2.3 Transcriptional and translational analyses of sorghum biomass

The mysterious relationship between phenotype and genotype can be revealed by applying various biotechnological approaches such as proteomics, transcriptomics, and metabolomics [42]. In transcriptomics, a huge set of gene libraries can be established by employing different techniques of bioinformatics and next-generation sequencing [43]. Over the last decade, expression profiling experiments for genome-wide investigation in sorghum have been carried out to analyze responses to numerous abiotic and biotic stresses, to determine tissue-specific and genotype-specific gene expression motifs, and to disclose the genetic modification and expression divergence between different sorghum varieties.

RNA-seq technology for expression profiling has been applied in sorghum to study different gene functions [44]. This technique gives a precise assessment of gene expression at different stages of sorghum plant development [45].

Proteomics offers the set of the most efficient tools for recognition, assessment, and quantification of unique proteins. Our recent study [44] merged transcriptomic and proteomic approaches for screening sorghum germplasm best suited for bioenergy and for comparative analysis of protein expression of elite sorghum germplasm. The study was based on 24 USDA sorghum genotypes selected for biomass potential in the field experiments, which is already reported in this chapter [37]. For translational analysis, 12 out of 24 selected genotypes were divided into three groups based on stem height, since height is directly correlated with biomass in sorghum. Four short stature genotypes were chosen as negative control (Table 5).


#### Table 5.

PI-583832-02-SD and PI-329733-01-SD were also found genetically distinct from rest of the genotypes used in the study (Figure 4). Variance decomposition for optimal classification showed that there were 23.41 and 76.59% variances present

Cladogenesis studies using homology-based classification of 24 sorghum genotypes.

The sorghum germplasm with less lignin and protein contents is desirable for biofuel production. Sorghum genotype PI-609239-01-SD had maximum value of NDF (83.5%) and ash contents (19.5%), while genotype PI-303658-02-SD exhibited

Though sorghum is viewed as a cheap source of biofuel being able to grow on marginal lands, few studies have indicated the lower biofuel potential of energy sorghums grown on marginal lands than the crop land [41]. Hence, screening of energy sorghum having stress tolerance, with efficient production technology and conservation tillage practices, is the key element of sustainable commercial produc-

within and between classes, respectively.

tion of energy sorghum [5].

Figure 3.

Figure 4.

168

the maximum value (57.5%) of cellulose content.

Classification of 24 sorghum genotypes using UPGMA cluster analysis.

Biomass for Bioenergy - Recent Trends and Future Challenges

Sorghum genotypes and their respective groups based on height.

The in vitro-germinated, 15-day-old sorghum seedlings were used for protein extraction. Sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) revealed diverse banding pattern of proteins ranging in size from 14.9 to 124 kDa with different expression levels in all studied genotypes (Table 6).


#### Table 6.

SDS-PAGE-based banding pattern of various proteins in sorghum genotypes.

#### Figure 5.

genotypes in sorghum biomass improvement plans. Chromosomes six, seven, and nine carry QTLs for height in sorghum. This protein (Sobic.0 09G229800) is considered to be translated from Dw1, a gene greatly conserved in plants (Table 7). Earlier reports showed that Dw1 enhances the internodal length and weight of sorghum plant [49] and is in turn important for plant biomass production.

Profile of SORBI\_3009G229800 protein translated from Dw1 gene and upregulated in top sorghum genotypes.

Translation KXG22524.1

Blast result for confirming the SORB1\_3009G229800 protein against NCBI database.

Sorghum an Important Annual Feedstock for Bioenergy DOI: http://dx.doi.org/10.5772/intechopen.86086

Protein Uncharacterized protein Gene SORBI\_009G229800 Organism Sorghum bicolor Taxonomic identifier 4558 [NCBI] Proteomes UP000000768 Chromosome 9

Sequence databases CM000768 Genomic DNA

Last sequence update November 2, 2016

Energy sorghum is considered to be a promising biofuel feedstock to counteract

the depleted fossil fuel reserves. To keep pace with fast progressing sorghum genomics, recent phenomics tools have been evolved that are more efficient than traditional laborious field-based manual phenotyping methods. This chapter describes the results of recent studies involving 24 selected biomass sorghums. The

3. Conclusion

171

Figure 6.

Table 7.

Names and taxonomy

SDS-PAGE showed nine different bands in 12 selected sorghum genotypes. The banding pattern of four negative controls was different from the selected ones, which revealed low expression of proteins. The study showed a unique band of 56.1 kDa present only in all selected genotypes. This band represents a hypothetical protein Sobic.009G229800, which has 510 amino acids (Figures 5 and 6) and controls the internodal length of stem in sorghum, which is why short-stature sorghum genotypes were devoid of this protein.

Height is positively correlated with biomass production [46] and is reported to be independent of stem structural composition like cellulose, hemicellulose, and lignin contents [47]. The Quantitative trait loci (QTL) for total dry biomass has been found to be localized with height QTLs [48]. Hence, breeders aim for taller

#### Sorghum an Important Annual Feedstock for Bioenergy DOI: http://dx.doi.org/10.5772/intechopen.86086


#### Figure 6.

Blast result for confirming the SORB1\_3009G229800 protein against NCBI database.


#### Table 7.

SDS-PAGE showed nine different bands in 12 selected sorghum genotypes. The banding pattern of four negative controls was different from the selected ones, which revealed low expression of proteins. The study showed a unique band of 56.1 kDa present only in all selected genotypes. This band represents a hypothetical protein Sobic.009G229800, which has 510 amino acids (Figures 5 and 6) and controls the internodal length of stem in sorghum, which is why short-stature

Secondary structure prediction of SORB1\_3009G229800 protein responsible for stem internodal length.

Height is positively correlated with biomass production [46] and is reported to be independent of stem structural composition like cellulose, hemicellulose, and lignin contents [47]. The Quantitative trait loci (QTL) for total dry biomass has been found to be localized with height QTLs [48]. Hence, breeders aim for taller

sorghum genotypes were devoid of this protein.

Table 6.

Figure 5.

170

Genotype Protein weight (kDa)

Biomass for Bioenergy - Recent Trends and Future Challenges

SDS-PAGE-based banding pattern of various proteins in sorghum genotypes.

NSL-54978 124 97.6 64 56.1 40.5 38.7 32 14.9 PI-456441-03-SD 124 97.6 64 56.1 40.5 38.8 32 14.9 PI-525981-01-SD 124 97.6 71 64 56.1 40.5 38.8 32 14.9 PI-303656-01-SD 124 97.6 64 56.1 40.5 38.8 32 14.9

PI-457393-02-SD 71 64 56.1 40.5 38.8 32 PI-583832-02-SD 97.6 71 64 56.1 40.5 38.8 32 PI-620625-01-SD 71 64 56.1 40.5 38.8 32 PI-456415-03-SD 71 64 56.1 40.5 38.8 32 PI-648187-01-SD 97.6 71 64 56.1 40.5 38.8 32 PI-609239-01-SD 71 64 56.1 40.5 38.8 32 PI-330039-02-SD 97.6 64 56.1 40.5 38.8 32 PI-329733-01-SD 97.6 64 56.1 40.5 38.8 32 PI-643630-01-SD 97.6 64 40.5 32 PI-643735-03-SD 97.6 64 40.5 32 PI-643581-01-SD 64 40.5 32 PI-642993-01-SD 64 40.5 32

Profile of SORBI\_3009G229800 protein translated from Dw1 gene and upregulated in top sorghum genotypes.

genotypes in sorghum biomass improvement plans. Chromosomes six, seven, and nine carry QTLs for height in sorghum. This protein (Sobic.0 09G229800) is considered to be translated from Dw1, a gene greatly conserved in plants (Table 7). Earlier reports showed that Dw1 enhances the internodal length and weight of sorghum plant [49] and is in turn important for plant biomass production.
