Genome-Wide Association Study of Traits Involved in Biofuel Production in Sorghum

Sorghum is the world’s fifth major cereal and has huge biomass and high sugar content of stalk that are ideal for biofuel production. We performed genome-wide association study (GWAS) of traits involved in ethanol production using several hundreds of Sorghum accessions cultivated in the field at four different degrees of soil salinity. The experiment was performed in Los Mochis, Mexico, in 2013.

Stalk sugar contents increased under the higher severity of salinity stress, whilst culm length decreased considerably. Although culm length decreased, the increase of culm numbers may alleviate the decrease of fresh weight. Culm length showed the largest correlation among different soil conditions (0.82-0.92). Brix value (0.64-0.83) and fresh weight (0.70-0.85) showed the moderate correlation.

GWAS of culm length showed that the highest association on Chr09, which is related to dw1. The second highest association was detected on Chr05. Significant associations with brix were detected at different positions among four salinity conditions. SNPs on Chr03 and Chr02, however, were highly associated with brix when GWAS was performed on the average value of four conditions. Associations with fresh weight were relatively stable over the conditions except the most severe one, suggesting that under the most severe condition culm numbers may strongly influence to fresh weight.

We also performed GWAS in F₁ plants with common seed parents using the genotype data of their pollen parents. We detected SNPs associated with traits related to ethanol production, and found that the associated SNPs were quite different between F₁ and their inbred parent populations.