grm 2013: improving and deploying markers for biotic stresses in cassava -- c egesi

Improving and deploying markers for biotic stresses in cassava

GCP Project #: G7010.01.02

Chiedozie Egesi NRCRI, Nigeria

Biotic constraints of cassava in Africa Mapping and new QTLs for cassava mosaic disease

(CMD) Pyramiding of QTLs for CMD Validating QTLs for cassava brown streak disease

(CBSD) Mining for resistance genes for cassava bacterial

blight (CBB) and cassava green mite (CGM) Summary

Outline

Cassava brown streak disease Cassava bacterial blight

Cassava mosaic disease Cassava green mite

Each could cause yield losses of 30 to 100%

Major Biotic Constraints in African Cassava Productivity

To develop mapping populations for CMD

To identify and map QTLs for new sources of CMD

To develop populations for validation of QTLs for CBSD

To identify sources of resistance to CGM and CBB

Specific Objectives

New QTLs for CMD

Umudike: 97/2205 x 30555 N=340

Frequency distribution of severity scores for CMD in 2 mapping populations in Umudike and Otobi

Otobi: 96/1089A x 30555

Otobi: 97/2205 x 30555

Umudike: 96/1089A x 30555 N=141

Disease severity scores from 1 to 5. Plants with scores 1-2 are considered resistant.

Mean symptom severity scores for CMD in 2 mapping populations in Umudike and Otobi

Family Trial Severity scores of

parents Severity scores of

progenies 30555 97/2205 Check Lowest Highest F-value

97/2205x30555 Otobi 3 1 3.82 1 5 4.31***

N = 340 Umudike 3 1 2.76 1 4.04 2.72***

30555 96/1089A Check Lowest Highest F-value

96/1089Ax30555 Otobi 4 1 4.08 1 4 5.14*** N = 141 Umudike 2.6 1 2.5 1 4.08 1.39*

Linkage group size for SNP markers from family 97/2205 x 30555

Linkage group Number of markers

Average marker interval (cM)

Size (cM)

1 48 2.13 102.3 2 35 3.57 125.1 3 37 3.59 132.8 4 51 1.98 100.9 5 46 2.48 114.2 6 34 1.28 43.5 7 40 2.93 117.0 8 41 1.94 79.6 9 37 3.09 114.3

10 35 3.96 138.6 11 34 3.34 113.4 12 32 3.63 116.1 13 25 5.43 135.7 14 18 4.52 81.4 15 14 2.16 30.3 16 13 4.47 58.1 17 29 3.01 87.3 18 8 2.21 17.7

Total/Average* 577 3.1* 94.9*

SNP genetic linkage map of family 97/2205 x 30555

QTLs associated with resistance to CMD

Chr Position Left Marker Right Marker LOD

2 501 md076 md077 24.3743

4 1703 md168 md170 21.9322

8 636 md333 md334 18.4417

10 290 md402 md403 26.5707

13 358 md504 md506 23.5867

QTLs associated with resistance to CMD

Pyramiding of QTLs for CMD

Combining CMD2 and new QTLs to broaden resistance

Crosses derived from parents with new QTLs already being

phenotyped

ca. 100 progenies in multi-site trials for resistance to CMD

Integration of SSR and SNP maps and markers for

consensus maps/QTLs

Pyramiding of QTLs for CMD

Validating QTLs for CBSD

Populations developed and segregating for CBSD in Tanzania

Parents Number of F1 Seeds derived

Number of seedlings

established Resistant Susceptible Namikonga AR37-80 5551 621 Kiroba 3C83-13 926 334 Muzege Cheupe 657 111 B2C20-65 AR37-80 302 150 Total 7436 1216

Evaluation for the second year in Tanzania is nearing completion

Markers derived from a BMGF project to be used for validation

Frequency distribution for CBSD in 4 mapping populations

0

20

40

60

80

100

120

1 2 3 4 5

Muzege x Cheupe CBSD 6 MAP

0

20

40

60

80

100

120

1 2 3 4 5

Muzege x Cheupe CBSD 3 MAP

0

20

40

60

80

100

120

1 2 3 4 5

B2C20-65xAR 37-80 CBSD 3 MAP

0

20

40

60

80

100

120

140

1 2 3 4 5

B2C20-65 x AR 37-80 CBSD 6 MAP

0

100

200

300

400

500

600

700

1 2 3 4 5

Namikonga x AR 37-80 CBSD 3 MAP

0

100

200

300

400

500

600

1 2 3 4 5

Namikonga x AR 37-80 CBSD 6MAP

0

50

100

150

200

250

300

1 2 3 4 5

Kiroba x 3C83-13 CBSD 3 MAP

0

50

100

150

200

250

300

1 2 3 4 5

Kiroba x 3C83-13 CBSD 6 MAP

0

20

40

60

80

100

120

1 2 3 4 5

Muzege x Cheupe CBSD 9 MAP

0

20

40

60

80

100

1 2 3 4 5

B2C20-65 x AR 37-80 CBSD 9 MAP

0

100

200

300

400

500

600

1 2 3 4 5

Namikong x AR 37-80 CBSD 9 MAP

0

50

100

150

200

250

300

1 2 3 4 5

Kiroba x 3C83-13 CBSD 9 MAP

Mining for resistance gene donors in African cassava to cassava bacterial blight (CBB) and cassava green mite (CGM)

1. Leaf blighting, brownish vascular discoloration

2. Wilting

3. Die back & rapid defoliation=‘candle sticks’

1, 3 2

1 1

4 5

Cassava Bacterial Blight (CBB)

CGM

Cassava green mite (CGM) symptoms

Field evaluation for two years

Multi-site, replicated trials

Germplasm assessed for resistance to CBB and CGM

Population Type

Number of Accessions

Trait Assessed

Landraces 256 CBB, CGM Improved 183 CBB, CGM Total 439

23.0

74.2

2.7

0.0

10.0

20.0

30.0

40.0

50.0

60.0

70.0

80.0

R MS HS

Freq

uenc

y (%

)

R = Resistant; MS = Moderately susceptible; HS = Highly susceptible

21.46

52.79

25.75

0.00

10.00

20.00

30.00

40.00

50.00

60.00

R MS S

Freq

uenc

y (%

)

CBB CGM

Distribution of 256 African casssava landraces for resistance to cassava bacterial blight (CBB) and cassava green mite (CGM)

13.4

59.3

27.3

0.0

10.0

20.0

30.0

40.0

50.0

60.0

70.0

R MS HS

Freq

uenc

y (%

)

30.2

46.1

23.5

0

5

10

15

20

25

30

35

40

45

50

R MS HSFr

eque

ncy

(%)

CBB CGM

R = Resistant; MS = Moderately susceptible; HS = Highly susceptible

Distribution of 183 improved casssava genotypes for resistance to cassava bacterial blight (CBB) and cassava green mite (CGM)

NRCRI germplasm

CBB score

CGM score

IITA germplasm

CBB score

CGM score

NR/8010 1 1 188/023543 1 1 74/2 1 2 189/00748 1 1 74/640 1 2 TME-226 1 1 73/30 1 2 T983/00016 1 1 73/192 1 2 188/01226 1 1 73/404 1 2 088/00623 1 1 75/647 1 2 TME-236 1 2 75/726 1 2 TME-478 1 2 77/169 1 2 088/00378 1 2 TMX4009 1 2 087/00183 1 2

Disease and pest severity scores on the basis of 1 to 5 where 1 is no symptom and 5 is very severe symptoms

Clones identified with combined resistance to cassava bacterial blight (CBB) and cassava green mite (CGM)

New mapping populations for CMD and CBSD formed and

evaluated

QTLs for resistance to CMD identified

Pyramiding of different sources of resistance to CMD

commenced

New sources of resistance to CGM and CBB identified

Summary

Acknowledgements

NRCRI, Nigeria

Emmanuel Okogbenin

Joseph Onyeka

Others

CRI, Ghana

Elizabeth Parkes

Bright Peprah

Others

ARI, Tanzania

Geoffrey Mkamilo

Heneriko Kulembeka

Others

GCP

Xavier Delannay

Chunlin He

Others

Project Partners

Thank You!