Wheat Wide Crossing

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Wheat Wide Crossing

• Essentially 2 types
• 1. Introgression of variation from progenitors or
  species with at least one common genome
• Normal recombination on common chromosomes
• Re-synthethized (synthetic) hexaploid wheat
• 2. Crosses with more distant relatives
• No recombination with wheat chromosomes
• Aim to develop translocations
• Transmission as a single unit
• Potential problems with linkage drag
• Leymus racemosus, Rye, Agropyron/Aegilops

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Priority Pre-Breeding Targets

• Rusts
• Septoria
• Spot blotch
• FHB
• Yield potential
• Water-use efficiency
• Rainfed and irrigated systems
• Nutrient-use efficiency
• cost saving and environmental benefit
• better root systems
• Heat tolerance

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Synthetic hexaploid wheats

• Allelic variation can be recovered by going back
  to the wild ancestors of cultivated wheat
• Since the early 1990s, CIMMYT has produced over
  1100 synthetic hexaploids (850 tauschii accns)
• Aimed to increase genetic diversity especially on
  the D-genome
• Now making synthetics to introduce A B genome
  variation from wild and cultivated emmers.

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Synthetic Hexaploids

• Variation found for a large range of traits
• Rusts
• Septoria tritici
• Fusarium Head Blight
• Spot Blotch
• Drought tolerance
• Grain quality (processing)
• Grain nutritional quality
• Used in breeding at CIMMYT and distributed widely
  around the world
• Little genetic analysis initially

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Useful traits were transferred via crossing and
selection to elite CIMMYT breeding lines-
derived synthetics
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Performance of Synthetic Derived Lines in
Semi-Arid International Yield Trial (SAWYT)
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(No Transcript)
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Derived synthetics released in Spain and China (5
varieties)
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Synth-derived lines extract more water from
deeper in soil profile
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Associations among CIMMYT elite materials
genotyped with 38 SSRs
Synthetic derivatives CIMMYT breeding lines or
different ME World wide wheats
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Current focus- synthetics
How do we identify the best primaries for further
crosses?

• Direct screening for yield is difficult due to
  height and phenology
• Screening for yield, drought and heat tolerance
  or components (physiological traits).
• Association studies on SAWYT based on DARTs and
  international trial data- contribution of the D
  genome?

• Test crosses- DH or bulked F3-F4s selected for
  uniform height and flowering time Breeding value
• Haplotyping of synthetics with good disease
  resistances

• Do we need to make more synthetics?
• What variation do we need?

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Current focus- synthetics
How do we identify the best primaries for further
crosses?

• Direct screening for yield is difficult due to
  height and phenology

• Test crosses- DH or inbreds (F3-F4s?) selected
  for uniform height and flowering time ? Breeding
  value
• Multiple backgrounds

• Large effort so need to test theory on smaller
  scale first.
• Test theory with existing DHs
• Make selections of semidwarf, early flowering
  lines
• Test yield performance in different environments
• 5 populations- synthetic x Opata

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Breeding Value of Primary Synthetics
Synthetic x Opata Populations
Opata
Roelfs
Height (cm)
Syn 5
Syn 2
Syn 4
Syn 3
Syn 6
Syn 1
Flowering (days)
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Breeding Value of Primary Synthetics
Synthetic x Opata Populations
Opata
Roelfs
Yield- drought
LSD0.05 0.89
Syn 5
Syn 2
Syn 4
Syn 3
Syn 6
Syn 1
LSD0.05 1.23
Yield- full irrign
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Current focus- synthetics

• Haplotyping for FHB and STB

• FHB
• 17 fusarium resistance markers
• 71 resistant derived synthetics
• Sumai 3 QTL 3BS in 57 lines
• Wuhan QTL on 2D in 5 lines

• STB
• 15 markers for 14 of the 15 reported genes
• 2 genes are coming from Tauschii
• Stb5 from synthetic source in low of lines
• Stb8 (coming from tauschii 219 reported in the
  ITMI population) in approx 50
• An indication of the presence of novel variation
  in many primary and derived synthetics for both
  STB and FHB.

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Wheat Rye Introgressions

• Wheat and Rye have grown together for millenia
• In Afghanistan rye is Gandam dora

plant that infests barley or wheat

• Rye a common weed of wheat, cultivated later,
  further north
• First deliberate interspecific wheat crosses were
  with rye in 1870s
• Triticale
• 1BL.1RS translocation
• Natural wheat-rye introgressions

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Wheat-Rye Translocations Why Rye?

• Success of 1BL.1RS translocation
• One translocation from Petkus rye dating to 1930s
• Widespread around the world
• Yield increase and stability
• Rye is a cultivated, actively bred species
• Yield performance
• Rye and triticale have a range of superior
  attributes cf wheat
• Acid soils tolerance, drought tolerance,
  phosphorous-use efficiency
• Many introgression stocks
• Good foundation for simple, rapid introgression
  of new variation
• Good molecular tools
• Characterization tracking of introgressions

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Wheat-Rye Translocations Why Rye?

• Have 9/14 chrom arms at BC7 stage in Pavon 76
  breadwheat
• 1RL, 1RS
• 2RL, 2RS
• 3RL, 3RS
• 4RL(7DS)
• 5RS
• 6RL
• Trials last season to assess yield potential,
  drought tolerance (water-use efficiency),
  nitrogen-use efficiency, phosphorous-use
  efficiency
• Aim for all rye chromosome arms as single
  translocations
• Smaller segments a longer term aim

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Rapid introgression and evaluation
Elite wheat translocation
Rye
X
Select chrom number, presence of 3RS, recomb on
3RS
20, 3DL.3RS
1R-7R
F1 x
Recomb 3RS
Self
20, 3DL.3RS (recomb)
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Field trials
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Leaf Rust Reaction of Pavon-Rye Translocation
lines (BC7 inbreds)
Sus
Res
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Yield of Pavon-Rye Translocation lines (BC7
inbreds)
LSD0.05 0.73
Yield- drought
LSD0.05 0.91
Yield- full irrign
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Natural Rye Introgressions

• Wheat and rye in mixed stands for millenia
• Rye a weed of wheat, cultivated later, further
  north
• Accounts of Vavilov
• Barbela landrace- deliberate mixture
• Multiple small interstitial introgressions (ISH)
• Present in other Landraces?
• Small introgression segments
• Greater opportunity to identify with more precise
  molecular tools
• Dispersed repeated element
• High density maps (SSRs, SNPs)
• Genomic sequencing

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Natural Rye Introgressions

• Barbela wheat landrace with rye insertions

• 2DL2R
• From Ribeiro-Carvalho et al 2001

• 2DS.2DL.2RL(5) (Ribeiro-Carvalho et al 2001)
• 5DS small rye terminal insert (Silva et al
  1996)
• Unknown with small terminal insert
  (Ribeiro-Carvalho et al 2001)
• Unknown with terminal and intercalary rye
  segments (Ribeiro-Carvalho et al 2001)

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Natural Rye Introgressions

• Barbela wheat landrace with rye insertions

• Only small amount of the available Barbela
  collection sampled
• Good chance of finding small segments on other
  chromosomes in Barbela and other landraces
• Better molecular tools available
• Screening of Barbela and other landraces an
  important focus of future rye activities

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Nitrogen-Use Efficiency from Leymus racemosus
Other NUE mechanisms?
Plant uptake N2O Pollution
(greenhouse gas)
NH4 NO2- NO3- Non-mobile Highly
mobile in soil in soil
BNI (Biolocical nitrification inhibition)
Nitrosomonas europaea (Ammonia-oxidizing bacterium
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NUE from L. racemosus
Stock racemosus chromosome racemosus chromosome Homol gp in wheat BNIa DW/plant NH4 tolb
L. racemosus 31.55 3.61 T
Chinese Spring 6.39 4.52 S
DALrn Lrn 3 and 7 24.57 3.15 S
DALrJ LrJ 7 13.47 2.66 S
DALrI LrI 5 13.02 2.07 S
DALrl Lrl 2 6.4 2.15 S
DALrk Lrk 6 5.5 2.75 S
DALrF LrF 4 4.12 1.84 S
DALrH LrH 3 3.65 2.24 S
DA2Lr1 2Lr1 2 3.16 2.04 S
DA5Lr1 5Lr1 5 6.55 2.72 S
DtA7Lr1-1 7Lr1-1 7 6.38 3.38 T
DtA7Lr1-2 7Lr1-2 7 4.9 1.64 S
DA disomic addition, Dt ditelosomic addition of
L. racemosus chromosomes to/with Chinese Spring
chromosomes. a Root exudate collected using 1 mM
NH4Cl. b Tolerance score based on the appearance
of chlorosis symptoms, where chlorosis was
considered as a sign of sensitivity
to assimilation of N in NHþ 4 form.
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L. racemosus ongoing activities

• Field trials in Chinese Spring background
• Confirm BNI in field
• Compare yield performance under low and high N
• Nutrient-use efficiency (NP)
• Backcrossing into better backgrounds
• Generating new translocations (some in Pavon
  background)

• Markers
• Define break point, retain key wheat alleles
• High-throughput marker for breeding

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• Thankyou