Sorghum ([Sorghum bicolor (L.) Moench]) is the fifth largest cereal crop globally used as food, feed, fodder, fuel, and fiber. Biofuels are gaining importance owing to increasing uncertainties in supply of fossil fuels and the environmental pollution associated with their use. Because of its high biomass production potential and wider adaptability, sorghum is among preferred crops for lingo-cellulosic or second generation (2G) biofuel production. A potential approach to improve sorghum as a biofuel feedstock is to reduce the cell wall lignin content leading to high cell wall digestibility and increasing cellulose and hemicellulose contents. Presently, production of 2G biofuels needs genotypes with good plant height, high biomass yield, high cellulose and hemicellulose and low lignin content.

1. IDENTIFICATION OF GENOMIC REGIONS ASSOCIATED WITH
BIOFUEL TRAITS IN SORGHUM MINICORE COLLECTION
ABSTRACT
Sorghum ([Sorghum bicolor (L.) Moench]) is the fifth largest cereal crop globally used as food, feed, fodder, fuel, and fiber. Biofuels are gaining importance owing to increasing uncertainties in supply of fossil fuels and the
environmental pollution associated with their use. Because of its high biomass production potential and wider adaptability, sorghum is among preferred crops for lingo-cellulosic or second generation (2G) biofuel production. A
potential approach to improve sorghum as a biofuel feedstock is to reduce the cell wall lignin content leading to high cell wall digestibility and increasing cellulose and hemicellulose contents. Presently, production of 2G biofuels
needs genotypes with good plant height, high biomass yield, high cellulose and hemicellulose and low lignin content. To investigate the variability of biofuel production potential in sorghum 242 minicore germplasm accessions
were assessed for agronomic traits and biomass composition followed by the identification of single nucleotide polymorphism (SNPs) for candidate biofuel traits. Genome Wide Association Study (GWAS) was done using an
association mapping panel of 242 minicore entries using approximately 290K million SNPs with a minor allele frequency of 0.01. Over two seasons 10 significantly loci were identified for plant height and 13 for dry biomass yield.
In biomass composition traits 15 loci were identified for cellulose, 10 for hemicellulose and 13 for lignin. Accessions with the desired traits for biofuel production can be used as donors in breeding program or as feedstocks for
biofuel production. The genomic analysis of sorghum minicore accessions has highlighted the regions/ candidate genes for targeted improvement in bioenergy sorghum.
INTRODUCTION
 Sorghum is increasingly becoming important for biofuel production owing to its high biomass production
potential, short-life cycle
 Lignin, cellulose and hemicellulose are the three main components of the plant cell wall and impact stalk
quality .
 GWAS is used to understand the genetic complexity of crop species of large number of diversity panels .
 Therefore the genomic regions responsible for biofuel traits were identified in sorghum minicore collection
using GWAS.
METHODOLOGY
 A total of 242 accessions of the sorghum minicore collection along with controls were evaluated in two post-
rainy seasons using alpha lattice design with two replications.
 The data was recorded for agronomic traits and composition analysis was done using Gerhardt Fibretherm.
 The phenotyping and genotyping data were analyzed in Farm CPU for Dry Biomass Yield (DBY), Cellulose (C),
Hemicellulose (HC), Lignin (LIG).
 CIRCOS was constructed for the identification and analysis of similarities and differences arising from
comparing different genomes.
CONCLUSION:
 This is the first report on SNP identification for high cellulose/hemicellulose and low lignin in sorghum
minicore collection.
 The SNPs identified in the present study can be used for crop improvement and for developing low lignin/high
cellulose genotypes.
 The identified lines with desired biofuel traits viz, low lignin, high dry biomass, cellulose, hemicellulose can be
used as parents in the breeding program.
 Association of candidate genes for low lignin and high cellulose/hemicellulose will help in improving
genotypes for fuel as well as fodder purpose.
 We found synteny among SNPs in the sorghum with other biofuel crop genomes such as Zea mays and Switch
grass for specific biomass related traits.
RESULTS
 High heritability was observed for candidate biofuel traits in individual and across seasons.
 Significant genotypic variance was observed for all the traits studied.
 Highly significant genotype × environment (G × E) (p<0.01) interaction was observed in all the traits across
seasons except for lignin (non-significant).
 23 SNPs were identified for DBY with 14 in post rainy (PR) 2013 season (Fig. 1a) and 9 in post rainy (PR) 2014
(Fig. 1b).
 For biochemical traits, total 31 SNPs were identified for cellulose, 12 in PR13 (Fig. 2a) 19 in PR14 (Fig. 2b). 10
SNPs for hemicellulose were identified in PR13 (Fig. 3a) and 15 SNPs in PR14 (Fig. 3b).
 Total 24 SNPs were identified for low lignin, 10 in PR13 (Fig. 4a) and 9 in PR14 (Fig. 4b).
 The SNPs for dry biomass yield in sorghum showed overlap with switchgrass and maize, whereas, cellulose
showed similarity with maize, switchgrass and Arabidopsis.
 Hemicellulose showed close similarity to all the three genomes while lignin was mostly associated with maize
and switchgrass.
h2- broad sense heritability; σ2g- genotypic variance; SE- standard error; PR-post-rainy; G×E- genotype × environment; ns- non-significant
@ p > 0.01
ACKNOWLEDGEMENTS:
 This work is part of PhD work from Department of Genetics, Osmania university
Hyderabad.
 Financial support from ICRISAT‘s Dryland Cereals research program.
 This work has been undertaken as part of the CGIAR Research Program -Dryland Cereals/
Genetic Gains.
Traits 2013 PR 2014 PR Across 2 seasons
Mean
(±SE)
h2
σ2g
(±SE)
Mean
(±SE) h2
σ2g
(±SE±)
Mean
(±SE)
h2
σ2g
(±SE)
σ2g ×E
DBY
(tha-1)
6.2
(±0.9)
94
18.1
(±0.9)
6.0
(±1.5)
82
13.1
(±2.3)
6.1
(±1.7)
80
24.7
(±1.6)
5.4
C (%)
34.3
(±2.8)
88
65.6
(±7.4)
31.1
(±5.9)
91
64.4
(±5.3)
32.7
(±3.0)
88
113.7
(±6.3)
13.6
HC(%)
29.4
(±2.0)
88
35.6
(±3.9)
26.4
(±3.0)
82
17.0
(±2.9)
27.9
(±2.3)
79
41.1
(±3.4)
9.5
LIG (%)
10.5
(±2.1)
89
40.2
(±4.4)
9.4
(±4.0)
89
31.8
(±3.2)
10.0
(±1.9)
95
66.3
(±3.8)
3.5ns
Table 1: ANOVA for candidate biofuel traits
Manhattan plots for candidate biofuel traits
Fig. 5 CIRCOS The SNPs for candidate biofuel traits between sorghum, Arabidopsis (At), maize
(Zm) and switchgrass (pv) established by intergenomic synteny
Dry biomass yield
Cellulose
Hemicellulose
Lignin
Rayaprolu Laavanya1,2, Sivasubramani S1, Rao Manohar D2, Deshpande S
P1**, Kumar Ashok A1 *
1International Crops Research Institute for the Semi-Arid Tropics (ICRISAT), Patancheru, 502324, India.
2 Department of Genetics, Osmania University, Hyderabad, India.
* Corresponding author email: a.ashokkumar@cgiar.org ** Co-corresponding author: s.deshpande@cigar.org