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1. SCHOOL OF PLANT SCIENCE
PLANT BREEDING PROGRAM
GRADUATE SEMINAR II (PLBR 571)
THE ROLE OF MOLECULAR BREEDING IN SORGHUM (Sorghum bicolor [L] MOENCH) DIVERSITY STUDY
BY: MASARAT ELIAS ID NO: PhD/0058/11
COURSE ADVISOR: PROFESSOR HABTAMU ZELEKE (PhD)
JULY , 2019
HARAMAYA UNIVERSITY

2. 1. Introduction
Objectives
2. Literature Review
3. Summary and Conclusion
4. References

3. 1. Introduction
• Sorghum (Sorghum bicolor (L.) Moench) is the fifth most important cereal
crop worldwide. It is a monocotyledon crop belonging to the family Gramnieae.
• It is naturally self-pollinated short day plant with the degree of spontaneous
cross pollination, in some cases, reaching up to 30% depending on panicle
types.

4. Introduction Cont’d
• Sorghum (Sorghum bicolor [L] Moench) has been cultivated since ancient times and is
currently a staple cereal in arid and semi-arid regions of the world.
• It has exceptional tolerance to drought, high temperature stresses and low soil fertility,
making it the crop of choice by millions of farmers in
(Ouedraogo et al., 2017).
• On the other hand, the biological basis of world food security relies on variability of genetic
resources(Ouedraogo et al., 2017).

5. Introduction Cont’d
• Genetic diversity analysis of Sorghum germplasm is fundamental for breeding
and conservation strategies of this important crop.
• Genetic diversity analysis can be carried out using phenotypic and genotypic base or
both.
• DNA-based molecular markers are more efficient to analyze a greater number of
genotypes (Mofokeng et al., 2014)

6. Introduction Cont’d
• Molecular markers detect the among germplasm
and allow more reliably and efficiently than
phenotypic markers.
• Molecular marker technology aids conventional breeding in various aspects,
Assess of genetic diversity and establish heterotic patterns,
Screen for useful genes,
Accelerate backcross breeding programs via selection of gene(s) of interest and
Identify and protect commercial cultivars through fingerprinting (Mofokeng et al., 2014).

7. Introduction Cont’d
• However, it has some due to natural sexual incompatibility barriers and
the narrow genetic variability in sorghum.
• Therefore, further enhancement of productivity, quality and resistance to biotic and abiotic stresses
(Iqbal et al., 2010).
• To date, various biotechniques, including tissue culture, genetic transformation, molecular markers,
genomics, proteomics and tilling, among others, have been successfully exploited in sorghum.
• The sorghum genome has recently been sequenced, providing a greater understanding of
genomics-assisted breeding in this crop(Iqbal et al., 2010).

8. Introduction Cont’d
Therefore, the general objective of this review paper is to comprehend on the
role of molecular breeding in Sorghum (Sorghum bicolor (L.) Moench] diversity
Study. Specific objectives includes:
To advance clue on sorghum diversity analysis with molecular tools.

9. 2. LITERATURE REVIEW
2.1 Historical Development of Sorghum Varieties
• It is believed that cultivated Sorghum [Sorghum bicolor (L.) Moench] was first
domesticated in north-eastern Africa.
• In 1951, Vavilov suggested
(Vavilov, 1951).
• Some researchers argue for multiple for the crop.
• The is, therefore, partly due to the diverse physical environments
occurring in the region and partly due to the interaction of man with the environment
(Rao et al., 2002).

10. Historical Development of Sorghum Variety Continued
• By 1960, 95% of U.S. sorghum was planted to and sorghum grain yields
doubled from the prehybrid era.
• Abilities to hrough the use of male-sterility coupled
with sufficient heterosis were key factors determining entry of the private sector into
sorghum breeding and hybrid seed production(Smith et al., 2010).
• DELKABA program and private companies like ( Frontier, Garst and Thomas, Pioneer)
actively involved in sorghum breeding program and hybrid seed development (Smith et
al., 2010).

11. 1.2 Diversity Studies on Sorghum Bicolor
• Molecular markers have been widely applied to characterize genetic diversity in
sorghum germplasm collections and in breeding programs(Nagara, 2017).
• Recent advancements in molecular markers and genome sequencing offer great
opportunity to investigate the genetic diversity in a very big germplasm.

12. 1.3 Uses of Molecular Markers
• Advancements in the techniques of molecular biology offer extended
information related to the genetic structure.
• Molecular markers provide an efficient way to effectively utilize
favorable genes.

13. 13

15. 2.3.1 Assaying Genetic Diversity Using Different Marker Systems
• The use of morphological traits to characterize germplasm at the species
level is easier, but the identification of genotypes within a species based
on morphological traits alone is relatively difficult (Patil, 2015).
• DNA markers could address these limitations effectively and have become the
markers of choice across plant species including sorghum (Patil, 2015)

16. 2.3.2 Molecular Diversity among Cultivated and Wild Sorghums
• With the advent of molecular markers, different DNA marker systems have been employed to
study the patterns of genetic diversity among sorghum accessions from the exsitu germplasm
collection.
RFLP(Deu et al., 2006).
RAPD (Arya et al., 2008), and
SSR (Ramu et al., 2013) have been deployed to study molecular diversity in sorghum.
• In many studies, different marker systems have been used in combination to study the diversity
(Geleta et al., 2006).
In the recent past, DArT markers have been developed and deployed in diversity and
population structure analysis in sorghum (Bouchet et al., 2012).
SNP resource is also now available for such analysis (Nelson et al., 2011).

17. 2.3.3 Potential Drawbacks of MAS
• MAS may be more expensive than
conventional techniques, especially for
the start up expenses and labor cost.
• Recomination between the marker and
gene of interest may leading to false
positives.

18. 18

19. 2.4 Genomic Selection
• GS is a form of MAS that simultaneously estimates all loci, haplotype, or markers
across the entire genome instead of just linked markers unlike MAS.
• There is no defined subset of significant markers used.
• GS considers genome wide markers to explain the total genetic and predict
breeding value of individuals
• GS depends on training of models and to optimize phenotypic predictions
• GS provides GEBV of individuals based on their genotypic data alone

20. Genomic Selection Continued

21. Genomic selection vs. Marker assisted selection
Marker assisted selection
• Relies on few linked markers (in
LD with the trait)
• Not effective for polygenic traits
• Required prior QTL mapping result
• Requires less bioinformatics
resources
Genomic selection
• Exploits all markers in LD with the
trait across the genome
• Potentially effective for polygenic traits
• Does not need QTL maps
• Requires extensive bioinformatic
resources and modeling exercises

22. 2.4 Investigation of Heterosis
• Molecular markers like SSRs have been used in the investigation of diversity
and heterosis in rice.
• Some studies have used transcriptome analysis to analyse the genes
involved in heterosis(Nadeem et al., 2018).

23. 2.6 Genetic and QTL Mapping
• Genetic mapping employs methods for identification of the locus of a
gene as well as for determination of the distance between two genes.
• Markers present close to the gene of interest on the same chromosome are
known as linked markers.
• QTL mapping is a method in which molecular markers are utilized to locate
the genes that affect the traits of interest.

24. 2.7 Genomic selection and Genome Editing Together
New Way in Crop Improvement
• The development of CRISPR (Clustered Regularly Interspaced Short
Palindromic Repeat), a gene-editing technology.
• This technique facilitates the direct improvement of less favourable alleles
into more favourable alleles (Wu et al.,2015).

25. 2.8 Applications of Diversity Analysis for Genetic Improvement in
Sorghum
• A genome-wide association study (GWAS) of a diverse panel of 300
accessions with 1,290 SNPs was conducted by Sukumaran et al., (2012),
• Identify of eight significant marker-trait associations after the
association analysis between 333 SNPs in candidate genes and/or loci
and grain quality traits.
• An SNP in starch synthase IIa (SSIIa) gene was associated with kernel
hardness (KH), while an SNP in starch synthase (SSIIb) gene and pSB1120
locus was associated with starch content(Patil, 2015)

26. 2.9 Future Scenario of Sorghum Improvement
•
• Molecular breeding strategies can help in developing cultivars with enhanced
productivity under moisture stress with stay-green traits and delayed senescence.
• With the availability of the whole- genome sequence, it should be possible to target
specific genes and employ genomic tools to adapt the sorghum for various future
needs(Patil, 2015).

27. 3. SUMMARY AND CONCLUSION
• Sorghum’s important role in shaping the future of modern agriculture cannot be denied. Thus,
it is expected that research on this crop would continue to expand in the years to come.
• One particular area that is already gaining momentum in sorghum research is the use of NGS
techniques that allow for the faster identification of causal genes through genotyping by
sequencing (GBS) and GWAS.
• These are welcome developments that are expected to speed-up sorghum research like never
before.

28. SUMMARY AND CONCLUSION Cont’d
• Unlocking the genotype barrier allows us to harness the natural diversity of
sorghum, hence, the different economically important traits that each genotype
has to offer.
• Aside from genotyping, phenotyping is also an important aspect of sorghum
molecular breeding.

29. 4. References
• Aruna C, Bhagwat VR, Madhusudhana R, Sharma V, Hussain T, Ghorade RB, Khandalkar HG,
Audilakshmi S, Seetharama N (2011) Identification and validation of genomic regions that affect shoot
fly resistance in sorghum [Sorghum bicolor (L.) Moench]. Theor Appl Genet 122:1617–1630
• Arya L, Verma M, Sandhia GS, Singh SK, Lakhanpaul S (2008) Pattern of genetic relationship as
revealed by AFLP markers in Indian sorghum [Sorghum bicolor (L.) Moench]. Indian J Genet 68:139–
144
• Billot C, Rivallan R, Sall MN, Fonceka D, Deu M, Glaszmann JC, Noyer JL, Rami JK, Risterucci AM,
Wincker P, Ramu P, Hash CT (2012) A reference microsatellite kit to assess for genetic diversity of
Sorghum bicolor (Poaceae). Am J Bot 99:e245–260
• Billot C, Ramu P, Bouchet S et al (2013) Massive sor- ghum collection genotyped with SSR markers to
enhance use of global genetic resources. PLoS One 8:e59714
• Bouchet S, Pot D, Deu M et al (2012) Genetic structure, linkage disequilibrium and signature of
selection in sorghum: lessons from physically anchored DArT markers. PLoS One 7:e33470
• Collard BC, Jahufer MZ, Brouwer JB, et al. An introduction to markers, quantitative trait loci (QTL)
mapping and marker-assisted selection for crop improvement: the basic concepts. Euphytica.
2005;142(1–2):169–196.

30. May God Bless You For Your Attention!
Thank You