head scab update

Head Scab Update

Dave Van SanfordUniversity of Kentucky

US Wheat & Barley Scab Initiative

Head Scab

Fusarium graminearum

Corn stubbleCrop debris

Perithecia

ascosporesmacroconidia

Effects of Head Scab

• Reduced Yield• Reduced Test Weight• Reduced Grain Quality• Mycotoxin(s)

What is Deoxynivalenol (DON)?

• Tricothecene• Thermally stable• Chemically stable• Causes vomiting,

weight loss, feed refusal in livestock

• Can affect bone marrow, lymphoid tissues, immune system

Deoxynivalenol (DON). 2 ppm threshold for milling.5 - 10 ppm threshold for feed.

“One tombstone in 150 grains gives a value of 2 ppm”

Mounting a Campaign against Head Scab

• Epidemics in early 1990’s– 1993 loss of $ 1 Billion in North Dakota

• 1996 epidemic in northern corn belt - millers could not find low DON grain

• Went to Congress, secured Emerging Diseases funds

• 1997 - USWBSI formed

US Wheat and Barley Scab Initiative

• Co-chairs: Farmer and Researcher• Executive Committee: 9 members

including breeders, pathologists, miller rep, malting/brewing rep

• Steering Committee: Broad based includes stakeholders (growers, millers, seed industry, chemical industry, malting/brewing, pasta) Ag. Admin. and scientists

US Wheat and Barley Scab Initiative

• Research Area Committees– Variety Development/Uniform Nurseries– Chemical/Biological Control– Epidemiology– Host plant genomics– Host plant genetic resources– Transformation– Pathogen genomics– Food Safety

Progress?

• From FY99-FY06 the USWBSI spent $36,917,338

• What have we accomplished?

Accomplishments

• Varieties– Sumai 3 derived: Alsen, Steele,25R18, others– Native resistance: Truman, Bess– Many others in the pipeline– Uniform nurseries have identified resistant

lines– Many resistant parents developed– Reduction in VS varieties

Major QTL and markers used for FHB resistance in wheat

Name    Location QTL Donor Marker(s) References

Qfhs.ndsu-3B    3BS Sumai 3 barc133, Xgwm493, Xgwm533

Anderson et al. (2001)

Qfhs.ifa-5A     5AS Sumai 3, Wuhan 3

barc180, barc186 

Buerstmayr et al. (2002);McGowan (2002), Somers et al. (2003)

Qfhs.ndsu-3AS   3AS T.dicoccoides         

Xgwm2, Otto et al. (2002)

3AL Frontana Xdupw227, Xgwm129

Steiner et al. (2004)

Combining Sumai 3 and T. dicoccides: Release of Glenn and ND 744 Germplasm

X Steele-ND

Glupro

Amidon

2*/Grandin

/5/Parshall= KEENE/ND674

IAS20*4/H567.71 X RL4352-1 X T.dicoccoides

//LEN/3/Grandin

X Grandin*2/'Glupro'

Grandin' (PI 531005)/3/IAS20*4/H567.71

//'Amidon'

ND2831 'Sumai 3'/'Wheaton'//'Grandin'/3/ND 688

ND 747=GlennND744

Accomplishments

• Uniform Fungicide Trials– Have provided data that allowed 6 states to

secure Section 18 for Folicur (IL, KY, MI, MN, ND, SD)

– Have demonstrated that the problem with the strobiluron fungicides increasing DON concentration in the grain was real

Accomplishments

Recent Events

• 2003 SRW epidemic - good looking wheat

with high DON - millers’ nightmare

• 2004 epidemic in southern corn belt

• 2005 ND/MN epidemic - $200 M in losses,

mostly due to DON discounts

Tom Anderson, Co-Chair: We haven’t made enough progress

Recent Events : The Increasing Importance of DON

• 1993 ND crop - most losses at farm gate due to reduced yield, test weight

• 2005 ND crop - most losses due to DON discounts

• The market wants low DON wheat!• July 1 2006: European DON standards -

1.25 ppm in imported grain

Recent Events: The Millers’ Challenge

• Lower DON by 50% in three years

• OR ELSE!

What Is Our Game Plan?

• Beyond our RAC structure - we didn’t have one

• Decided to write an ACTION PLAN

The 2006 Scab Forum

• 2. 5 days of breakout sessions and brainstorming

• Lots of stakeholders involved• Underscored to scientists the need to work

in partnership with industry

Outcomes

• Key Research Needs– Database/Info sharing: not a good mechanism

in place to make this happen– Communication: among scientists, from

scientists to stakeholders– Collaboration/Integration: pathologists are way

ahead of breeders in this respect

• Integrated Management Studies– Varieties, + fungicides, different residues

Research Needs - Variety Development Group

• Information to determine whether “new” sources of resistance are truly “novel” sources of resistance – marker haplotyping, allelism testing etc.

• Coordination to strategically distribute new sources to different breeding programs for crossing and first generation “pre-breeding”.

• Sharing of pre-breeding populations.• Enhanced phenotyping of mapping

populations (more environments in fewer years).

Research Needs - Plant Pathologists

• Develop “ScabSmart” platform for info exchange

• Industy-University alliance to interpret good farming practices

• Conduct region-wide training events for growers, consultants and ag agents

• Get the word out!

Seed Companies - the dilemma

• Farmers have short memories - they want to plant the next hot thing

• Seed companies must make a profit to stay in business

• Some companies offer racehorse varieties with no scab resistance

Markets - the dilemma

• Must be a market signal that tells the growers to plant scab resistant wheat

• Millers say that scab resistance is their No. 1 quality trait

• Farmers say “well then, pay for it”.• Some farmers report that the market does

pay a premium for low DON wheat in epidemic years (eg. MN in 2005)

Scabtalk Website

• Invited scab community to post anonymous comments

• Provide feedback on the direction of the Initiative

Commentary

“The Initiative has been too near-sighted and afraid to recognize the fact that current breeding efforts are unable to control scab epidemics. More basic work is needed to understand the host-pathogen interxn, particularly at molecular and biochemical level. Only when we know the key steps of this interaction can we draw an effective strategy to deal with this disease.”

Commentary

“Let’s be realistic, is has taken a decade just to find out what germplasm is available to use as a resistance source and breeders have barely begun to pyramid these sources. I truly

believe that in 5-10 years there will be enough moderately resistant varieties available to satisfy grower needs and preferences.”

It Is Time to Apply What We Have Learned So Far

“ Although there are many questions to answer,there is

a good base of knowledge that is not being applied to

its full potential. There is a strong need for

multidisciplinary projects that will integrate knowledge

from different disciplines. Although knowledge-driven

projects are more appealing to university scientists,

the knowledge-application projects are the ones that

will deliver the goods to the farmers.”

Action Plan/ Reorganization

• Make no changes• Top Down Model• “CAP Grant” Model• Uniform Nursery Centered

Uniform Nursery Model

• Uniform nursery grown as now; haplotyped at Genotyping Lab

• Pathologists screen nursery under fungicide• Make data available on web• All cooperators evaluate varieties in their

states for scab resistance; available on web• Joint phenotyping of mapping populations• Info maintained in shared database• Organize and facilitate pre-breeding;

genotyping lab would screen pops

What about…

• High risk approaches?

• Transgenic wheat?

A Breeding Solution?

• Under severe epidemic conditions, the Sumai 3 resistance (or Sumai 3 plus diccocoides (cv Glenn)) is not enough

• It is possible to find excellent native resistance in some market classes (eg. Truman SRW)

• What about the combination of these sources? We don’t know.

• What about the best resistance plus a fungicide? We don’t know.

The Future

• Very likely to involve team - based integrated problem solving approaches

What Will It Take?

• The best genetic resistance we can find, introgress and maintain

• Use of fungicides to prevent/slow epidemic development in heavy FHB env.

• Cultural control practices to either mitigate disease problems from infested residue and to make the environment less favorable for inoculum or disease development

• Something like a forecasting system to tie in the management of all of these pieces.