Population genetics and high-value hardwoods: Potential for Acacia

Report
THE RIGHT KOA FOR YOU…..
Charles H. Michler
Director, Tropical Hardwood Tree
Improvement and Regeneration
Center
Acknowledgments
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Paul Scowcroft
JB Friday
Christian Giardina
Nick Koch
Mike Robinson
Travis Idol
Nick Dudley
Katie Friday
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James Brewbaker
Creighton Litton
Bob Masuda
Aileen Yeh
Cheyenne Perry
Tom Baribault
Michael Constantinides
Different kinds of koa
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Canoe logs
Elite timber trees
Ecological habitat
Genetic diversity
Adapted to different climates (dry, wet, cold,
frost, etc.)
• Wilt resistant
• Insect resistant
Population Genetics
Taking advantage of genetic variation that exists
within a population or between populations to
produce trees or stands with desired suite of traits
Within
Between
Productive plantations/natural forests occur when you:
Match the genetics of the desirable trees with sites where
they are well-adapted and then apply good silviculture
Population Considerations
• Tend to not want to move populations greater than 1000 ft.
in elevation, but this needs to be tested in the case of koa.
– Biggest problems occur when you move material from
a higher to lower elevation
• Don’t move populations from areas that have little
environmental variation (rainfall, temperature, etc.) to
sites that have much variation.
• Tetraploidy makes it more difficult to predict heritability,
but it can be done.
• Long term retention of seed bank can prevent loss of
genetic variation due to high-grading (continually harvest
the best trees) and alternate land use.
Sources of Population Variation
• Mutations
– Unique trait appears such as nut shape, branch angle, or
figured wood
• (Natural) Selection of the fittest
– Loss of trees that cannot compete
• Gene flow between populations
– We take advantage of this in seed orchards by using
parents from different populations
Needs for Genetic Improvement
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Straightness and lack of forking
Volume increase
Wood density???
Crown architecture???
Insect tolerance (Acacia psyllid)
– Might be accomplished through management
• Vascular wilt tolerance (Koa wilt)
– Often accomplished through resistance of a vector if
the disease is mediated in this manner
• Other traits??
Expectations from Genetic
Improvement
• 2-4%/year gain (20-25% per selection cycle)
– Much higher through genomic technologies (if
funds are available)
• Highly heritable
– Straightness
– Branch angle
– Volume
– Pest resistance (can be)
Possible limitations to consider
• Type of pollinators and weight of pollen (short
wind driven distance) could limit genetic
diversity between separated populations
– On the mainland, pollinators in many forested
landscapes are becoming or have become absent
• Seed orchard design still unclear for insect
pollinated species (we augment pollinators
when they are limiting)
Uses of Vegetative Propagation
(grafting, rooted cuttings, tissue culture, air layering, etc.)
• Preserve important trees
• Multiplication of important trees for further
testing
• Deploying elite clones to capture maximum
genetic gain
Nick Dudley, HARC
Development of Wilt resistant koa for Hawai΄i
• Moderate to high mortality in mid to low elevations
• Screening families at the seedling stage
• Developing seed orchard lots to examine durability of field
resistance
• Developing resistant populations across most islands and
growing zones
• Using tissue culture to bank resistant lines
Development and selection of high quality koa
using McIntire-Stennis funds at UH-M
(Turano, Brewbaker, Friday, Idol, and DeFrank)
• Evaluate koa progeny for color and figure
• Develop methods for cloning koa/propagate superior
clones
• Plant clonal orchards at various locations
• Genotype high quality accessions
• Determine wood quality of young koa trees
• Determine ultrastructure of figured wood
IDENTIFYING THE PRIME TIMBER TREES
KS trees that will be
thinned into a seed
orchard
HARC A SITE
After data analysis and thinning (Forest Solutions)………Ready for progeny testing of
best families on DHHL land
Will analyze
wood quality
differences
among families
and also the
genetics of seeds
in a single pod
(one pollen grain
may fertilize all
eggs in a pod)
Nick Dudley/Aileen Yeh initiated planting and Oriana Krauss/Keith Woeste
measured/analyzed
Matching
koa
seedlings to
the correct
elevation
Low frost tolerance
Moderate frost tolerance
High frost tolerance
Objectives: 1) Estimate variation in genetics between koa populations
in various regions of the Big Island, 2) Evaluate genes vital for survival at
varied latitudes in a changing climate, 3) Use NexGen sequencing to
identify and characterize genes responsible for critical variations in koa
populations.
SITE LOCATIONS
Kaua’i
Ni’ihau
Waimea
Kohala
Hualalai
Kona
P
H
Moloka’i
Lana’i
Kaho’olawe
B
Mauna Kea
O’ahu
Maui
Hilo
Hawai’i
(Big Island)
M
Mauna Loa
Kilauea
Volcanoes National
Park
Fig. 1. Site Identification and Elevation.
B= Bird Corridor (>7,000 ft )
P= Kipuka Pu’U (6700–6800 ft)
H= Hark A (6600–6700 ft)
M= Nine Mile (2200–2400 ft)
Which genes involved in survival allow certain Acacia
koa to survive at higher altitudes while others perish?
Koa tree survival at varied elevations.
Seedpods are usually most viable within 1000 ft
of their mother tree.
Upper Range
Limit
Without koa trees for nesting,
endangered birds are pushed towards
extinction
Example: Seedling adaptability range
Not adapted = > 1,000 ft north
M Growth range =
1,000 ft
Not adapted = > 1,000 ft south
Koa can grow at lower elevations however, wilt disease has
decimated remaining trees
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Next Generation Sequencing (NGS)
Phyllode
Bipinnate leaflets
Compilation and analysis of NGS datasets. RNA extracted
from koa phyllodes was used for NGS to aid in sequence and
gene identification.
Which genes are involved in or responsible for the formation of
figure in Acacia koa trees ? Why are some “neighbor” trees
unexceptional?
Low Quality
Figure
Harvest
$4 – $8 bd ft
A
B
A
B
A
High Quality
Figure
$100 – $150 bd ft
B
Growth Conditions
Elevation
Precipitation
Insects
Soil content
Herbivores
Sunlight
Figure formation in wood. Koa growth is made exceedingly complicated
by the differences seen in wood from the sawn trees grown under
identical conditions.
Identify genetic variation between various koa populations
Evaluate genes vital for survival in a changing climate
Assemble the first koa genome sequence available for public use
Uncover data useful in koa forest restoration for support of
endangered native bird species
'I'iwi
(Vestiaria coccinea)
'Akiapola'au
(Hemignathus munroi)
Koa trees also provide habitat for birds species found only
in Hawai’i
Scarification and
removal of
invasive grasses
leads to habitat
restoration .
Invasive grasses prohibit growth
Decreased grass cover improves
growth
James Leary et al.
Improved
Wild tree
Proposed Planting Design with Focus on Crop Trees
Lessons Learned: Plantation
prescriptions
• Increase stand density—could be large increase
for Koa
• Mixed tropical hardwood species
– Silvicultural trials looking at competition
• Start planting with focus on end result
– Invest in crop trees or invest in the ecology
• Start with most appropriate seed---the right
provenance
What’s needed to be successful
• Long term commitment (Foundation)
• Knowledge of basic biology of the species (much to
learn)
– Flowering, seed biology, physiology
• Operational and developmental (research)
components
• Land for testing
• Funds for staff, equipment, infrastructure, and
supplies
• Maintained focus (constant worthy suggestions)

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