Genomes and species relationships in genus Arachis,Challenges to producing Arachis interspecific hybrids and germplasm introgression,Greenhouse and Field evaluations of interspecific hybrid derived breeding lines,Ideas for Cassava improvement
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Groundnut and Cassava,The underground mystery: What can a breeder do?
1. Groundnut and Cassava
The underground mystery:
What can a breeder do?
S. P. Tallury
Department of Crop Science
NC State University
Raleigh, NC 27695-7629
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6. Overall goal of my program is
To develop multiple disease resistant
groundnut cultivars
Specific goal is,
To transfer multiple disease resistances
available in diploid wild species into
susceptible cultivars
7. Outline
• Genomes and species relationships in
genus Arachis
• Challenges to producing Arachis
interspecific hybrids and germplasm
introgression
• Greenhouse and Field evaluations of
interspecific hybrid derived breeding
lines
• Ideas for Cassava improvement
9. Genus Arachis has nine sections and A. hypogaea
belongs to section Arachis
Section Arachis has diploid (2n=2x=20),
tetraploid (2n=4x=40) and aneuploid (2n=2x=18)
species
Species in section Arachis cross relatively
easily with A. hypogaea resulting in hybrid pegs/
seeds
Potential disease resistant species are diploid
and crossability with A. hypogaea varies from
0-5%
10. • A. hypogaea is an allotetraploid with two
different genomes (A and B) in it‟s make
up
• „A‟ genome is characterized by a small
chromosome pair and „B‟ genome which
lacks the small pair of chromosomes
A genome B genome
12. Critical issues in interspecific hybridization are
1) How to improve the efficiency of hybrid
production/development? (Incorporation)
2) How to induce/improve the efficiency of
recombination between parental chromosomes?
(Introgression)
14. AA BB AA
10 10 10 10 10 10
x
Cultivated Peanut Wild Species
2n = 4x = 40 (Tetraploid) A A B 2n = 2x = 20 (Diploid)
10 10 10
Sterile Triploid F1 hybrid
2n = 3x = 30
Colchicine treatment
AA AA BB
10 10 10 10 10 10
Hexaploid hybrid
2n = 6x = 60
self 10 or more generations
AABB AABB
Tetraploid Introgression Lines
15. 2n=4x=40 2n=2x=20
0.2% Colchicine for 6-8 h
2n=3x=30 2n=6x=60
16. Tetraploid Route
Species A Species A x Species B
(2x) (2x) (2x)
F1 hybrid (2x)
Colchicine Colchicine
Autotetraploid x A. hypogaea x Amphidiploid
(4x) (4x) (4x)
4x 4x
22. Lines were evaluated independently in
side-by-side spray-controlled and
unsprayed field tests for early leaf spot
Estimates of defoliation percentage and
visual ratings were made on a plot basis
with 1 = no disease to 9 = dead plants
Plot yield was measured by weighing all
pods harvested and yield estimates were
made
26. Flavor profiles of 16 different ELS resistant
interspecific hybrid breeding lines along with the
industry flavor standard, NC 7, were analyzed
None of the breeding lines were significantly
different from NC 7 in flavor quality
28. AUDPC for Sclerotinia and CBR root rot
scores of selected cultivars and
interspecific breeding lines
CBR
Line AUDPC Score*
Gregory 92.8 20.5 3.64 ±0.34
Perry 94.7 ±20.5 3.57 ±0.34
N96076L 57.6 ±17.7 4.06 ±0.28
SPT 06-07 6.4 ±35.8 3.62 ±0.48
HTS 02-01 67.8 ±38.8 3.39 ±0.48
SPT 06-03 82.9 ±35.8 3.22 ±0.48
SPT 04-06 48.5 ±35.8 3.05 ±0.48
*0 = Clean root 5 = Completely rotted root
29. TSWV Evaluations (2005-07)
110 plots from A. hypogaea x A. cardenasii
were evaluated for TSWV resistance in
field tests at Lewiston, NC
Dead/diseased plants were counted in
plots every 2-weeks beginning in early
June until 2 weeks before harvest
22 whole plots were selected for field
resistance to TSWV
30. Yield and Disease Evaluations of Interspecific Hybrid Derived
Breeding lines and Cultivars at PBRS, Lewiston, NC, 2005-08
ID Defol. Score Pod Yield W/out CBR SB TSWV
(1=none to 9=complete) leaf spot control (lb/A)
Brantley 6.4 2742 - S -
Champs 5.8 3244 C - -
Gregory 6.4 2493 - - -
Perry 6.3 2497 - - -
Phillips 6.4 2551 - - -
VA 98R 7.0 2277 - S -
Wilson 6.5 2786 - - -
HTS 00-02 4.1 2673 - - T
HTS 02-01 4,3 3449 C S -
HTS 02-02 4.3 3226 - S -
HTS 02-03 5.6 3077 - - -
HTS 02-04 4.7 2933 - - -
HTS 02-05 5.0 2274 - - -
HTS 02-06 4.3 3376 - - -
HTS 02-07 5.9 3017 - - -
HTS 02-08 4.0 2724 C S -
HTS 02-09 4.8 2624 C S -
HTS 02-10 4.3 3103 - - -
HTS 03-01 5.3 2910 - - -
SPT 04-01 4.0 2678 - - -
SPT 04-02 4.8 2971 - - -
SPT 04-03 4.7 3242 - - -
SPT 04-04 4.5 2967 - - -
SPT 04-05 4.4 3145 C S -
SPT 04-06 4.3 3114 - - -
SPT 04-07 4.9 3156 C S -
SPT 04-08 4.3 3138 - - -
SPT 04-09 5.4 2951 - - -
SPT 04-10 5.5 2983 - - -
SPT 04-11 5.5 3134 - - -
SPT 04-12 4.2 2276 C S -
SPT 04-13 5.8 2742 - - -
SPT 04-14 5.7 2311 - - -
SPT 06-01 4.0 3396 - - -
SPT 06-02 4.2 2276 - - -
SPT 06-03 4.6 3264 - S T
SPT 06-04 3.5 2777 C S -
SPT 06-05 4.3 1983 - - -
SPT 06-06 3.1 2861 C S T
SPT 06-07 3.0 2986 C S T
SPT 06-08 4.2 3550 - - T
SPT 06-09 4.5 2773 - - -
SPT 06-10 4.5 2859 - - -
32. Overall Conclusions
Successfully transferred multiple disease
resistance
Yield and grade characteristics were competitive
Selected set of breeding lines will be evaluated in
PVQE in 2009
Promising lines will be evaluated in multi-state
(VA, NC and SC) trials in 2010 before considered
for release
34. Steps in Cassava germplasm enhancement pipeline
Acquire Evaluate Transfer Deploy
Field breeding and evaluations
Marker Assisted Selection
Courtesy of Dr. Kuraparthy
35. Traits of concern for Cassava breeding
1. Susceptibility to diseases
2. Highly heterozygous
3. Vegetative propagation
4. Variable flowering patterns
5. Low seed set and seed dormancy
6. Lack of genetic studies about inheritance of
useful traits (HCN levels in Manihot species?)
36. Hybrid Seed Production and Inbreeding
Concerns
Gene segregation from favored heterozygotes to
unfit homozygotes
Too drastic that the inbreds may not survive
Developing inbreds by successive selfing takes
> 10 y
Solution: Doubled Haploids?
37. Inbred vigor can be improved by a few recurrent
selection cycles (Sibbing elite clones to S2 and
recombining the surviving progenies) as
suggested by
Tallury, S. P. and Goodman, M. M. (2001) in
“Broadening the genetic base of crop plants”
CAB publication
38. Short term goals (1-3 years)
• Continue evaluation of existing
materials and explore possibilities for
hybrid seed production
• Evaluate Manihot species for disease
resistance and other traits
Greenhouse inoculations
Molecular markers using BSA
• Characterize species genomes by
Crossability
Karyotyping and
DNA fingerprinting
• Initiate interspecific crosses to broaden
the germplasm base
39. Long term goals (3-5 years)
Specifically, I would
• Attempt to produce a large # of
triploid hybrids
• Also, produce amphidiploids to use
in bridge crosses
• Greenhouse/lab and field evaluations
for inbred line development and
hybrid production
40. Vision for Cassava Research
Breeding
Genetic Diversity Develop superior Cooperators
germplasm
Evaluate Distribute
germplasm germplasm
Cassava Improvement
Molecular
Fingerprinting
Genetic Mapping Training
Sequencing of genes