Progress on breeding for

drought and heat tolerance in

maize

J Cairns, JL Araus, C Sanchez, S Trachsel, R Babu, J Crossa, S

Hearne, D Makumbi, S Taitad, C Magorokosho, A Menkir,

M Banziger, C Bedoya, PH Zaidi

Overview

● Progress in breeding for heat and drought tolerance

● Genetic analysis of grain yield under drought and

heat stress

● Effects of 1-MCP on stay green and grain yield under

drought

● Outlook on CIMMYTs current activities for heat

screening

Susceptibility to heat stress

Lobell et al. 2011

Increase in maximum temperatures (2050)

Thornton et al. 2009

Kai Sonder/Cairns et al. 2012

Anthesis-silking interval (d)

Gra

in y

ield

(t

ha

-1)

Combined drought and heat stress

Anthesis-silking interval (d)

Gra

in y

ield

(t

ha

-1)

Drought stress

Drought ≠ Drought + heat

Sensitivity of maize to high temperatures

Reduced

pollen shed

Reduced pollen

viability

Sensitivity of maize to high temperatures

Anthesis-silking interval (d)

Gra

in y

ield

(t

ha

-1)

Fonseca and Westgate, 2005

Pollen shed duration

Pollen quality

(shed & duration)

Zimbabwe,

2011

Chiredzi, Zimbabwe 2011

Sensitivity of maize to high temperatures

Fre

qu

en

cy

SPAD (2 weeks after anthesis)

Heat + drought

Drought

Relationship between combined drought

and heat stress

Drought

Drought + Heat Heat

Well-watered

Drought -

Drought + heat

0.08 -

Heat 0.49 -0.07 -

Well-watered 0.63 0.24 0.27 -Cairns et al. 2012 submitted

Phenotyping GermplasmManagement

options

Future opportunities

Semi-

controlled

(FATE)

Field

Tools

Current

breeding

pipeline

Heat

breeding

Germplasm

movement

Conservation

agriculture

Seed

production

options

Growth

regulators

Identification of heat tolerant donors

Phenotyping of the Drought Tolerant Maize for Africa

(DTMA) association mapping set

Phenotyping in 5 countries across 3 years

Drought, heat, combined drought and heat stress, well-watered

Evaluation of DTMA germplasm under

abiotic stress

Test environment

No. of trials Grain yield

(t ha-1) VG VGE VE H

Optimal 7 6.88 0.35 0.24 0.48 0.84

Managed drought 7 2.58 0.12 0.36 0.39 0.64

Managed drought + heat 3 1.13 0.07 0.12 0.18 0.50

Effect of heat stress on grain yield

Year 2010 2011

TemperatureOptimal T High T Optimal T High T

Supra-High

T

GY, WW (t ha-1)* 7.39 6.45 7.38 6.27 1.50

GY, DS (t ha-1) * 3.29 0.24 2.67 2.25 -

LPSC7F64-2-6-2-2/CML312SR* 3.70 1.24 2.72 3.12 1.85

CML444/CML312* 3.88 0.19 2.50 2.38 -

ASI (DS) 2.1 12.0 2.9 2.6

-

LSD (5%) 0.90 0.51 1.36 1.12 1.23

H 0.69 0.32 0.80 0.72 0.64

*Adjusted means (BLUPS)

- 12% - 15% - 80%

Effect of heat stress on grain yield

Year 2010 2011

TemperatureOptimal T High T Optimal T High T

Supra-High

T

GY, WW (t ha-1)* 7.39 6.45 7.38 6.27 1.50

GY, DS (t ha-1) * 3.29 0.24 2.67 2.25 -

LPSC7F64-2-6-2-2/CML312SR* 3.70 1.24 2.72 3.12 1.85

CML444/CML312* 3.88 0.19 2.50 2.38 -

ASI (DS) 2.1 12.0 2.9 2.6

-

LSD (5%) 0.90 0.51 1.36 1.12 1.23

H 0.69 0.32 0.80 0.72 0.64

*Adjusted means (BLUPS)-

55%

-63%

Effect of heat stress on grain yield

Year 2010 2011

TemperatureOptimal T High T Optimal T High T

Supra-High

T

GY, WW (t ha-1)* 7.39 6.45 7.38 6.27 1.50

GY, DS (t ha-1) * 3.29 0.24 2.67 2.25 -

LPSC7F64-2-6-2-2/CML312SR* 3.70 1.24 2.72 3.12 1.85

CML444/CML312* 3.88 0.19 2.50 2.38 -

ASI (DS) 2.1 12.0 2.9 2.6

-

LSD (5%) 0.90 0.51 1.36 1.12 1.23

H 0.69 0.32 0.80 0.72 0.64

*Adjusted means (BLUPS)

Effect of heat stress on grain yield

Year 2010 2011

TemperatureOptimal T High T Optimal T High T

Supra-High

T

GY, WW (t ha-1)* 7.39 6.45 7.38 6.27 1.50

GY, DS (t ha-1) * 3.29 0.24 2.67 2.25 -

LPSC7F64-2-6-2-2/CML312SR* 3.70 1.24 2.72 3.12 1.85

CML444/CML312* 3.88 0.19 2.50 2.38 -

ASI (DS) 2.1 12.0 2.9 2.6

-

LSD (5%) 0.90 0.51 1.36 1.12 1.23

H 0.69 0.32 0.80 0.72 0.64

*Adjusted means (BLUPS)

Grain yield (t h-1)* Grain yield (rank)#

Rank Pedigree Drought

Well-

watered

Drought +

heat Heat

1 DTPYC9-F46-1-2-1-2 2.66 7.35 2 130

2 La Posta Seq C7-F86-3-1-1-1 2.53 7.46 155 142

3 CL-G1628=G16BNSeqC0F118-1-1-4-2 2.53 7.08 16 111

4 La Posta Seq C7-F64-2-6-2-2 2.51 7.88 3 13

5 La Posta Seq C7-F78-2-1-1-1 2.51 7.79 184 270

6 DTPWC9-F24-4-3-1 2.49 7.27 15 62

7 La Posta Seq C7-F180-3-1-1-1 2.48 7.76 113 229

8 DTPYC9-F46-1-2-1-1 2.48 7.14 17 114

9 La Posta Seq C7-F103-2-2-2-1 2.45 7.76 179 10

10 [CML-384 X CML-176]F3-135-2-2-1 2.45 7.98 283 272

*Adjusted means (BLUPS)#300 entries within trial

Ensuring drought tolerant germplasm

for future environments

Identification of heat tolerant donors

Pedigree GY (t ha-1)

CML311/MBR C3 Bc F12-2-2-2 0.63

DTPYC9-F46-1-2-1-2 0.59

La Posta Seq C7-F64-2-6-2-2 0.55

CLA44 0.49

DTPYC9-F143-5-4-1-2 0.46

CML412 (check) 0.19

Trial mean 0.24

Combined heat and

drought tolerance

Heat stress tolerance

Pedigree GY (t ha-1)

DTPWC9-F67-2-2-1 2.60

CML497=[CL-00331*v]-3-B-3-2-1 2.59

La Posta Seq C7-F10-3-3-1-1 2.57

DTPYC9-F114-2-4-1-2 2.45

1368 2.42

Trial mean 1.50

Drought donors (with heat tolerance)

http://dtma.cimmyt.org/index.php/varieties/dt-donors

Cluster AnalysisD

ista

nce

Well-wateredDroughtDrought+heatHeat

PC

2 (2

1.4

%)

PC1 (34.9 %)

Well-wateredDroughtDrought+heatHeat

PCA for genetic correlations matrix

Structure in DTMA-AM panel

PC Eigenvalue

1 9.52

2 8.96

3 6.62

4 4.74

5 3.61

6 3.22

7 3.05

8 2.90

9 2.76

10 2.64

� PCA analysis based on 55K SNPs

� No pronounced structure in the DTMA-AM panel – first 10 PCs explain ~ 50% of the variation

DTMA-AM panel and 55K SNPs can identify large effect genes – 1. Grain Color

Psy2R² = 14%

Psy1R² = 37%

SNP with largest significant association with grain color located within one of the exons of Phytoene Synthase1 (psy1) on chr.6

92 – Yellow lines (1)186 – white lines (0)

DTMA-AM panel and 55K SNPs can identify large effect genes – 2. QPM

Opaque2 at 7.01R² = 16%

Ask2?R² = 8%

Besides opaque-2 and ask-2, several minor QTL regio ns influencing kernel modification and tryptophan cont ent identified that overlap with previously reported re gions…

10 – QPM lines (1)268 – Normal lines (0)

Haplotype based association analysis for GY under stress (drought)

7.3%6.2%5.7%

7.0%

5.7%5.5%

5.1%

5.8%

4.9%

5.1%

• 50K SNPs were reduced to 10K haplotype blocks and association test was performed correcting for population structure using principal components and results validated with mixed linear model analysis (kinship + structure)

• Only 47 SNPs (~15 genomic regions) out of 10,000 had R2 values more than 5%Raman Babu

Haplotype based association analysis for GY under combined drought + heat

• Noise levels are relatively higher under very severe stress condition• Significant regions such as those on chr.10, chr.9, chr.4 and chr.7 also

got identified in the severe stress condition… Raman Babu

Plant growth regulators -2010 (recap)

Drought stress (DS)Well-watered (WW)

Summary of experimentGenotypes: 1 (DTPYC9-F74-1-1-1-1)Water treatments: well-watered and drought stressChemical Treatments: control (water), 1-MCP (single dose of 10 g ai ha-1 and double dose 20 g ai ha-1), ethephon (single dose of 1.5 l ha-1 and double dose of 3 l ha-1)Application time: 1 week before anthesis or 10 days after anthesis

Results1) No significant differences between control and chemical treatments under WW conditions2) Drought stress reduced grain yield by ~76 % relative to WW control3) Yields under DS were significantly higher with a single dose of 1-MCP applied prior to and

after anthesis, and a double dose Ethephon applied after anthesis

Plant growth regulators -2011

Summary of experimentGenotypes: 6; Water treatments: 2 (well-watered and drought stress); Chemical treatments: 9Sowing date: 14th Feb 2011

Entry

Genotype

1 DTPYC9-F74-1-1-1-1/CML-451

2 LPSC7-64-2-6-2-2/CML-495

3 2A120 (Dow)

4 (CML-269/CML-264)//CML-494

5 CML-442/CML-444

6 DTPYC9-F66-2-1-1-2/ CML-539

Treatment Chemical Dose Timing

1 Control - Before anthesis

2 Control - After anthesis

3 1-MCP Singlea Before anthesis

4 1-MCP Doubleb Before anthesis

5 1-MCP Single After anthesis

6 1-MCP Double After anthesis

7 Ethephon Singlec Before anthesis

8 Ethephon Doubled Before anthesis

9 Ethephon Single After anthesis

Genotypes Chemical treatments

a10 g ai ha-1

b20 g ai ha-1

Plant growth regulators - 2011

DTPYC9-F74-1-1-1-1/CML-451 LPSC7-64-2-6-2-2/CML-495

2A120 (Dow) (CML-269/CML-264)//CML-494

Treatments1: Control (before anthesis); 2: control (after anthesis); 3: 1-MCP (single app, before anthesis); 4: 1-MCP (double app, before anthesis); 5: 1-MCP (single app, after anthesis); 6: 1-MCP (double app, after anthesis_; 7: Ethephon (single app, before anthesis); 8: Ethephon (double app, before anthesis); 9: Ethephon (single app, after anthesis)

TreatmentTreatment

Gra

in y

ield

(t h

a-1 )

Gra

in y

ield

(t h

a-1 )

WW

DS

Plant growth regulators - 2011

WW

DS

CML-442/CML-444 DTPYC9-F66-2-1-1-2/ CML-539

Treatment

Gra

in y

ield

(t h

a-1 )

Treatment

Results1) Drought stress reduced grain yield by 60% relative to the WW control2) No significant differences in grain yield between chemical treatments under WW and DS

conditions3) No significant difference in the % reduction in GY relative to the WW control between

chemical treatments

Plant growth regulators - 2011

Treatment Treatment

ND

VI

18 days after anthesis 25 days after anthesis

Results1) Under drought stress 1-MCP delayed senescence (estimated through NDVI) 18 and 25

days relative to the control (p<0.01)2) There was no significant genotype*treatment interaction3) No significant difference in NDVI was identified 32 days after anthesis

Treatments1: Control (before anthesis); 2: control (after anthesis); 3: 1-MCP (single app, before anthesis); 4: 1-MCP (double app, before anthesis); 5: 1-MCP (single app, after anthesis); 6: 1-MCP (double app, after anthesis_; 7: Ethephon (single app, before anthesis); 8: Ethephon (double app, before anthesis); 9: Ethephon (single app, after anthesis)

Can landraces help improved tolerance to

drought and high temperatures?

Evaluation of landraces under WW and DS

Status

Cluster analysis for 38 Mexican

populations

Use of accesions in breeding

Summary- Different Mechanisms allow plants to cope with

drought, high temperatures - Accordingly there is only little overlap between

germplasm tolerant to the three stresses- In several years of screening under drought, high

temperatures CIMMYT has identified hybrids and crosses that are tolerant to these stresses

- Tolerant lines are available for partners to be used in their breeding pipeline.

- CIMMYT keeps screening germplasm for tolerance to heat in Ciudad Obregon and potentially in Arizona

- Attempts are underway to identify alleles conveying tolerance to abiotic stress in landraces