GRM 2011: Development and evaluation of drought-adapted sorghum germplasm for Africa and Australia

Working together with the Queensland Government

Developing drought-adapted sorghum

germplasm for Africa and Australia

University of

Queensland

Andrew Borrell David Jordan

Queensland

Government

Barb George-Jaeggli

IER, Mali

Sidi Bekaye Coulibaly

Niaba Teme

Mamoutou Kouressy

CIRAD, Mali

Michel Vaksmann


Outline

1. The „stay-green‟ trait

2. Overview of GCP project

3. Physiological studies in Australia

4. Stay-green germplasm for Mali

5. Conclusions


Maintaining green

leaves and stems when

water is limiting during

the grain-filling period

1. The “stay-green” trait

Stay-green Senescent


Crop productivity in water-limited environments is

regulated by:

Drought adaptation

Stay-green affects all three processes.

a) the extent of water capture by the crop (T),

b) the efficiency with which the crop

exchanges water for CO2 via transpiration in

producing biomass (TE), and

c) the fraction of the total biomass that ends up

in the grain (HI).


Higher yield

Increased water use during grain filling

Increased water availability at flowering

Increased water

accessibility

(roots)

Reduced water

use at flowering

Higher plant

water status

Increased

growth rate

Increased

TE

Delayed leaf

senescence

Smaller

plant size

„Low tillering‟

mechanism

„Small leaf‟

mechanism

Modified leaf

anatomy

Driving T

Driving TE

Driving HI

Emergent

consequences

Increased N

uptake

Increased

stem strength


2. Overview of GCP project

Development and evaluation of drought-

adapted sorghum for Africa and Australia


African partners (Phase 1)

Mali

Institut d‟Economie Rurale (IER)

CIRAD, Bamako, Mali


African partners (Phase 2)

Niger, Sudan, Ethiopia,

Kenya & Uganda


Objective 1. Determine the impact of changes

in plant height and photoperiod sensitivity

on the expression and value of stay-green

Objective 2. Develop Malian germplasm

enriched for stay-green QTLs

Objective 3. Training of African scientist(s) in

the physiology and breeding of drought

adaptation

Objectives (Phase 1)


Objectives (Phase 2)

Objective 1: Evaluating in Africa the material

produced in Phase 1

Objective 2

• Training in Australia for visiting African

scientists on sorghum crop improvement

• Training in Africa by visiting Australian

scientists on sorghum crop improvement

Objective 3: Evaluation of African germplasm for

known stay-green regions


Knowledge gaps

Interaction between stay-green and plant height is

unknown.

Interaction with photoperiod response is unknown.

Value of the trait will be influenced by the types of

drought experienced in Mali.

Will stay-green be useful in

Mali ?

Challenges

Value of stay-green is more obvious in hybrids

compared with inbred lines.

Variation in flowering time complicates conventional

selection.

Selecting for stay-green while retaining local

adaptation (PPS, grain quality, pest resistance etc).


3. Physiological studies in Australia


Creating „managed‟ environments

Irrigated Control

(HD & LD)

Water-Limited Treatment

(HD & LD)

Low density

(mild drought)

High density

(severe drought)


Genotypes

Tall & stay-green

(R931945-2-2)

Short & stay-

green

(R931945-2-2)

Tall & senescent

(R955343-1)

Short &

senescent

(R955343-1)


Seasonal variation

2009: Post-flowering drought

(stopped irrigating 2 weeks

before flowering)

2010: Pre-flowering

drought (stopped

irrigating 3 weeks

before flowering)

2011: Post-flowering

drought (stopped

irrigating 3 weeks

before flowering)


Retention of green leaf area

0

5000

10000

15000

20000

25000

Gre

en leaf are

a

(cm

2/m

2)

T S T S T S T S

R931945-2-2

(stay-green)

R955343-1

(senescent)

R931945-2-2

(stay-green)

R955343-1

(senescent)

High Low

2009

The stay-green pair retained more green leaf area at maturity than the senescent pair

under both high and low density treatments. There were no significant differences in

green leaf area between tall (T) and short (S) isolines of the stay-green pair.


Grain yield

0100200300400500600700800

Gra

in y

ield

(g/m

2)

T S T S T S T S

R931945-2-2

(stay-green)

R955343-1

(senescent)

R931945-2-2

(stay-green)

R955343-1

(senescent)

High Low

2009

The stay-green pair exhibited higher grain yield than the senescent pair under both high

and low density treatments. Grain yield was higher in the tall (T) than short (S) isoline of

the stay-green pair under both densities. Hence, the „tall stay-green‟ combination yielded

particularly well under post-flowering drought.


Lodging resistance

-200

-150

-100

-50

0

50

100

Delta s

tem

mass (

g/m

2)

T S T S T S T S

R931945-2-2

(stay-green)

R955343-1

(senescent)

R931945-2-2

(stay-green)

R955343-1

(senescent)

High Low

2009

Under stressed conditions, the stay-green pair remobilized less stem reserves during grain filling than

the senescent pair under both high and low densities. Less stem reserves were mobilized in the tall (T)

than short (S) isolines in the stay-green pair, while the reverse was true for the senescent pair. This

suggests that stay-green should provide much-needed lodging resistance in tall sorghums under post-

flowering drought.


Stay-green

Senescent

0

50

100

150

200

250

300

350

16 30 44 65 73 79 86 93 100 107 121 137

Cu

mu

lati

ve w

ate

r use

(m

m)

Days after emergence

Low Density (2011)


4. Germplasm with enhanced stay-green

and adaptation for Mali

The DEEDI sorghum breeding program has been

selecting for the stay-green trait in sorghum for more than

30 years while simultaneously selecting for grain yield.

In Australia, 3-dwarf hybrids with stay-green have been

shown to increase grain yield & grain size, and decrease

lodging in crops subjected to post flowering drought.

Choosing a stay-green donor

• Options: B35 or an elite line from the DEEDI program

• Chose R931945-2-2 as a well characterized line from

the DEEDI program with high SG and good yield potential

and other potentially useful traits (e.g. midge resistance).

Stay-green Senescent

R2 = 0.218

0

1

2

3

4

5

6

7

8

2 3 4 5 6 7 8 9

Stay-green rating (1=SG 9=dead)

Yie

ld t

/ha

Data from 20 breeding trials (934 hybrids)

conducted between 2005 and 2008


Produce populations based on elite

material from Mali (Phase 1)

Prior to the commencement of the GCP project, DEEDI

had developed 33 F2 populations each based on a cross

between a diverse set of germplasm lines from Mali with

the elite DEEDI line (R931945-2-2).

In consultation with Malian breeders, four of the 33

populations were chosen for:

• backcrossing to the recurrent parent and

selection for four SG QTL;

• development of RIL populations; and

• production of F1 hybrids with CMS lines

contrasting in SG.


Evaluation in Africa of material

produced in Phase I (Phase 2)

Seed from selected BC1F2 will be used by Malian

collaborators for final stage selection and evaluation.

QTL-enriched lines will be evaluated in about 12 trials per

year (6 countries x 2 sites per country) over 2 years.

Target countries will include Mali, Niger, Sudan,

Ethiopia, Kenya and Uganda.

Five plants from each of 15 backcross-derived

introgression lines have been selected (13 lines from

F2_R04021-2/PI609084 and 2 lines from F2_R04003-

2/PI585749).

Hence about 75 genotypes x 2 reps x 2 water regimes

(WW & WD) will be evaluated per site, depending on

irrigation capacity for WW treatment.

Evaluation will focus on yield, height, maturity, stay-

green and grain quality.


Evaluation of African germplasm for

known stay-green QTL (Phase 2)

Four RIL populations containing between 170 and 400 lines (totaling 917

individuals) will be phenotyped at the F4 generation (2012). Lines were selected for

height and PPS similar to the recurrent parent. QTL mapping studies will be

conducted in Phase 2.

Seed of 6 F1 hybrids produced. Trials will be conducted to compare the yield and

stay-green of the F1 hybrids at 2 sites in Mali during 2012.


Variables & constants are

initialised in model or read

from spreadsheet (can

also read APSIM met files

etc to prototype)

Variables & constants are

initialised in model or read

from spreadsheet (can

also read APSIM met files

etc to prototype)

Can compare runs &

monitor all variables using

graph tools (or via APSIM

tools, with VenLink)

Can compare runs &

monitor all variables using

graph tools (or via APSIM

tools, with VenLink)

At present, VenLink to

APSIM is only for complete

modules, but Dean

Holzworth is going to

enable Vensim to work as

a sub-module, e.g. crop

process

At present, VenLink to

APSIM is only for complete

modules, but Dean

Holzworth is going to

enable Vensim to work as

a sub-module, e.g. crop

process

Great tool for prototyping

ideas before programming

APSIM module

Great tool for prototyping

ideas before programming

APSIM module

Genomics Simulation Modelling

Data management

Phenotypic data

Integrated

information that is

better able to

address complex

quantitative traits

Environmental

characterisation

Enhanced genetic gain

Training on linking breeding,

molecular & physiological aspects


Cost-effective HTP whole

genome profiling technology

Applied to QTL and association

mapping studies

Genomics: What do you need?

Good quality genetic linkage maps

Applied to structured and

unstructured germplasm sets

Knowledge of genomic regions controlling

key traits

Put this is context of existing knowledge of

other QTL and major effects genes in order

to develop more effective breeding

strategies


Stg1


Stg1 QTL region

67 markers across

376 genotypes (AYT)

With such dense marker data sets, we

can look at the haplotypes in selected

QTL regions. This example focuses on

Stg1 on SBI-03. We can identify which

haplotype class is derived from stay-

green lines vs those from senescent lines.

B35 derived

haplotype

(stay-green)

Principal component analysis


5. Conclusions (Physiology)

1) Height did not counteract the benefits of stay-green. On

the contrary, under stress, the tall version of the stay-

green pair yielded significantly more than the short

version.

2) The yield advantage in the tall version of the stay-green

pair was due primarily to larger grain size.

3) Stem mass during grain filling increased in the stay-

green pair and decreased in the senescent pair,

highlighting the role of stay-green in lodging resistance,

particularly in the tall version of the stay-green pair.

4) Tall stay-green line extracted more water during grain

filling than the tall senescent line.


Conclusions

(Population development)

1) About 75 QTL-enriched lines will be evaluated in 12

trials per year (6 countries x 2 sites per country) over 2

years.

2) Four RIL populations containing between 170 and 400

lines (totaling 917 individuals) will be phenotyped at the

F4 generation.

3) Yield and stay-green of six F1 hybrids will be compared

at 2 sites in Mali.


Conclusions (Training)

1) Intensive training for two Malian

scientists in Australia on physiological

methods and breeding techniques

related to drought adaptation will occur

in Feb 2012 (Phase 1).

2) Workshop in Africa on „breeding for

drought‟ and „physiology of drought

adaptation (Phase 2).

3) Six African scientists will work with the

sorghum program in Australia for 3

months each (Phase 2).




Canopy development

0.00

0.20

0.40

0.60

0.80

1.00

1.20

Tille

rs/p

lant

Tall Short Tall Short

R931945-2-2 (stay-green) R955343-1 (senescent)

2009

The stay-green pair reduced tillering compared with the senescent pair. There were no

significant differences in tillering between tall (T) and short (S) isolines of the stay-green

pair.


Implications for the grains

industry


Stay-green

Senescent

0

50

100

150

200

250

300

350

16 30 44 65 73 79 86 93 100 107 121 137

Cu

mu

lati

ve w

ate

r use

(m

m)


High Density (2011)

Stay-green

Senescent

0

50

100

150

200

250

300

350

16 30 44 65 73 79 86 93 100 107 121 137

Cu

mu

lati

ve w

ate

r use

(m

m)


Low Density (2011)


Leaf senescence

0

10

20

30

40

50

60

SP

AD

(F

L-2

)

T S T S T S T S

R931945-2-2

(stay-green)

R955343-1

(senescent)

R931945-2-2

(stay-green)

R955343-1

(senescent)

High Low

2009

The stay-green pair retained greener leaves (higher SPAD) during late grain filling than

the senescent pair under both high and low density treatments. There were no significant

differences in leaf greenness between tall (T) and short (S) isolines of the stay-green pair.


Stay-green

Senescent

0

50

100

150

200

250

300

350

16 30 44 65 73 79 86 93 100 107 121 137

Cu

mu

lati

ve w

ate

r use

(m

m)


High Density (2011)


Grain size

0

5

10

15

20

25

30

Grain

mass (

mg)

T S T S T S T S

R931945-2-2

(stay-green)

R955343-1

(senescent)

R931945-2-2

(stay-green)

R955343-1

(senescent)

High Low

2009

Under stressed conditions, the stay-green pair exhibited larger grain size than the

senescent pair, particularly under low density. Grain size was generally larger in the tall (T)

compared with the short (S) isolines of the stay-green pair.

Technology

GRM 2011: Development and evaluation of drought-adapted sorghum germplasm for Africa and Australia