Technology: What is in the Sorghum Pipeline

Zhanguo Xin Gloria Burow Chad Hayes Yves Emendack

Lan Liu-Gitz, Halee Hughes, Jacob Sanchez, DeeDee Laumbach, Matt Nesbitt

ENVIRONMENTAL CHALLENGES REDUCE YIELDS AT EVERY STAGE OF DEVELOPMENT

Data Items 2011 2010

SORGHUM - ACRES PLANTED 5,451,000 5,369,000

SORGHUM, GRAIN - ACRES HARVESTED 3,945,000 4,806,000

SORGHUM, GRAIN - YIELD, BU / ACRE 54 71.9

Source: NASS

Germplasm Evaluation:Drought Tolerance:

Pre-Flowering TolerancePost-Flowering Tolerance

Cold Tolerance:GerminationVigor

Irrigation SchedulingGermplasm Development:

Photoperiod Sensitivity ConversionDevelopment of RIL populations for Cold ToleranceDevelopment of Novel Inbred Lines with Improved YieldsDevelopment of Annotated Gene Discovery Population

Improving Stand Establishment

Ethiopian Cold Tolerance

2,000 125 25

Cold GerminationField Germination & Vigor

COLD GERMINABILITY OF GERMPLASM

Cold Germination at 12 C for 72 h

April 10

April 11

April 30

2013

2015

Chinese Cold Tolerance RIL Populations

RTx430 x Gai Gaoliang (Released)BTx623 x Kaoliang (Ready for Release)BTx623 x Hong Ke Zi (Ready for Release)BTx623 x Niu Sheng Zui (1 Year Out)

Quantitative Trait Loci have been identified for cold germination and early season vigor.

Burow GB, Burke J., Franks CD, Xin, Z, 2011. Genetic dissection of early-season cold tolerance in sorghum (S. bicolor). Mol. Breeding, 28:391-402

Stand Establishment on Marginal Soils

We have recently identified a metabolic marker in sorghum that correlates with biomass accumulation on low nitrogen soils during the first three weeks following emergence.

Summary

• We have identified sorghum lines with excellent germination at low temperatures.

• We have identified sorghum lines with excellent vigor at low temperatures.

• We have mapped quantitative trait loci for cold tolerance during germination.

• We have identified a metabolic marker that correlates with improved seedling development in marginal soils having low nitrogen levels.

Improving Drought Tolerance

EARLY SEASON MOISTURE

Seasonal Rainfall Patterns

LATE SEASON MOISTURE

VARIABLE SEASON MOISTURE

EARLY SEASON MOISTURE

Seasonal Rainfall Patterns

LATE SEASON MOISTURE

VARIABLE SEASON MOISTURE

Post-Flowering Drought Tolerance

Pre-Flowering Drought Tolerance

Pre- and Post-Flowering Drought Tolerance

Symptoms of pre-flowering drought stress: leaf rolling, uncharacteristic leaf erectness, leaf bleaching, leaf tip and margin burn, delayed flowering, saddle effect, poor panicle exsertion, panicle blasting and floret abortion, and reduced panicle size.

Post-flowering water-deficit stress can have direct effects on grain size, as well as effects on harvest due to premature plant death, increased susceptibility to charcoal rot, and lodging, all of which effect yield potential.

Sorghum Responses to Drought

PRE - POST-

SCENECENT STAY-GREEN

SORGHUM DROUGHT TOLERANCE BIOASSAY DEVELOPED

Researchers at the Cropping Systems Research Laboratory developed an assay to identify “stay-green” sorghums without the requirement of post flowering water stress.

Dhurrin Determinations:Conversion Panel BTx623 * Niu Sheng Zui RILsAssociation Panel CSRL Breeding LinesBTx 642 * Tx7000 RILs AIMS LinesSC 56 * Tx7000 RILs Industry LinesEthiopian Collection Sudanese LinesKSU RILs

Leaf Dhurrin Content is a Quantitative Measure of the Level of Pre- and Post-flowering Drought Tolerance in Sorghum. Crop Sci. 53:1056–1065

Post-Flowering Tolerance

Pre-Flowering Tolerance

Pre- and Post-Flowering Tolerance

Dhurrin

Natural Variation in Synthesis and Catabolism Genes Influences Dhurrin Content in Sorghum(Sorghum bicolor L. Moench)

Genome-wide association analysis (GWAS) using a panel of 700 diverse converted sorghum lines.

Genes for biosynthesis and catabolism are important in determiningnatural variation for leaf dhurrin in sorghum in different environments.

BTx642/Tx7000 RIL QTL

Stay-green (1993-1998) and Dhurrin

Sudanese Stay-Green

367 8 3

Efficiency of Quantum YieldDhurrin levels

Ethiopian Stay-Green

2,000 125

Efficiency of Quantum YieldMaintenance of lower leaves under low lightDhurrin levels

22

Conversion of Photoperiod Sensitive Stay-Green Ethiopian Lines

Post-Flowering Tolerance

Pre-Flowering Tolerance

Pre- and Post-Flowering Tolerance

Dhurrin

Summary

• We have identified a relationship between leaf dhurrin levels and the level of post-flowering drought tolerance.

• We have identified the chromosomal regions associated with dhurrin accumulation and turnover.

• We have identified and released lines with pre-and post-flowering drought tolerance.

Sorghum Gene Discovery Population for Trait Improvement

We have developed technology to move from Quantitative Trait Loci (QTLs) to specific gene identification and subsequent development of perfect trait markers for molecular assisted breeding.

Sorghum Gene Discovery Population for Trait Improvement

F1

Pooled F2 plants homozygous for target trait

Background SNPs

Target Trait Gene

Other Genes

✕

BTx623 Plant with target trait

Sorghum Gene Discovery Population for Trait Improvement

Traits of Interest:

Yield

Protein Content

Protein Digestibility

Mineral Content (Iron, Zinc, etc.)

Sorghum Gene Discovery Population for Trait Improvement

MODERN SORGHUM HYBRIDS DO NOT SET SEED AT EVERY FLOWER!!!

Traits of Interest:

Yield

Traits of Interest:

Yield

Sorghum Gene Discovery Population for Trait Improvement

Screen Gene Discovery Population for Multi-seed Trait

Sorghum Gene Discovery Population for Trait Improvement

F1

Pooled F2 plants homozygous for msd trait

Background SNPs

Mutli-seedTrait Gene

Other Genes

✕

BTx623 Plant with msd trait

Sorghum Gene Discovery Population for Trait Improvement

Having identified the gene controlling the multiseed trait, we create msd gene specific markers for molecular breeding.

Screen segregating populations of inbredsused for hybrid production for the homozygous msd gene.

msd

Wild Type

Heterozygous

Sorghum Gene Discovery Population for Trait Improvement

Traits of Interest:

YieldWe can now move the multi-seed trait into any sorghum line.

Seed with this trait has been provided to seven sorghum seed companies.

Sorghum Gene Discovery Population for Trait Improvement

Traits of Interest:

Yield ✓

Protein Content

Protein Digestibility

Mineral Content (Iron, Zinc, etc.)

Sorghum Gene Discovery Population for Trait Improvement

Traits of Interest:

Protein Content

Screen Gene Discovery Population for Protein Content

Scott Bean, ARS, Manhattan, KS

Sorghum Gene Discovery Population for Trait Improvement

Traits of Interest:

Yield ✓

Protein Content ✓

Protein Digestibility

Mineral Content (Iron, Zinc, etc.)

Sorghum Gene Discovery Population for Trait Improvement

Traits of Interest:

Protein Digestibility

Screen Gene Discovery Population for Protein DigestibilityScott Bean, ARS, Manhattan, KS

Sorghum Gene Discovery Population for Trait Improvement

Traits of Interest:

Yield ✓

Protein Content ✓

Protein Digestibility ✓

Mineral Content (Iron, Zinc, etc.)

Sorghum Gene Discovery Population for Trait Improvement

Traits of Interest:Mineral Content (Iron, Zinc, etc.)

Mike Grusak 2014

02468

10121416

Zn

02468

1012141618

Fe

Sorghum Gene Discovery Population for Trait Improvement

Traits of Interest:

Yield ✓

Protein Content ✓

Protein Digestibility ✓

Mineral Content (Iron, Zinc, etc.) ✓

Summary

• The gene discovery library possesses many beneficial traits for sorghum improvement.

• An efficient pipeline has been established to identify genes underlying important traits.

• The sequenced population covers over 93% of the genes, enabling in sillico identification of the population for important genes.

Special thanks to the Sorghum Checkoff Program for their support of this research.