building up molecular tools such as
BAC libraries, RNAi silencing,
microarrays, etc.
• Laticifers (distinct cell linkages
containing latex and rubber particles)
still need further research
Source: van Beilen JB, Poirier Y. Guayule and Russian Dandelion as Alternative
Sources of Natural Rubber. 2007; Critical Reviews in Biotechnology. 2007; 27:217-
321
Photo: Dandelion field, http://landscapermagazine.com/wp-
content/uploads/2015/08/dandelions-field.jpeg

19. PARTHENIUM ARGENTATUM
VERSUS
TARAXACUM KOK-SAGHYZ
Source: JB van Beilen and Y Poirier (2007) Guayule and Russian Dandelion as
Alternative Sources of Natural Rubber, Critical Reviews in Biotechnology, 27:4,
217-231.

20. THE SACATON PROJECT
• Department of Defense issued $20 million research grant to Gila
River Indian Community in Sacaton, Arizona
• 206 acres of guayule planted by 1986
• Low rubber yield and worries about paying back the loan led to
USDA takeover of Sacaton project
• In 1986, USDA contracted Firestone Tire and Rubber to produce 54
tons of guayule rubber in conjunction with Sacaton project
• Firestone’s pilot guayule processing plant completed in 1988
• Bridgestone acquired Firestone in 1988 for $2.6 billion
• Solvent leaks, contaminated latex, and other problems arose; both
the Sacaton project and the Firestone plant closed in 1991
Sources: EU-PEARLS 2010 W.W. Schloman, Jr.
https://www.researchgate.net/profile/W_Schloman/publication/312040009_Guayule
_Rubber_Production_at_Sacaton_Arizona_1987-
1990/links/586bca3e08ae329d621213d7.pdf?origin=publication_detail
Moore, Miles. “Guayule, Russian Dandelion through the Years.” Rubber & Plastics
News, 12 June 2013, www.rubbernews.com/article/20130607/NEWS/130609960.

21. BRIDGESTONE:
A RENEWED COMMITMENT
Source: Bridgestone Biorubber Process Research Center Grand
Opening. Bridgestone Corporation, 22 Sept. 2014,
www.youtube.com/watch?v=KkTopAcOqJI.

22. BRIDGESTONE AGRO OPERATIONS
GUAYULE RESEARCH FARM
• Eloy, Arizona
• Established in
2013
• 281 acres
• Two greenhouses
• Onsite laboratory
• 17 employees
Source: “From Seed to Tread: Bridgestone Reveals First Tires Made Entirely of Natural Rubber
Components from Company’s Guayule Research Operations.” Bridgestone Global Website,
Bridgestone Corporation, 1 Oct. 2015,
www.bridgestone.com/corporate/news/2015100101.html.

23. BRIDGESTONE BIORUBBER PROCESS RESEARCH CENTER
• Mesa, Arizona
• Established in 2014
• 8,300 ft² office and
laboratory
• Four platform, 3,500 ft²
shrub prep building
• 5,500 ft², two-level
process building for
rubber extraction, co-
product and solvent
recycling
• 3,100 ft² mechanical and
electrical building
Source/Photos: “Bridgestone Begins Producing Natural Rubber in Mesa,
Arizona.” Bridgestone Americas, Inc., 22 Sept. 2014,
www.bridgestoneamericas.com/en/newsroom/press-releases/2014/bridgestone-begins-

24. RUBBER EXTRACTION PROCESSES
Flotation/Saltillo Extraction
•Ground shrubs are placed in a large
vat of dilute sodium hydroxide until
the woody tissue takes up water and
sinks to the bottom and the resinous
rubber floats to the top in what are
called “worms” . These worms are
skimmed from the top and the rubber
is deresinated with acetone.*
•Used in Mexican guayule processing
facilities until 1990.
Sequential Extraction
•Resin is first extracted with acetone or
another polar organic solvent, and
then the rubber is extracted with
hexane. *
•Does not appear to be an
economically viable method.
•Does not assure the selective recovery
of the high-molecular weight fraction
of the rubber polymer*
Simultaneous Extraction
•A mixture of solvents, usually acetone
and hexane/pentane are used. After
the initial extraction, more acetone is
added to coagulate the high
molecular weight rubber. *
•Current method of extraction for
Bridgestone.
•Option to fractionate the rubber is
provided, unlike Sequential Extraction
Sources:
Schloman, W. W. “Processing
Guayule for Latex and Bulk
Rubber.” Industrial Crops and
Products, no. 22, 21 Apr. 2004,
pp. 41–47. Science Direct.
Ray, D.T. Guayule: A Source of
Natural Rubber. New Crops.
1993; 338-343
Photo: Bridgestone Americas, courtesy of Green Chemicals Blog.
https://greenchemicalsblog.com/2013/05/22/bio-rubber-
developments/

25. FLOTATION/SALTILLO PROCESS
Diagram: The Firestone Tire and Rubber Company (1987).
Process for extracting rubber and by-products from guayule
and guayule-like shrubs. EP0039910 B1.
Photo: Ansel Adams, 1943,
Library of Congress Prints and
Photographs Division, LC-DIG-ppprs-
00301

26. SIMULTANEOUS EXTRACTION
Diagram: The Firestone Tire and Rubber Company (1987). Use of rubber solvent-
resin solvent and miscella mixtures for extraction-expression of rubber and
resins from guayule shrub. US4681929 A.
Guayule bale on display at the Biorubber Process Research Center in
Mesa, AZ.
Photo: Jim Motavalli, 2014. https://www.mnn.com/green-
tech/transportation/blogs/bridgestone-is-growing-tires-in-the-

27. SIMULTANEOUS EXTRACTION PROCESS:
IN DEPTH
1. Shrub is sliced into 3-4cm pieces
2. Small pieces are sent through a flaker to flatten and shear shrub tissue which ruptures cells containing
rubber
3. Flaked shrub combines with extraction solvent¹ at 50°C to form slurry. Bagasse separates from the
miscella by a continuous screen bowl centrifuge. A percentage of the miscella is recycled and returns to
the extraction system to function as the rubber solvent.
4. Rubber fractionation is a multi-stage operation involving a series of five mixer-settler units. *
1. Miscella is mixed with acetone to thicken rubber, which is precipitated out and settles to the bottom of the mixer-settler.
2. The lighter liquid phase containing most of the resin is pumped continuously from the top of the unit.
3. The coagulated rubber is then pumped through the down-stream mixer-settler units, where a mixture of pentane or
hexane and acetone capable of dissolving both resin and low-molecular weight rubber is pumped counter-current to the
rubber-containing phase.
4. This strips the rubber phase of its resin and low-molecular weight rubber components.
5. The solvent-swollen, high molecular weight rubber phase was pumped from the bottom of the fifth-stage mixer-settler
unit. The stream containing the extracted resin and low-molecular weight rubber is decanted from the top of the second
stage mixer-settler.
5. The swollen rubber phase passes through a twin-screw extruder-devolatizer that uses a combination of
heat and reduced pressure to strip off the solvent. The extruded rubber product is compressed into
solid rectangular bales weighing 30-35 kg.*
Source/Diagram: W.W. Schloman, Processing guayule for latex
and bulk rubber, Industrial Crops and Products, Volume 22,
Issue 1, 2005, Pages 41-47, ISSN 0926-6690,
http://dx.doi.org/10.1016/j.indcrop.2004.04.031.
NOTE: While Bridgestone’s
current rubber extraction process is
highly confidential, the
Firestone/Sacaton Project’s general
extraction methods and diagrams
were published in a paper by W.W.
Schloman in 2004.
¹Acetone-pentane azeotrope or acetone-hexane mixture. Primary extraction medium was recycled
rubber-resin miscella.

28. GUAYULE
• Bagasse- fibrous, leftover plant material
for feedstock
• Resin- fatty acid triglycerides and
terpenoids for rubber additives, wood
preservative
• Inulin- storage carbohydrate (fructan)
for non-food applications or
fermentation into bioethanol
• Glucose- simple sugar for biogas
production
• Dandelion greens- plant material for
human consumption
TKS
INDUSTRIAL CROP BYPRODUCTS
(EXCLUDING RUBBER)
Photo: Dandelion in traffic,
http://www.ourherbgarden.com/her
b-history/dandelion-history.html

29. GUAYULE GROWING AREAS
Suitable U.S. Growing Areas
• California: 2,435,000 acres
• Arizona: 682,000 acres
• New Mexico: 895,000
acres
• Texas: 17,556,000 acres
Suitable Eastern Hemisphere
Growing Areas
• Spain
• France
• Italy
• Greece
• Turkey
• Israel
• Morocco
Sources: Bridgestone Agro
Operations Guayule
Research Farm
“European Natural Rubber
Substitute from
Guayule.” European
Commission, 1 Feb. 2015,
ec.europa.eu/growth/tools-
databases/eip-raw-
materials/en/content/europ
ean-natural-rubber-
substitute-guayule.

30. PRECISION AGRICULTURE
Drones measure plant canopies
and leaf temperature
Barcode scanners
streamline tagging and
identification process
High Throughput Phenotyping
tractor measures row width,
distance, leaf temperature and
moisture

31. Diagram: Mark Cruz for Bridgestone Agro Operations Guayule Research Farm

32. BRIDGESTONE AND UNIVERSITY OF ARIZONA:
COLLABORATIVE USDA GRANT PROJECT
Bridgestone and University of Arizona
are studying rubber content of USDA and
Bridgestone guayule lines. Plants were
pollinated, labelled and bagged biweekly. Seed
was collected from pollinated flowers 4-6 weeks
after crossing. Heavy monsoon rains did impede
pollination and collection for the majority of July.
Photo: Mark Cruz for Bridgestone Agro
Operations Guayule Research Farm, June
2017.

33. BRIDGESTONE RESEARCH:
LEAF AREA PAPER
Dr. David Dierig (Section Manager) and Dr.
Von Mark Von Cruz (Plant Breeder) began working on
a paper this summer analyzing leaf area differences on
the guayule USDA lines.
Five old leaves and five new leaves were
collected from five plants of each line (41USDA lines
planted at Bridgestone, 52 lines total in USDA seed
vault). Selections were made to ensure no
biotic/abiotic damage to samples for proper analysis.
All guayule leaves were pressed for 24 hours to ensure
accurate serration and area measurements.
Leaves were scanned into PDF format, then
individually cropped to be analyzed by MorphoLeaf
software.To ensure area data accuracy, leaves were
also individually analyzed on a Licor Leaf Area Meter.
Photos: Kelly McDowell for Bridgestone Agro Operations Guayule Research
Farm
LineN396,Plant#302,oldLineAZ2,Plant#01,
old
LineCFS24,Plant#264,
old

34. MORPHOLEAF SOFTWARE
MorphoLeaf is a free software
allows users to extract the outline of leaf
images and identify biologically-relevant
points of interest. The software
quantifies morphological parameters of
leaves and then reconstructs average
leaf forms.
Source/Photo: MorphoLeaf Software,
http://morpholeaf.versailles.inra.fr/#features
Arabadopsis analysis example- extraction of leaf tip and
teeth sinuses

35. Preliminary results from
average area analysis
Source: Bridgestone Agro
Operations Guayule
Research Farm
Possible results from analysis for future use:
 Rubber/latex yields
 Drought tolerance
 Photosynthesis, Photosynthetic Active Radiation, Daily Light Integral and Specific Leaf Area
 Biomass productivity (direct correlation)
 Leaf shape characteristics: variations, benefits, i.e. leaf wax, trichomes