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

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

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

8. Genomes and species relationships
in genus Arachis

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

11. Challenges to producing Arachis interspecific
hybrids and germplasm introgression

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)

13. Pathways of Germplasm Introgression
• Triploid-Hexaploid Route
• Tetraploid Route
• Autotetraploid
• Amphidiploid

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

17. Greenhouse and Field evaluations of
interspecific hybrid derived breeding lines

18. Most common groundnut diseases in NC are
Early leaf spot Late leaf spot Web blotch
CBR Sclerotinia TSWV

19. 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)

21. 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

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

24. Pod Yield (lb/A)
0
500
1000
1500
2000
2500
3000
3500
SPT 04-05 5.20 3107
HTS 02-03 5.84 3034
HTS 02-01 4.57 3026
SPT 04-06 4.48 2974
HTS 02-10 4.47 2939
SPT 04-08 4.52 2830
HTS 02-06 4.65 2818
HTS 02-07 5.95 2790
SPT 04-07 5.18 2789
SPT 04-03 5.20 2736
HTS 02-04 4.78 2710
HTS 02-02 4.54 2642
SPT 04-10 5.69 2559
SPT 04-02 5.36 2547
SPT 04-04 5.14 2487
SPT 04-01 4.39 2479
HTS 02-08 4.20 2442
SPT 04-09 6.16 2298
SPT 04-12 4.48 2267
HTS 02-09 5.19 2249
HTS 00-02 4.07 2239
SPT 04-14 6.26 2207
Line
SPT 04-13 6.37 2139
HTS 03-01 6.66 2063
SPT 04-11 6.04 2044
HTS 02-05 5.22 1992
Brantley 6.48 2686
Phillips 6.26 2618
NC 12C 6.31 2530
Perry 6.22 2410
Unsprayed leaf spot test (2005-08)
Gregory 6.99 2387
NC-V 11 7.18 2303
NC 7 6.52 2230
Wilson 6.79 2213
VA-C 92R 7.04 2181
NC 6 7.05 1897
VA 98R 7.06 1883
GP-NC 343 4.60 3335
PI 269685 2.95 2890
PI 121067 3.16 2537
Kanyoma 4.75 2454
PI 270806 4.88 2185
PI 109839 4.45 1831
0
2
4
6
8
10
12
14
16
Defol. score

25. Grade characteristics of cultivars and selected breeding lines
derived from interspecific hybrids
Avg.
pod
Bright- Pod
Cultivar/ ness Meat Yield
Line (Hunter L) (%) (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

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

27. Disease inoculations
CBR Sclerotinia
TSWV

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 - - -

31. 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

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

33. Ideas for Cassava Improvement

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