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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?
S. P. Tallury
Department of Crop Science
NC State University
Raleigh, NC 27695-7629
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
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
Genomes and species relationships
in genus Arachis
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%
• 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
Challenges to producing Arachis interspecific
hybrids and germplasm introgression
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)
Pathways of Germplasm Introgression
• Triploid-Hexaploid Route
• Tetraploid Route
• Autotetraploid
• Amphidiploid
Cultivated Peanut Wild Species
2n = 4x = 40 (Tetraploid) 2n = 2x = 20 (Diploid)
A A B B A A
A A B
A A A A B B
Hexaploid hybrid
2n = 6x = 60
Sterile Triploid F1 hybrid
2n = 3x = 30
AABB AABB
Colchicine treatment
self 10 or more generations
Tetraploid Introgression Lines
10 10 10 10 10 10
10 10 10
10 10 10 10 10 10
x
2n=4x=40 2n=2x=20
2n=3x=30 2n=6x=60
0.2% Colchicine for 6-8 h
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
Greenhouse and Field evaluations of
interspecific hybrid derived breeding lines
Most common groundnut diseases in NC are
Early leaf spot Late leaf spot Web blotch
CBR Sclerotinia TSWV
Species Resistance
A. cardenasii Leaf spots, CBR, Sclerotinia blight
(10017) TSWV, nematodes, several insects
A. diogoi Leaf spots, rust, TSWV, insects
(10602)
A. correntina TSWV and Sclerotinia blight
(9530, 19616)
A. duranensis Aflatoxin
(30060, 30064, 30073)
Early Leaf Spot Evaluations
at Lewiston (2005-08)
26 Tetraploid (2n = 4x = 40)
interspecific hybrid derived
breeding lines
11 Commercially grown susceptible
Virginia-type cultivar checks
7 Resistant A. hypogaea checks
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
Unsprayed leaf spot test (2005-08)
3107
3034
3026
2974
2939
2830
2818
2790
2789
2736
2710
2642
2559
2547
2487
2479
2442
2298
2267
2249
2239
2207
2139
2063
2044
1992
1831
2185
245425
37
2890
3335
1883
1897
2181
2213
223023
032387
241025
30261826
86
5.20
5.84
4.57
4.48
4.47
4.52 4.65
5.95
5.18
5.20
4.78
4.54
5.69
5.36
5.14
4.39
4.20
6.16
4.48
5.19
4.07
6.26 6.37 6.
66
6.04
5.22
6.48
6.26
6.31
6.22
6.99 7.
18
6.52 6.
79 7.04
7.05
7.06
4.60
2.95 3.
16
4.75 4.88
4.45
0
500
1000
1500
2000
2500
3000
3500
SP
T 0
4-05
HT
S 0
2-03
HT
S 0
2-01
SP
T 0
4-06
HT
S 0
2-10
SP
T 0
4-08
HT
S 0
2-06
HT
S 0
2-07
SP
T 0
4-07
SP
T 0
4-03
HT
S 0
2-04
HT
S 0
2-02
SP
T 0
4-10
SP
T 0
4-02
SP
T 0
4-04
SP
T 0
4-01
HT
S 0
2-08
SP
T 0
4-09
SP
T 0
4-12
HT
S 0
2-09
HT
S 0
0-02
SP
T 0
4-14
SP
T 0
4-13
HT
S 0
3-01
SP
T 0
4-11
HT
S 0
2-05
Bra
ntle
yP
hilli
psN
C 1
2CP
erry
Gre
gory
NC
-V 1
1N
C 7
Wils
onV
A-C
92R
NC
6V
A 9
8RG
P-N
C 3
43P
I 269
685
PI 1
2106
7K
anyo
ma
PI 2
7080
6P
I 109
839
Line
Po
d Y
ield
(lb
/A)
0
2
4
6
8
10
12
14
16
Def
ol.
sco
re
Grade characteristics of cultivars and selected breeding lines
derived from interspecific hybrids
Cultivar/
Line
Avg.
pod
Bright-
ness
(Hunter L)
Meat
(%)
Pod
Yield
(lb/A)
NC 12C 80.2 74.4 44.9 37.0 68.0 71.2 2530
NC-V11 76.3 70.7 44.5 23.5 67.6 70.8 2303
Gregory 87.6 83.1 44.3 41.5 67.2 70.5 2387
Perry 87.5 86.9 42.9 32.9 66.4 69.6 2410
VA 98R 79.2 73.0 44.4 25.4 65.4 70.0 1883
HTS 02-01 81.4 84.3 42.6 31.7 66.4 68.9 3026
HTS 02-02 74.7 79.9 43.2 26.2 60.9 64.7 2642
SPT 04-06 77.9 91.4 43.5 36.5 67.5 70.5 2974
SPT 04-05 71.1 55.3 44.3 27.1 66.3 68.7 3107
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
CBR Sclerotinia
TSWV
Disease inoculations
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
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
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 - - -
AYT at Lewiston, NC, 2007-08
ID Pod Yield (lb/ac)
GG/WS15 3033
GG/WS15 2624
SPT 06-06 3380
DL1/C99R/WS12 3713
SPT 06-01 3827
HTS 02-01 4091
SPT 04-02 4001
NC-V11/01LSP14 4409
NC12C/WS15 4908
Perry/WS12 3494
Perry/WS12 3464
VA98R/00BLSS12/Chico/00BLSS12 4243
VA98R/01LSP14 3955
VA98R/01LSP14 4258
SPT 06-07 4258
SPT 04-05 3713
UF97318//UF97318/NC343 3592
SPT 04-06 4916
Gregory (Check) 2397
Phillips (Check) 4379
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
Ideas for Cassava Improvement
Steps in Cassava germplasm enhancement pipeline
Acquire Evaluate Transfer Deploy
Marker Assisted Selection
Field breeding and evaluations
Courtesy of Dr. Kuraparthy
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?)
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?
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
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
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
Vision for Cassava Research
Cassava Improvement
Evaluate
germplasm
Develop superior
germplasmDistribute
germplasm
Fingerprinting
Genetic Mapping
Sequencing of genes
Training
Genetic Diversity
Molecular
Breeding
Cooperators